Got 4Ah, not 5Ah, battery 18V (20V) - done right thing?

[Richard Smith]

Hi there

Ran SDS out of battery in one session at the mine - first time.

Is 18V - believe it's badged in the USA as 20V, but the physics of the
Li-ion cells surely says in reality it's the same batteries and
voltage (?).

Went by tool store - no 5Ah batteries I asked for.
Said well it's 12 UKPounds per Amp-hour, and we do have 4Ah
batteries.

Thinking - well take two identical 4Ah batteries, swap occasionally,
running-down charge in both?

4Ah battery is better in every other tool which takes that form of
battery - screwdrivers, twist-drill drills, etc.

But the draw of the "big" SDS drill - the biggest which takes the
"small" batteries - that power draw would go across more cells if a
5Ah battery. Would have been better?

What do you say?

Regards,
Rich Smith


PS - SDS drill drilling the sockets in granite to insert the
feathers&wedge to split granite boulders - simply a regular workhorse
now.
Also use for "misc" other tasks - drill holes into which hammer in wood
for screws holding light-fittings, etc, etc.

[Joe Gwinn]

Post by Richard Smith
Hi there
Ran SDS out of battery in one session at the mine - first time.
Is 18V - believe it's badged in the USA as 20V, but the physics of the
Li-ion cells surely says in reality it's the same batteries and
voltage (?).
Went by tool store - no 5Ah batteries I asked for.
Said well it's 12 UKPounds per Amp-hour, and we do have 4Ah
batteries.
Thinking - well take two identical 4Ah batteries, swap occasionally,
running-down charge in both?
4Ah battery is better in every other tool which takes that form of
battery - screwdrivers, twist-drill drills, etc.
But the draw of the "big" SDS drill - the biggest which takes the
"small" batteries - that power draw would go across more cells if a
5Ah battery. Would have been better?
What do you say?

Amp-hours measures total stored charge, but I think your question is
different, basically if the smaller battery will affect the ability to
drill hard granite.

If drilling isn't much affected, then the take two and swap approach
is perfectly serviceable.

My instinct is that drilling ability will be about the same, but will
make fewer drilled holes per charge. Unless these batteries are
awfully expensive, I'd just try it.

Joe Gwinn

Post by Richard Smith
PS - SDS drill drilling the sockets in granite to insert the
feathers&wedge to split granite boulders - simply a regular workhorse
now.
Also use for "misc" other tasks - drill holes into which hammer in wood
for screws holding light-fittings, etc, etc.

[Jim Wilkins]

"Richard Smith" wrote in message news:***@void.com...

Hi there

Ran SDS out of battery in one session at the mine - first time.

Is 18V - believe it's badged in the USA as 20V, but the physics of the
Li-ion cells surely says in reality it's the same batteries and
voltage (?).

Went by tool store - no 5Ah batteries I asked for.
Said well it's 12 UKPounds per Amp-hour, and we do have 4Ah
batteries.

Thinking - well take two identical 4Ah batteries, swap occasionally,
running-down charge in both?

4Ah battery is better in every other tool which takes that form of
battery - screwdrivers, twist-drill drills, etc.

But the draw of the "big" SDS drill - the biggest which takes the
"small" batteries - that power draw would go across more cells if a
5Ah battery. Would have been better?

What do you say?

Regards,
Rich Smith


PS - SDS drill drilling the sockets in granite to insert the
feathers&wedge to split granite boulders - simply a regular workhorse
now.
Also use for "misc" other tasks - drill holes into which hammer in wood
for screws holding light-fittings, etc, etc.

------------------------------

My understanding is that Lithiums can be formulated for various tradeoffs
between high discharge current and high Ah rating. Unless you find a spec
sheet for the cells with the discharge current rating and know how much the
drill draws you have to trust the manufacturer's competence and honesty.

In this spec sheet example the maximum discharge current is 6.5A, about
twice the Ah rating.
https://shop.baltrade.eu/339,Battery_18650_Li_ion_3400_mAh_Panasonic_NCR_18650B_Lithium_ion_cell
Notice that they give a typical and a minimum mAh capacity. Like steel,
batteries vary.

The C rating is the current the battery would provide for 1 hour before
falling to some minimum safe or useful voltage, though it's usually measured
at a lower current and longer time to get a more favorable higher number.

The Ah you can use in practice may be less than the rating because the
battery's internal resistance rises as it discharges and will lower the
output voltage under heavy load due to internal IR drop, so the battery
terminal voltage hits the minimum before it's fully discharged. The
indication is a higher battery voltage after removing the load, or with a
lighter load that causes less internal voltage drop, if you have one.

My job was once building the production line test stations that determine if
electrical products including op amps and computer memory meet their spec
sheet rating. Much of what I bought from Radio Shack and on Amazon didn't
quite pass my testing but was still usable, with care.

[Jim Wilkins]

"Richard Smith" wrote in message news:***@void.com...

Hi there

Ran SDS out of battery in one session at the mine - first time.

Is 18V - believe it's badged in the USA as 20V, but the physics of the
Li-ion cells surely says in reality it's the same batteries and
voltage (?).

-------------------------
Don't blame us.
https://toolguyd.com/dewalt-20v-max-vs-18v-2023/
"Bosch switched over from 10.8V to 12V Max starting in mid-2008..."

When I bought NiMH replacements for my 14.4V NiCad Dewalt drill I monitored
the charging current and voltage to see the difference. On a NiMH charger
the "14.4V" NiMH packs cut off the charge at 22V and quickly fall back to
18V, then slowly decrease. A pack I charged Tuesday measures 16.076V today.

[Clare Snyder]

Post by Richard Smith
Hi there
Ran SDS out of battery in one session at the mine - first time.
Is 18V - believe it's badged in the USA as 20V, but the physics of the
Li-ion cells surely says in reality it's the same batteries and
voltage (?).
Went by tool store - no 5Ah batteries I asked for.
Said well it's 12 UKPounds per Amp-hour, and we do have 4Ah
batteries.
Thinking - well take two identical 4Ah batteries, swap occasionally,
running-down charge in both?
4Ah battery is better in every other tool which takes that form of
battery - screwdrivers, twist-drill drills, etc.
But the draw of the "big" SDS drill - the biggest which takes the
"small" batteries - that power draw would go across more cells if a
5Ah battery. Would have been better?
What do you say?
Regards,
Rich Smith
PS - SDS drill drilling the sockets in granite to insert the
feathers&wedge to split granite boulders - simply a regular workhorse
now.
Also use for "misc" other tasks - drill holes into which hammer in wood
for screws holding light-fittings, etc, etc.

