Homemade Battery Packs

Batteries, Chargers, and Battery Management Systems.
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DrkAngel
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Re: Homemade Battery Packs

Post by DrkAngel » May 06, 2014 6:08 am

2004 vs 2010 Laptop Lipo

Capacity mapped 2004, 2006, 2008 and 2010 2160mAh cells.
2004 and 2006 are very similar, 2008 and 2010 are likewise very similar.

While very similar to the 2004 and 2006 productions, 2008 and 2010 productions have clearly defined differences.

Most notable is a shift in capacity bulges.
2004 vs 2010 comparison
Lipo 4320 (Dell) 2004-1010.jpg
Lipo 4320 (Dell) 2004-1010.jpg (65.37 KiB) Viewed 2725 times
Capacity bulges demonstrate a clear and universal .05V shift towards lower voltage.

This is likely due to some "formula" modification.

Surprisingly, all formulations still exhibit 4.02V and 4.15V as their optimal charge voltages.
4.02V as optimal for best longevity ~400% cycle life. (at a 20-25% capacity loss)
and
4.15V as optimal for most efficient capacity ... with a reasonable increase, ~150%(?) cycle life.

Max DOD has been shifted from >3.75V to >3.70V

Notes:
The 2004 capacity increase at 4.20V (Blue line) is a flaw due to unattended "final" set and forget charge.

Performed test from 3.50V to 4.30V, below and above any expected reasonable capacity, I felt it responsible to be thorough ... and check for the unexpected ... no surprises tho ...

See - Capacity Mapping (Optimal Charge-Discharge Voltages)
Last edited by DrkAngel on May 07, 2014 8:22 pm, edited 1 time in total.
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Re: Homemade Battery Packs

Post by DrkAngel » May 07, 2014 4:55 am

After capacity mapping the 2008 laptop Lipo cells, and noting the capacity bulge at 3.70V, I decided to discharge "fully" ... to check cell equalization at max DOD and to capacity check entire pack.
Amazingly, all banks were within ~1/100th V at 3.687V - 3.699V!
(Love quality control and durability of these cells)

Image

Test charges were through a "genuine" iMax B8, (Blue with chrome buttons), on "Lipo charge" setting.
Resultant bank voltage is a favorable 4.17V.

Metered recharge, 3.70V to 4.17V at 3A, was 24.264Ah.
Not as good as metered with alternate mAh meter but a good reference for future capacity tests with same iMax.

Cordless power tool pack rebuilds
Had some spare, same batch, new cells, so I built 2 -18.5V 4.32Ah Lipo power tool replacements for NiCd battery packs.
1st, I removed the individual cell fuses and was able to shorten cell length to fit nicely.
18.5V 4.32Ah replacing 18V 1.2Ah NiCd in Black & Decker FireStorm pack
Will test in B&D weed whacker and blower, blower has highest continuous drain.
and
18.5V 4.32Ah replacing 19.2V 1.6Ah NiCd in Craftman pack
Built 1 test pack for a buddy and he is presently testing before having me build more.

I did build a B&D test pack ... couple years ago ... but used, leftover, unmatched cells ... good success with partial discharges only.

I plan on testing one 3s2p "new" pack, with fuses removed, maximum C discharge rate.
Previous test w/fuses surged 4C then settled to 2C+ but blew fuses after a certain time ... I forget how long ...

12.6V 4.32Ah battery
12V 250w blower / 12.5V battery = 20A
20A / 4.32Ah = 4.63C (5C+ with sag?) continuous discharge with probable higher surge.
Will test for actual amp output, voltage sag, heat production etc. (25A digital V A W Ah meter)
Last edited by DrkAngel on May 09, 2014 8:31 am, edited 1 time in total.
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Re: Homemade Battery Packs

Post by DrkAngel » May 09, 2014 8:28 am

"New" 25.9V 25.92Ah full discharge - recharge test #2
Rode 37+ miles yesterday, drained cells to ~3.66V.
Recharge with alternate "genuine" iMax B8 (black with colored arrow buttons)
Recharge at "Lipo charge" 3.0A from 3.666V to 4.185V was 27.647Ah

That is 106.66% of rated capacity ... must have completely drained the 3.70V capacity bulge.

Will try to find some method to precisely compare accuracy of my iMax B8s.
But ...
I am very very happy with these 6 year old cells ... gotta try to find more!!!

