Homemade Battery Packs

[fredsparkle]

Hi!

Nice job on the battery pack!

However I would suggest to move the battery into the triangle of the bike frame like I did if you have enough room. It's not hard, and the results are amazing, your bike will feel much more safe and balanced to ride. I was having problems with the toolbox in the rear rack, especially on bumpy roads (even small bumps).
You can see what I did on my bike here viewtopic.php?f=3&t=35289&start=30#p589979 or on my website in the signature.

Thank you, I looked at your post and it looks great. I will shortly have three battery packs, so being able to swap is good. Also the frame space on my bike is not a neat triange like it is on yours, so really don't have the room.

I am also waiting to see what final capacity my pack levels out at; as it still seems to be climbing as it gets more use.

[DrkAngel]

A few months ago I "patched" one of my 18650 Li-ion packs with cells of a different manufacture.
All original cells were of same type, capacity and manufacture.
I added a pair of cells to the weak bank of cells.
Non balanced charging still produced good matched voltages at "full" and "empty".

But ... when I did a balance charge, the "patched" bank showed a noticeably higher voltage during charging.
As soon as charging was stopped the voltages were nearly equal.
The problems were that:
1. Charging stopped when the patched bank reached a false "full".
2. If allowed to fully "balance", the patched bank would be noticeably undercharged.

So ... once again ... "best results are obtained using cells of like manufacture, capacity, condition etc."

On the other hand the non balance charging produced excellent results ... no problems!

My "patch" was a bit of an experiment ... with mixed results. 1 more thing learned ...
I will disassemble the weak bank and repair with matched cells.

Update !
Opened up my pack, for proper repair and removed my "patch job" (additional cells tacked onto a weak bank).
Got ready to separate the bad bank for testing and matched cell replacement.
Noticed a cracked solder connection, re-soldered it.
Did a balance charge, then a full cycle.
Result ... back in the pink! Good as my first tests.
Matched within 1/100th of 4.18V (29.2V) & within couple hundredths at 3.7V (26V).

[DrkAngel]

I did mention previously ... somewhere, that my iMax B8 was unreliable when charging a single cell, or bank.
It allows too high a voltage!

Well, I should have heeded my own warning.
After rebuilding a pack, I decided to "tune" 1 bank and forgot to keep an eye on it.
Voltage measured 4.36V on the single bank!, and it was still charging!
One pair of cells was hot (120F w/optical IR meter) another warm (+100F).
I removed charge and cut hot cell from "bank", and separated other cells.
Next morning, cell voltages ranged between 4.12 and 4.16V, down from their typical 4.20V post charge voltage.

Yup! Cooked um!

Important!
Monitor all functions of a new charger! (Until confirmed accurate)

[bonald]

Here's mine. Still work in progress, 14s12p, at 12p most of them gives around 20ah when discharged to 3.0v. Batteries are from 4 years old Toshiba laptops. Those are panasonic cells, I also have a bunch of sanyo.

[DrkAngel]

I would highly recommend that you not discharge below a resting voltage of 3.6V!
Below that voltage there is minimal mAh and every deep discharge is damaging, to capacity, and cycle life.

[spuzzete]

Hi guys,

I made a video with my method for testing the batteries.




Let me know what you think.




P.S. Thanks DrkAngel for your help.

[bonald]

Can someone tell me whats wrong with cell #7 and #8 ?

[DrkAngel]

I picked up a few Genuine MeanWell S-150-24 switching power supplies.
Decided to play and came up with a 29.4V 5A battery charger for my 7S 25.9V Li-ion packs.
Charger is set to 29.1V = 4.15V per cell-bank.
(Externally, fully adjustable as 4.10V - 4.20V + or -)

MeanWell (Mean Well) S-150-24

29.4V 5A.JPG (48.99 KiB) Viewed 959 times

"Modded" up from 24V and down from 6.5A.

It was necessary to downgrade and limit amperage, to prevent overheating and self destruction.

Still working on a "full" indicator.
Ampmeter would work ... looking for an affordable solution.

See - MeanWell Mods - S-150-24

[DrkAngel]

7S, 29.1V, 5A + 5A = 10A Charger


Modular components add great flexibility!

See - MeanWell Mods - S-150-24

[Kin]

I like how you made use of the LED hole

Those little extension coverings are nice, nothing I've seen before on the clone meanwells. An extra touch that makes things cleaner.

[spuzzete]

Great job DrkAngel!

Very neat!

[hillzofvalp]

I think this is An appropriate place to advertise since there are a number of 18650 builds, but feel free to suggest I remove this post. I have 200-300 new 18650 cells in boxes of 30. They are sanyos. viewtopic.php?f=31&t=42800

[DrkAngel]

I like how you made use of the LED hole

Those little extension coverings are nice, nothing I've seen before on the clone meanwells. An extra touch that makes things cleaner.

These were all NEW! Genuine! MeanWells!
Yeah, I know ... An unbelievable bargain!
Less than $3.50 each ... delivered!
100+ sold in a few hours.

All Gone!
Don't ask!

Power cord socket has an externally accessible fuse.