Are these lithium or NiMH? If lithium, which type? Some batteries can
safely be discharged at only 1C (4 amps for a 4Ah battery) while
others can be discharged at as much as 5C (20 amps), and others only
.5C (2 amps) without over-heating or deteriorating the battery.
Generally speaking the higher capacity battery is USUALLY better for
high discharge loads (heavy duty operation)

[Jim Wilkins]

"Clare Snyder" wrote in message news:***@4ax.com...

On Thu, 16 May 2024 15:43:01 +0100, Richard Smith <***@void.com>
wrote: ...

Are these lithium or NiMH? If lithium, which type? Some batteries can
safely be discharged at only 1C (4 amps for a 4Ah battery) while
others can be discharged at as much as 5C (20 amps), and others only
.5C (2 amps) without over-heating or deteriorating the battery.
Generally speaking the higher capacity battery is USUALLY better for
high discharge loads (heavy duty operation)

--------------------------------
Lithiums for RC models may be rated to deliver 50 ~ 100C discharge current.

This is a good overview of batteries:
https://rcplanes.online/guide3.htm

[Richard Smith]

Hi Clare, Jim, everyone.
These are DeWalt powertool batteries - 18V (20V?).
This characteristic you identify "1C" etc. becomes knowable?
Rich S

[Jim Wilkins]

"Richard Smith" wrote in message news:***@void.com...

Hi Clare, Jim, everyone.
These are DeWalt powertool batteries - 18V (20V?).
This characteristic you identify "1C" etc. becomes knowable?
Rich S

--------------------------
On 5/16/24 I wrote:
"The C rating is the current the battery would provide for 1 hour before
falling to some minimum safe or useful voltage, though it's usually measured
at a lower current and longer time to get a more favorable higher number."

https://batteryuniversity.com/article/bu-402-what-is-c-rate
"To obtain a reasonably good capacity reading, manufacturers commonly rate
alkaline and lead acid batteries at a very low 0.05C, or a 20-hour
discharge."

The only satisfactory way to determine a battery's C capacity is to
discharge it while recording the current and voltage, stopping when the
voltage falls to the specified end point, which may be either where the
battery may be damaged or the intended load will no longer function. Since
this is slow, tedious and requires special equipment there are ways to
estimate it, with varying accuracy. The professional way to measure it is
with a programmable electronic load. The one I used to test large electric
car batteries dumped its heat into a barrel of water.

At home I measure remaining battery capacity on the cheap with multimeters
that can send their readings to a computer and either the device that the
battery will operate or old surplus high power variable resistors as the
load. The rotary type (rheostat) can be adjusted while hot to keep the power
draw fairly constant as voltage decreases.

Using the device the battery will operate, typically refrigeration, tells me
if the battery can be trusted to operate it overnight, which is more useful
than the numerical Amp-hour capacity. An AC powered fridge draws a high
startup current which can trip an inverter's low input voltage sensor
although the battery could still provide the run current.

This and similar inexpensive devices can be wired into a stationary battery
system to act as a 'fuel gauge' that shows the amount of current drawn and
the voltage, from which you can determine when the battery has fully
discharged and program the Amp-hour value in as C so the meter will then
accurately(?) display the percentage of remaining charge. The fuel gauge
Amp-hour reading halts at the full programmed capacity and ignores
subsequent float charging current.

https://www.amazon.com/DROK-Multimeter-Charge-Discharge-Electricity-Overvoltage/dp/B01M5CWR2P/ref=cm_cr_arp_d_product_top?ie=UTF8

I set the Amp-hour capacity to the original rating and then can see the
actual remaining Amp-hours and percentage of battery deterioration when its
voltage falls near the full discharge level. The voltage rise when I switch
off the load indicates the internal resistance, which increases with age.
Separate calibrated meters connected directly to the battery terminals show
its voltage regardless of IR drops in the load circuit, which affect the
fuel gauge voltage reading.

[Jim Wilkins]

"Richard Smith" wrote in message news:***@void.com...

Hi Clare, Jim, everyone.
These are DeWalt powertool batteries - 18V (20V?).
This characteristic you identify "1C" etc. becomes knowable?
Rich S
--------------------------------

The problem with measuring C for battery tools is breaking the circuit to
measure the current. Voltage is accessible by hacking the charger but there
isn't room in the tool or battery for a shunt or Hall Effect sensor to
measure current, and the battery connectors are very difficult to copy for a
latching extension cord. I've had some luck reforming hobby store brass
tubing into rectangular sockets and AC line cord plugs into solid brass male
pins. I didn't try to fake the plastic housings, just made the electrical
connections tight enough for non-mobile testing. Fine stranded silicone
insulated wire is flexible enough to not dislodge the connectors.

Forming DIY electrical contacts is much easier with a lathe and milling
machine. Collets are preferable on the lathe, to avoid squishing tubing and
keep fingers away from chuck jaws. A small 6-jaw chuck is useful though not
essential. Mine is on a 5C mount and last served in an indexer to mill a
wrench hex on threaded rod, which a collet didn't grip securely enough.

[Clare Snyder]

Post by Richard Smith
Hi Clare, Jim, everyone.
These are DeWalt powertool batteries - 18V (20V?).
This characteristic you identify "1C" etc. becomes knowable?
Rich S

Are these MAX or XR batteries?

[Richard Smith]

Post by Clare Snyder

Post by Richard Smith
Hi Clare, Jim, everyone.
These are DeWalt powertool batteries - 18V (20V?).
This characteristic you identify "1C" etc. becomes knowable?
Rich S

Are these MAX or XR batteries?

"XR"
"XR 4Ah"

[Clare Snyder]

Post by Richard Smith
Hi Clare, Jim, everyone.
These are DeWalt powertool batteries - 18V (20V?).
This characteristic you identify "1C" etc. becomes knowable?
Rich S

If it is a MAX it is a 5S x 2P pack running LG HB4 1865 LiNiMnCoO2
cells rated at 1500Mah with a max current of 30 amps which is a 20C
rating!!!.

I strongly suspect the 5Ah pack uses higher capacity cells - which
ALMOST ALWAYS means lower max current rating - so you likely made the
right move.

[Jim Wilkins]

Post by Richard Smith
Hi Clare, Jim, everyone.
These are DeWalt powertool batteries - 18V (20V?).
This characteristic you identify "1C" etc. becomes knowable?
Rich S

If it is a MAX it is a 5S x 2P pack running LG HB4 1865 LiNiMnCoO2
cells rated at 1500Mah with a max current of 30 amps which is a 20C
rating!!!.