3.695V - 4.170V = 24.264Ah (Blue iMax B8)
3.666V - 4.185V = 27.647Ah (Black iMax B8) + 3.383Ah

Will capacity map the RC Lipo, I have:
WinForce 5700mAh (I have 2s and 3s, will test 3s)
and
Winners Circle 2000mAh (have 3s and 4s, will test 3s)
* Preliminary test showed good capacity to 3.50V, so I will begin with cells at ~3.4V
will post up results here and full details in Capacity Mapping thread.
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Re: Homemade Battery Packs

Post by DrkAngel » May 14, 2014 9:09 pm

DrkAngel wrote: Will capacity map the RC Lipo, I have:
WinForce 5700mAh (I have 2s and 3s, will test 3s)
and
Winners Circle 2000mAh (have 3s and 4s, will test 3s)
* Preliminary test showed good capacity to 3.50V, so I will begin with cells at ~3.4V
will post up results here and full details in Capacity Mapping thread.
Tested up - capacity mapped - RC Lipo.
Mapping such different capacity, from the same power supply likely skewed results somewhat, but results posted up as "preliminary".
See -Capacity Mapping

New map!
WinForce 5700mAh "20C" RC Lipo Capacity Map
Image
Looks like the ideal candidate for a 3.90V charge limit with 800% the usable cycles!

Note: 0mAh at 3.42V is deceptive.
That is the voltage where I equalized cells before beginning test.
After preliminary discharge, cells varied between 3.18V and 3.42V ... it took minimal mAh to raise cells to 3.42V.
I fell confident in rating no appreciable capacity below 3.42V!
Last edited by DrkAngel on May 22, 2014 8:06 am, edited 1 time in total.
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Re: Homemade Battery Packs

Post by kje » May 21, 2014 8:01 pm

I made my 3s50p pack for my electric boat motor. First all in paralell:
20140517_224811.jpg
20140518_002628.jpg
Then in series and I had a nice laptop breefcase I could use:
20140518_025052.jpg
20140518_030408.jpg
At what voltage should I stop using this battery?

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Re: Homemade Battery Packs

Post by Skalabala » May 22, 2014 2:10 am

kje, looks nice :)
Stop using at 11V to 11.1V to save the life that is left in them.
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Re: Homemade Battery Packs

Post by kje » May 22, 2014 7:08 am

Skalabala wrote:kje, looks nice :)
Stop using at 11V to 11.1V to save the life that is left in them.
Thanks :) How many percent is left at 11V?

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Re: Homemade Battery Packs

Post by DrkAngel » May 22, 2014 8:12 am

Looks like you are using a large percentage of red Sanyo cells.
Here is the capacity map for Sanyo 2600mAh cells.
Image
A little learning is a dangerous thing;
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Re: Homemade Battery Packs

Post by Skalabala » May 22, 2014 2:42 pm

kje wrote:
Skalabala wrote:kje, looks nice :)
Stop using at 11V to 11.1V to save the life that is left in them.
Thanks :) How many percent is left at 11V?
With old cells I would say at 11V for 3S you have 0% left. Think 11.2V will actually be better especially when looking at the graph provided by Angel :mrgreen:
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Re: Homemade Battery Packs

Post by kje » May 22, 2014 5:38 pm

Thanks both of you. :) 11.2V under load or resting voltage?

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Re: Homemade Battery Packs

Post by DrkAngel » May 22, 2014 7:00 pm

kje wrote:Thanks both of you. :) 11.2V under load or resting voltage?
11.2V = "empty" voltage at rest.

With battery at resting ("empty") voltage, run motor at normal.
Measure voltage ... This will give you "empty" voltage under load.
A little learning is a dangerous thing;
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There, shallow draughts intoxicate the brain,
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I enjoy enlightening ... and enlivening the spirit of the innovators.

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Re: Homemade Battery Packs

Post by kje » May 23, 2014 5:13 pm

Ok, thank you. I'gonna solder a balancing plug to the pack so I can balance it now and then. I tested the battery with my electric trolling motor just some seconds, and it seems to work well. I'm curious on the amp hour rating and how well balanced the 3 cells is...

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Re: Homemade Battery Packs

Post by Skalabala » May 24, 2014 5:50 am

kje wrote:Ok, thank you. I'gonna solder a balancing plug to the pack so I can balance it now and then. I tested the battery with my electric trolling motor just some seconds, and it seems to work well. I'm curious on the amp hour rating and how well balanced the 3 cells is...
Check the sag on each cell, will give some indication on how happy they are!
Bit of topic. Me and two friends in a small rubber duck on a big dam with only a trolling motor and the battery of the car we used as transport far away from home...
Man let me tell you 3 hours of rowing was a nightmare!
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Re: Homemade Battery Packs

Post by DrkAngel » May 24, 2014 6:26 am

kje wrote:Ok, thank you. I'gonna solder a balancing plug to the pack so I can balance it now and then. I tested the battery with my electric trolling motor just some seconds, and it seems to work well. I'm curious on the amp hour rating and how well balanced the 3 cells is...
"Balance" function on a battery that large might take many days!
and
Will not "fix" any unbalance.
Much better - easier to re-shuffle some cells.