I used a 2 wire voltage gauge connected to the power rails.
Plug into battery - gives pack voltage.
Then turn power switch on to charge.

Much less of a connection spark if charger is powered on 1st ... tho.

[xmasta]

Hi all,

First, thanks for drkangel for running this show and everyone else who contributed with some really good information, I too now r tearing down lappy packs and putting together something..
well, configuration will depend on how much good cells i'm going to get

Anyway, i'm posting because of a question that i didnt see coming up in the thread, I mostly have lenovo packs and some of them have confusing markings.



5.2 would make them cells to be 2600mah, but 4.53 comes up with some funky 2265mah .. ?

I'm confuse! Not all of them are marked in this confusing way now i wonder, do i have a lot of 2200 in my hand or 2600 ..

SE US18650GR is written on them, thats the only part that gives results in google, suggesting sony 2200? (second line is "T 8A1230I24T")

thanks in advance for your input, also if anyone knows, are those cells good? in the world of 18650 cells kindof.

[xmasta]

I guess it's better to ignore the confusing stuff on the battery if there's stuff written on cells and believe information that google provides using cell markings?
Seeing many different lenovo packs with two different capacity on them, one nominal one .. PSE? (circular logo) PSE being lower.

[spuzzete]

Hi all,




5.2 would make them cells to be 2600mah, but 4.53 comes up with some funky 2265mah .. ?

I'm confuse! Not all of them are marked in this confusing way now i wonder, do i have a lot of 2200 in my hand or 2600 ..

SE US18650GR is written on them, thats the only part that gives results in google, suggesting sony 2200? (second line is "T 8A1230I24T")

thanks in advance for your input, also if anyone knows, are those cells good? in the world of 18650 cells kindof.

Where did you get 4.53?

Even if the batteries are from the same brand the cells inside may be different. The number written on the outside of the pack should match che capacity of the cells inside the pack.

[xmasta]

Where did you get 4.53?

Even if the batteries are from the same brand the cells inside may be different. The number written on the outside of the pack should match che capacity of the cells inside the pack.

Photo 21.09.12 3 15.42.jpg (108.36 KiB) Viewed 1234 times

Photo 21.09.12 3 16.13.jpg (134.41 KiB) Viewed 1234 times

Photo 21.09.12 3 17.31.jpg (162.6 KiB) Viewed 1234 times

three different type laptop batts for different laptops, all having double capacity numbers.

[xmasta]

I think this should go out as a warning, because some ppl may not even notice the second value, I didnt at first.
So they may label their cells wrong and end up with very uneven and bad pack.
So I think good advice would be to check your lappy packs for two values and google your cells when markings are available to be sure.

[DrkAngel]

Likely ...
The one "rating" is the rated capacity of the cells.
The second rating is packs designed "rating".

The difference being that the pack manufacturer restricts maximum and minimum voltage ...
So as to prolong durability and lifespan!

4.1V per cell might provide double the life cycles compared to 4.2V ...
at a 5% reduction(?) in output!
Another 5% by stopping at 3.6V, instead of draining below 3.5V.

Near "full", and "empty", Li-ion cells store a very low percentage of energy.

If 3.6V - 4.1V = 100% recommended capacity (20% capacity per 1/10th V - averaged) ...
Discharging-charging 3.5V - 4.2V (110% recommended capacity, 5% per added 1/10th V)...
Hardly seems worth it ... for the wear and tear damage it causes!
*Based on measured capacity of the LiCo lipo I've been using lately.

[DrkAngel]

25.9V 25.92Ah pack, built by recycling laptop Lipo cells is nearing retirement.

After 1 1/2 years,
2 Summers,
about 4500 miles,
hundreds of recharges,
I'm about ready to retire my eZip Lipo rebuild.

Capacity has reduced noticeably!
Understandable.
Especially considering that all the cells were pulled from defective packs, the ones that would not charge properly!
Not that it is worthless!
It still gives me more than double the range of the oem SLA pack.

I think it is time that I re-build using my "good" cells.
Also I plan on adhering to a reduced charge-discharge voltage range.
These cells demonstrated a +90% capacity between 3.6V and 4.1V.
I'm certain that my initial 4.2V charging regime had a needlessly damaging affect.

Will try to add, and document, improvements.

[DrkAngel]

I think it is time that I re-build using my "good" cells.
Also I plan on adhering to a reduced charge-discharge voltage range.
These cells demonstrated a +90% capacity between 3.6V and 4.1V.
I'm certain that my initial 4.2V charging regime had a needlessly damaging affect.

OEM, laptop & external chargers, only charged to 4.1V.


Discharge map constructed using - MAh per 100thV discharge test

I am tempted towards an even tighter voltage range!
3.7V - 4.05V takes advantage of the "beefiest" area of the discharge profile.
It also leaves a healthy "emergency reserve", for "limping" home.

LiPo Bulge.JPG (10.47 KiB) Viewed 1091 times

Be aware! These results are for a specific cell type-formulation and might have no relation to other brands-types-formulations!

Also! I just posted my MeanWell latest success - Meanwell S-150-24 in Series - 37V 7A Li-ion charger.