I strongly suspect the 5Ah pack uses higher capacity cells - which
ALMOST ALWAYS means lower max current rating - so you likely made the
right move.

-------------------------------
5S x 2P means two columns (Parallel) each stacked 5 cells high (Series),
thus the output is 5 times the individual cell voltage and the current is
twice it.

The SKU (Stock Keeping Unit) number matters.
https://www.awholenother.com/2022/12/14/dewalt-20v-batteries.html

[Richard Smith]

Post by Clare Snyder

Post by Richard Smith
Hi Clare, Jim, everyone.
These are DeWalt powertool batteries - 18V (20V?).
This characteristic you identify "1C" etc. becomes knowable?
Rich S

If it is a MAX it is a 5S x 2P pack running LG HB4 1865 LiNiMnCoO2
cells rated at 1500Mah with a max current of 30 amps which is a 20C
rating!!!.
I strongly suspect the 5Ah pack uses higher capacity cells - which
ALMOST ALWAYS means lower max current rating - so you likely made the
right move.

The 5Ah battery is physically bigger. So likely has the same "duty
severity" as an other Ah size in the range?
Anyway, I will take that bit that I might have made the better choice
getting the 4Ah battery :-)

So yes, as replied previously, these are DeWAlt XR 18V 4Ah batteries
https://www.dewalt.co.uk/product/dcb182-xj/18v-xr-4ah-battery


Just as a bit of perspective - having been using these batteries in the
DeWalt DCH263
https://www.dewalt.co.uk/product/dch263n-xj/18v-xr-brushless-28mm-sds-plus-hammer-drill-bare-unit
for drilling about 70mm deep sockets 12mm (or 14mm) dia into hard
granite
(airleg / jackleg rock-drills need to use a simple single-cutter
drill-bit (like a big masonry drill) - not star-drill or button-bits -
I've seen that being likewise on a modern drill at a commercial mine in
the area)
doing a competent job - what that means relatively came to me when I
was drilling a brick wall for a friend to put up shelves - I could
barely restrict the power of the drill low enough to not "shoot"
straight through the wall before you could stop it.
So those 4Ah batteries doing a fair number of sockets in granite for
feathers-and-wedge is "not insignificant".

One intention being worked here in Cornwall is quarrying for lithium
minerals... Some of the granites have lithium-mica. To make
batteries...

[Bob La Londe]

I found in a lot of cordless tools the higher amp hour rated battery the
better. Generally I have not noted it for light load tools like a
cordless drill using small bits, but things like electric chainsaw,
angle grinder, etc it was very noticeable. I do not mean just that the
bigger AH rating ran longer. I mean it delivered more current in a
short fixed time period. The tool performed better. I've experienced
this with relatively cheap lines like Harbor Freights Bauer line and
with better pro and pro-sumer cordless tools like Milwaukee and DeWalt.
If you follow the YouTube channel "The Torque Test Channel" they mirror
this result with more subjective data across a range of tools including
drills and impact wrenches.

[Jim Wilkins]

"Bob La Londe" wrote in message news:v28e5m$2btdu$***@dont-email.me...

I found in a lot of cordless tools the higher amp hour rated battery the
better. Generally I have not noted it for light load tools like a
cordless drill using small bits, but things like electric chainsaw,
angle grinder, etc it was very noticeable. I do not mean just that the
bigger AH rating ran longer. I mean it delivered more current in a
short fixed time period. The tool performed better. I've experienced
this with relatively cheap lines like Harbor Freights Bauer line and
with better pro and pro-sumer cordless tools like Milwaukee and DeWalt.
If you follow the YouTube channel "The Torque Test Channel" they mirror
this result with more subjective data across a range of tools including
drills and impact wrenches.

----------------------------

Interesting. My high powered tools are corded and I don't have recent
experience with new battery tools, or much else that's new, I just prepped a
37 year old garden tractor for summer. Maybe the higher Ah packs are newer
tech that performs better. Lithium batteries are still evolving.
https://www.joules-solar.com/articles/lto-vs-lifepo4-chemistry

[Bob La Londe]

Post by Bob La Londe
I found in a lot of cordless tools the higher amp hour rated battery the
better.  Generally I have not noted it for light load tools like a
cordless drill using small bits, but things like electric chainsaw,
angle grinder, etc it was very noticeable.  I do not mean just that the
bigger AH rating ran longer.  I mean it delivered more current in a
short fixed time period.  The tool performed better.  I've experienced
this with relatively cheap lines like Harbor Freights Bauer line and
with better pro and pro-sumer cordless tools like Milwaukee and DeWalt.
If you follow the YouTube channel "The Torque Test Channel" they mirror
this result with more subjective data across a range of tools including
drills and impact wrenches.
----------------------------
Interesting. My high powered tools are corded and I don't have recent
experience with new battery tools, or much else that's new, I just
prepped a 37 year old garden tractor for summer. Maybe the higher Ah
packs are newer tech that performs better. Lithium batteries are still
evolving.
https://www.joules-solar.com/articles/lto-vs-lifepo4-chemistry

I think its more likely adjustment of the internal BMS depending on how
the larger battery is configured to make it larger. For instance if it
has an extra bank of cells it can 100% certainly deliver more current.
Just like tying two car batteries in parallel gives you more current
capacity. I expect larger cells might also be capable of more current
if the conductors are sized accordingly.

[Bob La Londe]

Post by Bob La Londe

Post by Bob La Londe
I found in a lot of cordless tools the higher amp hour rated battery the
better.  Generally I have not noted it for light load tools like a
cordless drill using small bits, but things like electric chainsaw,
angle grinder, etc it was very noticeable.  I do not mean just that the
bigger AH rating ran longer.  I mean it delivered more current in a
short fixed time period.  The tool performed better.  I've experienced
this with relatively cheap lines like Harbor Freights Bauer line and
with better pro and pro-sumer cordless tools like Milwaukee and DeWalt.
If you follow the YouTube channel "The Torque Test Channel" they mirror
this result with more subjective data across a range of tools including
drills and impact wrenches.
----------------------------
Interesting. My high powered tools are corded and I don't have recent
experience with new battery tools, or much else that's new, I just
prepped a 37 year old garden tractor for summer. Maybe the higher Ah
packs are newer tech that performs better. Lithium batteries are still
evolving.
https://www.joules-solar.com/articles/lto-vs-lifepo4-chemistry

I think its more likely adjustment of the internal BMS depending on how
the larger battery is configured to make it larger.  For instance if it
has an extra bank of cells it can 100% certainly deliver more current.
Just like tying two car batteries in parallel gives you more current
capacity.  I expect larger cells might also be capable of more current
if the conductors are sized accordingly.