Begin with equal bank voltage at full charge.
After discharging reasonably ...
measure voltage of each bank,
mark voltage variance of each bank,
recharge,
add cell-cells to weaker-lower voltage marked bank.

or
Cut cell-cells from higher voltage bank, add to lower voltage bank.

Re-cycle and test again ... re-shuffle ... etc.

Updated INDEX May 2014
Last edited by DrkAngel on May 25, 2014 8:30 am, edited 2 times in total.
A little learning is a dangerous thing;
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There, shallow draughts intoxicate the brain,
And drinking largely, sobers us again.

I enjoy enlightening ... and enlivening the spirit of the innovators.

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Re: Homemade Battery Packs

Post by kje » May 24, 2014 10:41 am

Skalabala wrote: Check the sag on each cell, will give some indication on how happy they are!
Then I have to desolder the hole pack...?

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Re: Homemade Battery Packs

Post by kje » May 24, 2014 10:44 am

DrkAngel wrote:
kje wrote:Ok, thank you. I'gonna solder a balancing plug to the pack so I can balance it now and then. I tested the battery with my electric trolling motor just some seconds, and it seems to work well. I'm curious on the amp hour rating and how well balanced the 3 cells is...
"Balance" function on a battery that large might take many days!
and
Will not "fix" any unbalance.
Much better - easier to re-shuffle some cells.

Begin with equal bank voltage at full charge.
After discharging reasonably ...
measure voltage of each bank,
mark voltage variance of each bank,
recharge,
add cell-cells to weaker-lower voltage marked bank.

or
Cut cell-cells from higher voltage bank, add to lower voltage bank.

Re-cycle and test again ... re-shuffle ... etc.
Yes, I was planning to re-shuffle some cells after a while. :)
Is it not necessary with balancing plug on this large pack? Well, If it`s not necessary thats good news.... less work! :D

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Re: Homemade Battery Packs

Post by kje » May 25, 2014 12:57 pm

Can it be dangerous to not balance it?

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Re: Homemade Battery Packs

Post by 999zip999 » May 25, 2014 1:54 pm

You can just add cells to low string no cutting.
Maybe a 4.05v - 4.1v. or something, for single cell charger for balancing.
Do you have a watt, ah meter they are cheap you can check ea string with load or just test whole pack.
Before going out on the water without a paddle.

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Re: Homemade Battery Packs

Post by kje » May 25, 2014 4:58 pm

999zip999 wrote:You can just add cells to low string no cutting.
Maybe a 4.05v - 4.1v. or something, for single cell charger for balancing.
Do you have a watt, ah meter they are cheap you can check ea string with load or just test whole pack.
Before going out on the water without a paddle.
String = all the batteries wich is in parallel??

I don`t have a watt, ah meter but I can buy one. I could test each string with my Imax but it can only discharge with 1A. This batterypack is estimated to be 100ah so it will take 100 hours to discharge each string with 1A.

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Re: Homemade Battery Packs

Post by kje » May 27, 2014 7:31 am

My motor have a max draw at 55A. Do I need more vertical wires (the short wires) on the parallel strings for better current sharing?

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Re: Homemade Battery Packs

Post by kje » May 27, 2014 7:57 pm

Will this ebay watt meter save the amps used so I can see how my batterypack performs with my trolling motor?

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Re: Homemade Battery Packs

Post by teslanv » May 27, 2014 8:03 pm

kje wrote:Will this ebay watt meter save the amps used so I can see how my batterypack performs with my trolling motor?
Yes, that should do the trick. Pretty cheap.
This is the one I use:
http://www.amazon.com/High-Precision-Po ... =wattmeter

Note that all of these wattmeters will not "save" info after you disconnect the power to them, so they are only useful for one trip.
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Re: Homemade Battery Packs

Post by DrkAngel » May 27, 2014 10:06 pm

DrkAngel wrote: I believe I will attempt to build another 22.2V pack.
Previous 22.2V pack consisted of 40Ah+ of old re-re-recycled Sanyo cells and I rated as ... lack-luster - too wimpy! in performance.