[FastDemise]

Using some A123 1100mAh 18650 cells. It's a 4s7p configuration to replace my lead battery. Works great.




This is the battery while the motorcycle is at idle.

[DrkAngel]

I finally acquired a 30V capable voltmeter with 100ths V capability.
Combined with a cheap Ah meter, I was able to measure AHs on my recycled Lipo pack build. (Lithium ion (cobalt))
7S, 25.9V, 25.92 (rated) Ah
18.4Ah - (25.9V-29.4V) = 3.7-4.2V = 70% of rated

I decided to determine additional capacity added by various charge voltages.
1st - charged pack to 28.7V = 4.1V per cell
2nd - charged pack to 29.05V = 4.15V per cell (+1.06 Ah) 5.76% of full charge
3rd - charged pack to 29.4V = 4.2V per cell (+.79 Ah) 4.3% of full charge
(4.1V to 4.2V = 1.85Ah, 10.16% capacity. )
Note - Ah recorded when charge rate diminished to .01C = .15A

Charging to 4.1V, instead of 4.2V, loses almost exactly 10% of full capacity.
Worth it for an estimated doubling + of life cycles?

I know that my pack has deteriorated over the past few hundred cycles, but I was surprised to see that it still provided almost 300% the energy of the oem eZip pack (SLA).
(SLA - 10Ah discharged in 1 hour outputs a pitiful 6.14 Ah)

Rebuild will take advantage of a 4.1V maximum charge.
I also will test capacity and condition of individual cells ... stringently.
My confidence in "bulk charging" has grown to the degree that I might forgo the use of an external balance connector.
The 4.1V average charge leaves a large safety margin!
However, a schedule of internal checks will be maintained!

I guess ... now, I must measure the Ah between 3.5V - 3.6V - 3.7V.
First I must recheck low voltage levels and possibly "bottom balance"...
Due to it's deterioration, I have been limiting discharge to an averaged 3.7V.

[DrkAngel]

I finally acquired a 30V capable voltmeter with 100ths V capability.
Combined with a cheap Ah meter, I was able to measure AHs on my recycled Lipo pack build. (Lithium ion (cobalt))
7S, 25.9V, 25.92 (rated) Ah
18.4Ah - (25.9V-29.4V) = 3.7-4.2V = 70% of rated

I decided to determine additional capacity added by various charge voltages.
1st - charged pack to 28.7V = 4.1V per cell
2nd - charged pack to 29.05V = 4.15V per cell (+1.06 Ah) 5.76% of full charge
3rd - charged pack to 29.4V = 4.2V per cell (+.79 Ah) 4.3% of full charge
(4.1V to 4.2V = 1.85Ah, 10.16% capacity. )
Note - Ah recorded when charge rate diminished to .01C = .15A
...

I thought it might be illuminating to gauge the capacity of my lithium-ion (Cobalt) Lipo pack.
Method -
Begin with cells at 3.5V (my recommended minimum voltage)
Precisely charge to 3.6V - measure Ah needed
Repeat at .1V intervals until 4.2V (my recommended maximum voltage)

Tools -
MeanWell 24V bulk charger (19.8 - 29.8V adjustable)
30V 4 digit volt meter, 100ths capable
Ah meter

I discharged my 25.9V recycled Lipo pack to 24.5V.
Then precisely equalized the cells at 3.50V.
I applied charge with MW (MeanWell) set to:
25.20V (3.60V) - full charge required .27Ah
25.90V (3.70V) - full charge required .53Ah
26.60V (3.80V) - full charge required 3.87Ah
27.30V (3.90V) - full charge required 3.15Ah
28.00V (4.00V) - full charge required 4.60Ah
28.70V (4.10V) - full charge required 4.10Ah
29.40V (4.20V) - full charge required 1.85Ah
----------------------------------------
Total. .................... 18.37Ah
Ah capacity previously confirmed with -
iMax B8 full charge ..... 18.4Ah

I was both disturbed and inspired at the lack of capacity below 3.7V

With these cells ... discharging below 3.7V is needlessly damaging.
Almost 90% of the usable Ahs is between 3.7V and 4.1V.

Of course, more precise measurement should be made near 3.7V & 4.1V!

Remember! Every formula of battery has a different discharge profile.
Other lipo have displayed excellent capacity even to 3.4V.

PS Re-balancing-equalizing, with cells at 4.1V

Better chart?
24.50V (3.50V)
charge .27Ah =
25.20V (3.60V) -
charge .53Ah =
25.90V (3.70V) -
charge 3.87Ah =
26.60V (3.80V) -
charge 3.15Ah =
27.30V (3.90V) -
charge 4.60Ah =
28.00V (4.00V) -
charge 4.10Ah =
28.70V (4.10V) -
charge 1.85Ah =
29.40V (4.20V) - f
----------------------------------------
Total. .................... 18.37Ah

[arkmundi]

I thought it might be illuminating to gauge the capacity of my lithium-ion (Cobalt) Lipo pack....

Thanks for that! Question: for ah capacity, you find that during charge and/or discharge and how exactly?? Also, has anyone does this kind of reference capacity test for an A123 AMP20 li-ion? Regards.