I should note that there have been reports of some tools being smoked by
running harder with the uber battery packs like the DeWalt 20/60 that
delivers 20V and lots of capacity or 60V and less capacity depending on
what tool its plugged in to.

[Jim Wilkins]

...

I think its more likely adjustment of the internal BMS depending on how
the larger battery is configured to make it larger. For instance if it
has an extra bank of cells it can 100% certainly deliver more current.
Just like tying two car batteries in parallel gives you more current
capacity. I expect larger cells might also be capable of more current
if the conductors are sized accordingly.
Bob La Londe
CNC Molds N Stuff

-------------------------------------
Beyond the BMS limits, the capacity and internal resistance depend on
details of the chemical formulation and physical structure, such as particle
size, which may be trade secrets. I've read that they can be traded off
depending on the intended load current, higher resistance for greater
capacity and vice versa.
https://www.linkedin.com/pulse/what-does-c-mean-lithium-ion-batteries-bruce-feng

Marine batteries are similar, the high capacity deep cycle ones for trolling
motors aren't recommended for engine starting current.

[Richard Smith]

Hi all
Thanks for comment.
At the time I needed it there were only 4Ah batteries in stock, and I
got what I got.

I must be doing something right, because I got into the
meet/introduce/interview event of a local mine which is re-opening.

For light tools 4Ah is fine and I now have two.
If I do lot-lot-lot of bigger drilling, might stock-up on higher Ah
batteries. Come that time there could be some "new" battery I am glad
it is my option to get.

Comment / reminder - I got the biggest drill using "small tool" batteries.

[Bob La Londe]

Post by Richard Smith
Hi all
Thanks for comment.
At the time I needed it there were only 4Ah batteries in stock, and I
got what I got.
I must be doing something right, because I got into the
meet/introduce/interview event of a local mine which is re-opening.
For light tools 4Ah is fine and I now have two.
If I do lot-lot-lot of bigger drilling, might stock-up on higher Ah
batteries. Come that time there could be some "new" battery I am glad
it is my option to get.
Comment / reminder - I got the biggest drill using "small tool" batteries.

To be fair... My experience is that you still get useful power out of
the "moderately" large batteries like your 4AH as opposed to 5AH. It
just may not be "as powerful." Where you see huge differences in base
power even over a very very short time is the smaller batteries. Often
the "cheap" batteries packaged with an all in one kit.
Tool/battery/charger... They don't give you full power for a short
time. They just don't give you full power at all.

[Jim Wilkins]

Post by Richard Smith
Hi all
Thanks for comment.
At the time I needed it there were only 4Ah batteries in stock, and I
got what I got.
I must be doing something right, because I got into the
meet/introduce/interview event of a local mine which is re-opening.
For light tools 4Ah is fine and I now have two.
If I do lot-lot-lot of bigger drilling, might stock-up on higher Ah
batteries. Come that time there could be some "new" battery I am glad
it is my option to get.
Comment / reminder - I got the biggest drill using "small tool" batteries.

To be fair... My experience is that you still get useful power out of
the "moderately" large batteries like your 4AH as opposed to 5AH. It
just may not be "as powerful." Where you see huge differences in base
power even over a very very short time is the smaller batteries. Often
the "cheap" batteries packaged with an all in one kit.
Tool/battery/charger... They don't give you full power for a short
time. They just don't give you full power at all.
Bob La Londe
CNC Molds N Stuff

----------------------------
If you could access the electrical circuit a PZEM-051 meter would give you
all the useful data. For under $20 they measure DC up to 100V and 100A,
calculate the power and the total energy in Watt-hours.

[Bob La Londe]

Post by Bob La Londe

Post by Richard Smith
Hi all
Thanks for comment.
At the time I needed it there were only 4Ah batteries in stock, and I
got what I got.
I must be doing something right, because I got into the
meet/introduce/interview event of a local mine which is re-opening.
For light tools 4Ah is fine and I now have two.
If I do lot-lot-lot of bigger drilling, might stock-up on higher Ah
batteries.  Come that time there could be some "new" battery I am glad
it is my option to get.
Comment / reminder - I got the biggest drill using "small tool" batteries.

To be fair... My experience is that you still get useful power out of
the "moderately" large batteries like your 4AH as opposed to 5AH.  It
just may not be "as powerful."  Where you see huge differences in base
power even over a very very short time is the smaller batteries.  Often
the "cheap" batteries packaged with an all in one kit.
Tool/battery/charger...  They don't give you full power for a short
time.  They just don't give you full power at all.
Bob La Londe
CNC Molds N Stuff
----------------------------
If you could access the electrical circuit a PZEM-051 meter would give
you all the useful data. For under $20 they measure DC up to 100V and
100A, calculate the power and the total energy in Watt-hours.

Torque Test Channel does some decent testing using a load. I don't need
to be an expert on the details. I just need to know the results, and
remember my anecdotal, but not irrelevant, direct experience.

[Bob La Londe]

Post by Bob La Londe

...

I think its more likely adjustment of the internal BMS depending on how
the larger battery is configured to make it larger.  For instance if it
has an extra bank of cells it can 100% certainly deliver more current.
Just like tying two car batteries in parallel gives you more current
capacity.  I expect larger cells might also be capable of more current
if the conductors are sized accordingly.
Bob La Londe
CNC Molds N Stuff
-------------------------------------
Beyond the BMS limits, the capacity and internal resistance depend on
details of the chemical formulation and physical structure, such as
particle size, which may be trade secrets. I've read that they can be
traded off depending on the intended load current, higher resistance for
greater capacity and vice versa.
https://www.linkedin.com/pulse/what-does-c-mean-lithium-ion-batteries-bruce-feng
Marine batteries are similar, the high capacity deep cycle ones for
trolling motors aren't recommended for engine starting current.

I think you are over thinking it. Sure changes in technology can make a
difference, but often larger battery packs are just larger. Quite often
when you dig into various mid to good quality battery packs you find
they have the same cells from the same manufacturer. Assembly quality
is an issue, as is the choice and programming of the BMS, but the cells
are the same.