Proposed build will consist of the same type Lipo cells used in 25.9v 22mph pack.
Instead of using the 12 side cells as an additional 7th bank they will add 2 cells to each of the 6s "bricks".
Same total capacity
7s12p = 25.9V 25.92Ah = .671 kWh
will become
6s14p = 22.2V 30.24Ah = .671 kWh
22.2V pack should be an enforced economical and "legal" alternative for my 2008 Trailz w/16T mod and my 2013 Trailz LS w/13T mod.

22.2V Lipo should outperform, or at least compare favorably with, 24V SLA.
SLA 24V controller w/~21V LVC should be perfect for the 22.2V Lipo.
Balance charge with cheap iMax B6 or equivalent ~$20
6A CC/CV charging with MeanWell S-150-24 ~$20 + shipping
And should provide 600% the range of the oem SLAbatts! ... at 1/2 the weight!!!

Oh ... and ...
5x the range of the $400 Currie Lithium alternative (6.14Ah)
3x the range of the $600 Currie Lithium alternative (9.6Ah)
22.2V 30.24Ah NOS Laptop Lipo ... ""100701" = 2010 July 01 dated cells.
I know, I know ... I said 22.2V was too wimpy!

But, I tried my latest 25.9V 25.92Ah battery build on my latest ...
2013 eZip Trailz LS w/13T motor sprocket ... cruised at 22-23mph.
Couple problems:
Exceeds "legal" - 20mph.
Running at +22mph strains the battery well past my recommended .5C.

Running the numbers ... 22.2V looks to cure both problems.
Took the 7th"s" and split it up between the remaining 6s.
Dropped top cruising requirement by 100w.

1st build using the newer black eZip "RMB" pack.
I had to chisel "ribs" out of pack, to provide proper clearance.
Used Formica as shelves to support cells.
Wedged a wooden block as additional support under lower cells-Formica.

Image

I did add a balance connector ... had the silicone 22ga balance connector anyhow ...
Just cause I could ... I balanced all banks to precisely 4.186V.
Ooh! Tried bleeding down a bank using jumper wires connected to ends of soldering gun tip. Worked pretty good ...

Image

Speed settled perfectly ... just a fraction under 20mph.

Testing now.
Ran 20 miles at 19mph+ and have all banks still at 3.84V.
Likely another 7-8 miles at 19mph?
Oh ... motor only, no pedal assist.
40miles plus @ 16mph?

Image

Will mod a MeanWell S-150-24 as 25V 6A charger.
The 24V 40mm fans seem a bit fast-loud so I tested with a 2watt 47ohm resister, in series, and resulted in a moderately quit fan with minimal resister heat.
Upgraded charging wire to 14ga for rapid charging ... if I care to try ...

Reread the post...
Sounds like I rebuilt my 25.9V into a 22.2V.
Separate build!
I still have both and need 25.9V for my 16T mod eZips.
Attachments
22.2V30Ah.jpg
(249.77 KiB) Downloaded 17 times
22.2V30AhB.jpg
Last edited by DrkAngel on May 28, 2014 7:28 am, edited 2 times in total.
A little learning is a dangerous thing;
Drink deep, or taste not the Pierian spring:
There, shallow draughts intoxicate the brain,
And drinking largely, sobers us again.

I enjoy enlightening ... and enlivening the spirit of the innovators.

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Re: Homemade Battery Packs

Post by DrkAngel » May 28, 2014 7:23 am

Kind of a work in progress ... when FireFox crashed.
Accidental posted up later.
Sorry ...

Here are some handy copy & paste items!

ºC ºF & ≥ ≤ ± $ ¢ £ € ¥ ƒ ¿ ? ! ¡ ² π ∑ √ + - ÷ ∞ • ¾ ½ ¼ µ ± ‡ † Δ Ω ™ © ® x² eco²
Last edited by DrkAngel on May 28, 2014 6:16 pm, edited 2 times in total.
A little learning is a dangerous thing;
Drink deep, or taste not the Pierian spring:
There, shallow draughts intoxicate the brain,
And drinking largely, sobers us again.

I enjoy enlightening ... and enlivening the spirit of the innovators.

New & Improved - Acronym Definitions

Index - Homemade Battery Packs - Updated - November 2015

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Re: Homemade Battery Packs

Post by kje » May 28, 2014 4:17 pm

teslanv wrote:
kje wrote:Will this ebay watt meter save the amps used so I can see how my batterypack performs with my trolling motor?
Yes, that should do the trick. Pretty cheap.
This is the one I use:
http://www.amazon.com/High-Precision-Po ... =wattmeter

Note that all of these wattmeters will not "save" info after you disconnect the power to them, so they are only useful for one trip.
Thank you! I bought it right away. :)
I also added a 60A fuse to my batterypack.

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