I have a bit more experience with marine deep cycle lead acid batteries,
and I don't think its as big of a deal as you think. I've even run
combined usage with the base ground battery doing double duty as the
cranking battery and the ground battery for the trolling motor. I've
done it for years, and other anglers I know have done it for years
before me. Its a way to run a larger trolling motor when battery space
is limited. I did run four batteries in my current 20'10" bass boat
because I have the room for them. In my newest smaller acquisition
there is no space for 4 batteries, but I noticed it has a 36V trolling
motor on the bow. They have just been running it on 24V. Runs fine.
Just less power. I'll be converting it to the dual usage cranking
battery configuration as soon as I have enough play money to buy all new
matching batteries for that one. Could they get better life if
configured differently. Maybe. That all is a bit of a tangent though.

[Jim Wilkins]

Post by Bob La Londe
...
I have a bit more experience with marine deep cycle lead acid batteries,
and I don't think its as big of a deal as you think. ...
Bob La Londe

I post what I've seen at reliable sources, it's as cautious as the battery
manufacturers choose to be.

Personally I test batteries by loading them down with a carbon pile until
they scream for mercy, and rarely mention the results because they vary so
widely. I tested stuff to and beyond its limits professionally and have
acquired or built the gear to find those limits at home. I don't blow up
batteries any more but I have tested circuit breakers to destruction.

UL "safety" testing is -dangerous-, much smoke and flame. The old theatre
curtain recipe of dipping cotton cloth in a solution of alum and borax
really does let it pass the vertical burning test.
https://elteklabs.com/test-capabilities/material-tests/flame-fire-hazard/

[Bob La Londe]

Post by Jim Wilkins

Post by Bob La Londe
...
I have a bit more experience with marine deep cycle lead acid
batteries, and I don't think its as big of a deal as you think. ...
Bob La Londe

I post what I've seen at reliable sources, it's as cautious as the
battery manufacturers choose to be.
Personally I test batteries by loading them down with a carbon pile
until they scream for mercy, and rarely mention the results because they
vary so widely. I tested stuff to and beyond its limits professionally
and have acquired or built the gear to find those limits at home. I
don't blow up batteries any more but I have tested circuit breakers to
destruction.
UL "safety" testing is -dangerous-, much smoke and flame. The old
theatre curtain recipe of dipping cotton cloth in a solution of alum and
borax really does let it pass the vertical burning test.
https://elteklabs.com/test-capabilities/material-tests/flame-fire-hazard/

I never was employed doing destructive testing, but I did spend a decade
or two doing low voltage communication contracting. I learned there is
what they say, and there is what there is. Usually what they say fell
short in my field, but sometimes it didn't.

When they say an IR motion sensor will detect motion at 90 feet they
mean if ambient is below 70F and the subject is large and is running a
fever. LOL. They don't say if ambient is 90+ its virtually worthless.

Seriously there are thousands of bass boats that don't have room for 4
big deep cycles batteries running just three in series for the 36V TM
and tapping the positive of the ground battery for nominal 12V for
cranking and accessories. The big thing is to charge as soon as they
cool down (or get back to the hotel), and to have three equal batteries.

With most pros running 20-23 foot glitter barges these days most have
plenty of room in the back for batteries, but some older boats and/or
smaller boats didn't. Many have also switched over to a single high
voltage lithium for their TM battery for motors upto 48V. I wonder how
they do on the Potomac in a winter tournament before sunrise when the
water gels on the line and freezes in the reel. The lead acid deep
cycles would work. Something has to keep the lithiums from dropping to
ambient temperature.

Anyway, this is all tangent of tangent now.

[Clare Snyder]

Post by Bob La Londe

Post by Jim Wilkins

Post by Bob La Londe
...
I have a bit more experience with marine deep cycle lead acid
batteries, and I don't think its as big of a deal as you think. ...
Bob La Londe

I post what I've seen at reliable sources, it's as cautious as the
battery manufacturers choose to be.
Personally I test batteries by loading them down with a carbon pile
until they scream for mercy, and rarely mention the results because they
vary so widely. I tested stuff to and beyond its limits professionally
and have acquired or built the gear to find those limits at home. I
don't blow up batteries any more but I have tested circuit breakers to
destruction.
UL "safety" testing is -dangerous-, much smoke and flame. The old
theatre curtain recipe of dipping cotton cloth in a solution of alum and
borax really does let it pass the vertical burning test.
https://elteklabs.com/test-capabilities/material-tests/flame-fire-hazard/

I never was employed doing destructive testing, but I did spend a decade
or two doing low voltage communication contracting. I learned there is
what they say, and there is what there is. Usually what they say fell
short in my field, but sometimes it didn't.
When they say an IR motion sensor will detect motion at 90 feet they
mean if ambient is below 70F and the subject is large and is running a
fever. LOL. They don't say if ambient is 90+ its virtually worthless.
Seriously there are thousands of bass boats that don't have room for 4
big deep cycles batteries running just three in series for the 36V TM
and tapping the positive of the ground battery for nominal 12V for
cranking and accessories. The big thing is to charge as soon as they
cool down (or get back to the hotel), and to have three equal batteries.
With most pros running 20-23 foot glitter barges these days most have
plenty of room in the back for batteries, but some older boats and/or
smaller boats didn't. Many have also switched over to a single high
voltage lithium for their TM battery for motors upto 48V. I wonder how
they do on the Potomac in a winter tournament before sunrise when the
water gels on the line and freezes in the reel. The lead acid deep
cycles would work. Something has to keep the lithiums from dropping to
ambient temperature.
Anyway, this is all tangent of tangent now.
--
Bob La Londe
CNC Molds N Stuff

Just keep the trolling motor running under load and the batteries
will stay warm. Don't stop for a beer!!!

[Jim Wilkins]

"Bob La Londe" wrote in message news:v2djrv$3hfus$***@dont-email.me...

Something has to keep the lithiums from dropping to
ambient temperature.
Bob La Londe

-------------------------------
Insulated cooler? Don't forget and add ice.

Some LiFePO4s use charging current to warm themselves above freezing before
applying it to the cells.

[Jim Wilkins]

"Bob La Londe" wrote in message news:v2djrv$3hfus$***@dont-email.me...

On 5/18/2024 7:33 PM, Jim Wilkins wrote:
...

I never was employed doing destructive testing, but I did spend a decade
or two doing low voltage communication contracting. I learned there is
what they say, and there is what there is. Usually what they say fell
short in my field, but sometimes it didn't.

When they say an IR motion sensor will detect motion at 90 feet they
mean if ambient is below 70F and the subject is large and is running a
fever. LOL. They don't say if ambient is 90+ its virtually worthless.

---------------------
Most of the testing was to find and reject or reclassify parts that didn't
meet specifications for companies that cared, or burn-in testing to weed out
early failures by operating at elevated temperature for a week. The exact
conditions were usually secret, I had to provide a range of adjustment.
Sometimes there had to be provision for destructive failure, such as
Chrysler Lean Burn engine controllers with components not rated for possible
under-hood temperatures.

Before Congress mandated emissions and fuel economy standards that needed
electronic control to meet, the only electronic device in a car was the
radio which the auto makers bought, they had to hire new engineers
unfamiliar with the heat, water, dirt, salt and vibration, who took time to
learn. I had the partial advantages of military electronic experience which
solves those, in commercially unaffordable ways, plus a hands-on
apprenticeship in custom electro-mechanical machine design. The engine
compartment environment can be nearly as challenging as military aircraft
specs, consider a snow plow driver in Alaska starting cold and diving full
throttle into the deep snow in front of the truck, or splashing through an
icy puddle.

Heat in the South is another issue that's not so evident in Michigan. I know
what Atlanta is like in summer.

[Bob La Londe]

Post by Bob La Londe
...
I never was employed doing destructive testing, but I did spend a decade
or two doing low voltage communication contracting.  I learned there is
what they say, and there is what there is.  Usually what they say fell
short in my field, but sometimes it didn't.
When they say an IR motion sensor will detect motion at 90 feet they
mean if ambient is below 70F and the subject is large and is running a
fever.  LOL.  They don't say if ambient is 90+ its virtually worthless.
---------------------
Most of the testing was to find and reject or reclassify parts that
didn't meet specifications for companies that cared, or burn-in testing
to weed out early failures by operating at elevated temperature for a
week. The exact conditions were usually secret, I had to provide a range
of adjustment. Sometimes there had to be provision for destructive
failure, such as Chrysler Lean Burn engine controllers with components
not rated for possible under-hood temperatures.
Before Congress mandated emissions and fuel economy standards that
needed electronic control to meet, the only electronic device in a car
was the radio which the auto makers bought, they had to hire new
engineers unfamiliar with the heat, water, dirt, salt and vibration, who
took time to learn. I had the partial advantages of military electronic
experience which solves those, in commercially unaffordable ways, plus a
hands-on apprenticeship in custom electro-mechanical machine design. The
engine compartment environment can be nearly as challenging as military
aircraft specs, consider a snow plow driver in Alaska starting cold and
diving full throttle into the deep snow in front of the truck, or
splashing through an icy puddle.
Heat in the South is another issue that's not so evident in Michigan. I
know what Atlanta is like in summer.

Bell Labs had material test sites down here in the Sonoran Desert for
environmental testing. Death Valley may be the only place in North
America more hostile than the low Sonoran Desert. They had panels setup
with material samples affixed out along the southern rail line right of
way. Maybe they still do (if they are still some form of Bell Labs). I
haven't checked in a long time.

[Bob La Londe]

Post by Bob La Londe

Post by Bob La Londe
...
I never was employed doing destructive testing, but I did spend a decade
or two doing low voltage communication contracting.  I learned there is
what they say, and there is what there is.  Usually what they say fell
short in my field, but sometimes it didn't.
When they say an IR motion sensor will detect motion at 90 feet they
mean if ambient is below 70F and the subject is large and is running a
fever.  LOL.  They don't say if ambient is 90+ its virtually worthless.
---------------------
Most of the testing was to find and reject or reclassify parts that
didn't meet specifications for companies that cared, or burn-in
testing to weed out early failures by operating at elevated
temperature for a week. The exact conditions were usually secret, I
had to provide a range of adjustment. Sometimes there had to be
provision for destructive failure, such as Chrysler Lean Burn engine
controllers with components not rated for possible under-hood
temperatures.
Before Congress mandated emissions and fuel economy standards that
needed electronic control to meet, the only electronic device in a car
was the radio which the auto makers bought, they had to hire new
engineers unfamiliar with the heat, water, dirt, salt and vibration,
who took time to learn. I had the partial advantages of military
electronic experience which solves those, in commercially unaffordable
ways, plus a hands-on apprenticeship in custom electro-mechanical
machine design. The engine compartment environment can be nearly as
challenging as military aircraft specs, consider a snow plow driver in
Alaska starting cold and diving full throttle into the deep snow in
front of the truck, or splashing through an icy puddle.
Heat in the South is another issue that's not so evident in Michigan.
I know what Atlanta is like in summer.

Bell Labs had material test sites down here in the Sonoran Desert for
environmental testing.  Death Valley may be the only place in North
America more hostile than the low Sonoran Desert.  They had panels setup
with material samples affixed out along the southern rail line right of
way.  Maybe they still do (if they are still some form of Bell Labs).  I
haven't checked in a long time.

I'm not a fan of Michigan weather. My wife used to go to the Wheatland
Music festival every year and of course she convinced me to go one time.
Middle of summer. Should have been fine. It rained everyday (most of
the day) and we camped out. I was cold and wet the entire time, and of
course I felt like I came down with a cold the second day... and she
volunteered us to work the info booth one shift every day. Can't say
how many times I said, "Ice truck is that," "Bathrooms are that way."

When I was a kid I wanted to live where there was snow and trees.
Now... No. I am good right here. Yeah the heat is miserable, but its
familiar, and my office is air conditioned. Actually, so is my main CNC
machine room now. The rest of the shop... well an ice tea tastes so
much better when I get out of the main shop and back into the office.

[Clare Snyder]

Post by Bob La Londe

Post by Bob La Londe

Post by Bob La Londe
...
I never was employed doing destructive testing, but I did spend a decade
or two doing low voltage communication contracting.  I learned there is
what they say, and there is what there is.  Usually what they say fell
short in my field, but sometimes it didn't.
When they say an IR motion sensor will detect motion at 90 feet they
mean if ambient is below 70F and the subject is large and is running a
fever.  LOL.  They don't say if ambient is 90+ its virtually worthless.
---------------------
Most of the testing was to find and reject or reclassify parts that
didn't meet specifications for companies that cared, or burn-in
testing to weed out early failures by operating at elevated
temperature for a week. The exact conditions were usually secret, I
had to provide a range of adjustment. Sometimes there had to be
provision for destructive failure, such as Chrysler Lean Burn engine
controllers with components not rated for possible under-hood
temperatures.
Before Congress mandated emissions and fuel economy standards that
needed electronic control to meet, the only electronic device in a car
was the radio which the auto makers bought, they had to hire new
engineers unfamiliar with the heat, water, dirt, salt and vibration,
who took time to learn. I had the partial advantages of military
electronic experience which solves those, in commercially unaffordable
ways, plus a hands-on apprenticeship in custom electro-mechanical
machine design. The engine compartment environment can be nearly as
challenging as military aircraft specs, consider a snow plow driver in
Alaska starting cold and diving full throttle into the deep snow in
front of the truck, or splashing through an icy puddle.
Heat in the South is another issue that's not so evident in Michigan.
I know what Atlanta is like in summer.

Bell Labs had material test sites down here in the Sonoran Desert for
environmental testing.  Death Valley may be the only place in North
America more hostile than the low Sonoran Desert.  They had panels setup
with material samples affixed out along the southern rail line right of
way.  Maybe they still do (if they are still some form of Bell Labs).  I
haven't checked in a long time.

I'm not a fan of Michigan weather. My wife used to go to the Wheatland
Music festival every year and of course she convinced me to go one time.
Middle of summer. Should have been fine. It rained everyday (most of
the day) and we camped out. I was cold and wet the entire time, and of
course I felt like I came down with a cold the second day... and she
volunteered us to work the info booth one shift every day. Can't say
how many times I said, "Ice truck is that," "Bathrooms are that way."
When I was a kid I wanted to live where there was snow and trees.
Now... No. I am good right here. Yeah the heat is miserable, but its
familiar, and my office is air conditioned. Actually, so is my main CNC
machine room now. The rest of the shop... well an ice tea tastes so
much better when I get out of the main shop and back into the office.
--
Bob La Londe
CNC Molds N Stuff

You can put on extra clothes until you are warm - you can't take off
enough to be cool - - - Personally There is no place like the area
dead between the lakes in South Western Ontario. In the summer it can
be uncomfortably warm and humid for a few weeks- sometimes not even
cooling off over night - so air conditioning (in home and car) is
pretty well mandatory - and we get numerous thunder storms - but we
are just south east of Ontario's "tornado alley"so seldom get SERIOUS
storms - and the winter is moderated by the lakes as well - very
seldom get long periods of VERY cold weather - and in the little
stretch of heaven called Waterloo Region we've been in something of a
"snow shadow" for the last several decades, getting less snow than
areas to the North, west, and even south ( as little as 15 miles away
can have significantly more snow).

[Jim Wilkins]

"Clare Snyder" wrote in message news:***@4ax.com...

You can put on extra clothes until you are warm - you can't take off
enough to be cool - - - Personally There is no place like the area
dead between the lakes in South Western Ontario. In the summer it can
be uncomfortably warm and humid for a few weeks- sometimes not even
cooling off over night - so air conditioning (in home and car) is
pretty well mandatory - and we get numerous thunder storms - but we
are just south east of Ontario's "tornado alley"so seldom get SERIOUS
storms - and the winter is moderated by the lakes as well - very
seldom get long periods of VERY cold weather - and in the little
stretch of heaven called Waterloo Region we've been in something of a
"snow shadow" for the last several decades, getting less snow than
areas to the North, west, and even south ( as little as 15 miles away
can have significantly more snow).
-----------------------------

New England to your east is generally similar though the meandering Jet
Stream can bring us weather from the Gulf of Mexico, Hudson's Bay and
everywhere between. Hurricane Katrina passed over here after hitting New
Orleans.

The early settlers expected our climate to be similar to southern Europe's
at the same latitude, not deep snow and extreme winter cold more like
Scandinavia. Half of the Pilgrims died the first winter. Being retired I
don't have to drive in storms and can keep the wood stove going all day, so
I can enjoy the good weather and not be bothered by the bad. Your Canadian
air is very pleasant in summer.

[Bob La Londe]

Post by Bob La Londe

Post by Bob La Londe
...
I never was employed doing destructive testing, but I did spend a decade
or two doing low voltage communication contracting.  I learned there is
what they say, and there is what there is.  Usually what they say fell
short in my field, but sometimes it didn't.
When they say an IR motion sensor will detect motion at 90 feet they
mean if ambient is below 70F and the subject is large and is running a
fever.  LOL.  They don't say if ambient is 90+ its virtually worthless.
---------------------
Most of the testing was to find and reject or reclassify parts that
didn't meet specifications for companies that cared, or burn-in
testing to weed out early failures by operating at elevated
temperature for a week. The exact conditions were usually secret, I
had to provide a range of adjustment. Sometimes there had to be
provision for destructive failure, such as Chrysler Lean Burn engine
controllers with components not rated for possible under-hood
temperatures.
Before Congress mandated emissions and fuel economy standards that
needed electronic control to meet, the only electronic device in a car
was the radio which the auto makers bought, they had to hire new
engineers unfamiliar with the heat, water, dirt, salt and vibration,
who took time to learn. I had the partial advantages of military
electronic experience which solves those, in commercially unaffordable
ways, plus a hands-on apprenticeship in custom electro-mechanical
machine design. The engine compartment environment can be nearly as
challenging as military aircraft specs, consider a snow plow driver in
Alaska starting cold and diving full throttle into the deep snow in
front of the truck, or splashing through an icy puddle.
Heat in the South is another issue that's not so evident in Michigan.
I know what Atlanta is like in summer.

Bell Labs had material test sites down here in the Sonoran Desert for
environmental testing.  Death Valley may be the only place in North
America more hostile than the low Sonoran Desert.  They had panels setup
with material samples affixed out along the southern rail line right of
way.  Maybe they still do (if they are still some form of Bell Labs).  I
haven't checked in a long time.

Yes I used to ride year around in it too.

[Snag]

Post by Bob La Londe

Post by Bob La Londe

Post by Bob La Londe
...
I never was employed doing destructive testing, but I did spend a decade
or two doing low voltage communication contracting.  I learned there is
what they say, and there is what there is.  Usually what they say fell
short in my field, but sometimes it didn't.
When they say an IR motion sensor will detect motion at 90 feet they
mean if ambient is below 70F and the subject is large and is running a
fever.  LOL.  They don't say if ambient is 90+ its virtually worthless.
---------------------
Most of the testing was to find and reject or reclassify parts that
didn't meet specifications for companies that cared, or burn-in
testing to weed out early failures by operating at elevated
temperature for a week. The exact conditions were usually secret, I
had to provide a range of adjustment. Sometimes there had to be
provision for destructive failure, such as Chrysler Lean Burn engine
controllers with components not rated for possible under-hood
temperatures.
Before Congress mandated emissions and fuel economy standards that
needed electronic control to meet, the only electronic device in a
car was the radio which the auto makers bought, they had to hire new
engineers unfamiliar with the heat, water, dirt, salt and vibration,
who took time to learn. I had the partial advantages of military
electronic experience which solves those, in commercially
unaffordable ways, plus a hands-on apprenticeship in custom
electro-mechanical machine design. The engine compartment environment
can be nearly as challenging as military aircraft specs, consider a
snow plow driver in Alaska starting cold and diving full throttle
into the deep snow in front of the truck, or splashing through an icy
puddle.
Heat in the South is another issue that's not so evident in Michigan.
I know what Atlanta is like in summer.

Bell Labs had material test sites down here in the Sonoran Desert for
environmental testing.  Death Valley may be the only place in North
America more hostile than the low Sonoran Desert.  They had panels
setup with material samples affixed out along the southern rail line
right of way.  Maybe they still do (if they are still some form of
Bell Labs).  I haven't checked in a long time.

Yes I used to ride year around in it too.

It's only the last couple of years I haven't ridden year round . My
wife says I'm gettin' old , but I don't believe her . It's just that I
have so much here to keep me busy ... and well , wrasslin' an 800 lb
touring bike around the yard to where it's parked isn't as much fun as
it used to be . The planned gravel work may change that .

[Clare Snyder]

Post by Bob La Londe

Post by Bob La Londe

...

I think its more likely adjustment of the internal BMS depending on how
the larger battery is configured to make it larger.  For instance if it
has an extra bank of cells it can 100% certainly deliver more current.
Just like tying two car batteries in parallel gives you more current
capacity.  I expect larger cells might also be capable of more current
if the conductors are sized accordingly.
Bob La Londe
CNC Molds N Stuff
-------------------------------------
Beyond the BMS limits, the capacity and internal resistance depend on
details of the chemical formulation and physical structure, such as
particle size, which may be trade secrets. I've read that they can be
traded off depending on the intended load current, higher resistance for
greater capacity and vice versa.
https://www.linkedin.com/pulse/what-does-c-mean-lithium-ion-batteries-bruce-feng
Marine batteries are similar, the high capacity deep cycle ones for
trolling motors aren't recommended for engine starting current.

I think you are over thinking it. Sure changes in technology can make a
difference, but often larger battery packs are just larger. Quite often
when you dig into various mid to good quality battery packs you find
they have the same cells from the same manufacturer. Assembly quality
is an issue, as is the choice and programming of the BMS, but the cells
are the same.
I have a bit more experience with marine deep cycle lead acid batteries,
and I don't think its as big of a deal as you think. I've even run
combined usage with the base ground battery doing double duty as the
cranking battery and the ground battery for the trolling motor. I've
done it for years, and other anglers I know have done it for years
before me. Its a way to run a larger trolling motor when battery space
is limited. I did run four batteries in my current 20'10" bass boat
because I have the room for them. In my newest smaller acquisition
there is no space for 4 batteries, but I noticed it has a 36V trolling
motor on the bow. They have just been running it on 24V. Runs fine.
Just less power. I'll be converting it to the dual usage cranking
battery configuration as soon as I have enough play money to buy all new
matching batteries for that one. Could they get better life if
configured differently. Maybe. That all is a bit of a tangent though.
--
Bob La Londe
CNC Molds N Stuff

With cylindrical lothium batteries the cells are all pretty much the
same physical size regardless of their published capacity. All pretty
much induatry standard 18650 format. The difference between battery
PACKS of different capacities will be either the composition of the
cells or the number of banks. If limitted to the number of banks
capacity differences will be the cell capacity X1. X2, X3, or X4 -
with the physical size reflecting the difference.
Battery cell composition - different chemistries or different
construction, will give less distinct "multiples" af power and no
change in physical size. An 18/20 volt battery is composed of 5 cells
in series, 0r 2 series sets of 5 arranged in parallel, or 3 sets in
parallel - etc. For a 4Ah and 5Ah to be composed of the same cells the
5Ah battery would be 1/4 larger than the 4Ah - and would be capable
of producing 1/4 more capacity AND maximum current (assuming the
connector links are sized appropriately and heat shedding is adequate)

With lead acid batteries things get more interesting. The grid
design, link design, lead alloy, and acid capacity all come into play
(along with the separator material) before even taking case size into
account. (or acid strength). Basically the weight of lead in a battery
is a pretty good predictor of capacity - but whether that weight is
arrives at by plate thickness or plate density makes a BIG difference
- primarily by the difference in "paste" capacity.

Deep Cycle, SLA (Starting Lighting and Accessory) or Marine
(combination) are all designed and built differently.Whether flat
plate or coiled.
Real good "deep cycle" batteries are most often "pure lead" while
antimony or calcium alloys are generally used in SLA and Marine
batteries. Marine batteries are generally built to withstand more
vibration without degrading ling connections or dislodging the paste -
through both plate design and separator material. Some cheaper
batteries address the plate material issue by providing deeper "acid
wells" below the plates to allow more shed material to accumulate
without shorting the plates - at the expense of smaller plates - while
at the other extreme you get starved acid, or AGM (absorbed glass mat)
batteries there there is NO SPACE between the separator and the plate
- meaning no plate material can effectively leave the plates - and
ONLY the rquired amount of acid is contained in the battery - allowing
for maximum plate vol;ume and mass for the battery case dimension. AGM
batteries are highly vibration resistant, and pure lead versions make
ideal deap cycle batteries although not NECESSARILY suited for high
current output.

When sizing a "battery bank" endeavour to use the highest capacity
cells you can get, connected in series, rather than higher voltage
batteries connected in parallel - for a 36 volt pack use 6 big 6 volt
batteries in series rather than 2 packs of 3 12 volt batteries. The
6X6 is ONE BATTERY while the 6x12 volt solution is actually TWO
BATTERIES in parallel - with the associated load sharing and
interconectivity issues involved.


The same can be said with Lithium (or other chemistry ) Large cells
connected in series makes a much better traction battery than a couple
bushels of 18650 cells or double A cells bunched together into a
battery pack

[Jim Wilkins]

"Clare Snyder" wrote in message news:***@4ax.com...

When sizing a "battery bank" endeavour to use the highest capacity
cells you can get, connected in series, rather than higher voltage
batteries connected in parallel - for a 36 volt pack use 6 big 6 volt
batteries in series rather than 2 packs of 3 12 volt batteries. The
6X6 is ONE BATTERY while the 6x12 volt solution is actually TWO
BATTERIES in parallel - with the associated load sharing and
interconectivity issues involved.

----------------------------------

I've seen that advice several times and priced it out, finding that 12V
100Ah appears to be a sweet spot for price vs performance, in lead-acid and
lithium. Perhaps it would be different if I needed more than 50A from the
batteries.