50 Cell 18650 Charger and Capacity Tester

Batteries, Chargers, and Battery Management Systems.
Post Reply
hobostove   1 µW

1 µW
Posts: 1
Joined: Jan 25 2015 7:59pm

50 Cell 18650 Charger and Capacity Tester

Post by hobostove » Jan 25 2015 8:05pm

I'm thinking of building a large bulk charger and discharge capacity tester for recycled laptop cells. I've been using 2 BT-C3400's, which work well but can only handle 4 each at 1A. Would a bulk charger like this be of use to anyone else? It would charge and test actual capacity of 50 cells simultaneously in about 3 hours and display the results on an interactive lcd screen.

knighty   10 kW

10 kW
Posts: 535
Joined: Sep 13 2012 8:57pm

Re: 50 Cell 18650 Charger and Capacity Tester

Post by knighty » Jan 25 2015 8:53pm

to charge, I used a 40amp 4.2v meanwell psu (iirc it was 4v and I had to adjust it to 4.2)

and then 10 x 4 18650 cell holders from ebay, all in parralel

you need an amp meter inline, so you can watch it as you plug cells in to check for any bad cells (sudden big amp jump)



couldn't figure out a way to bulk test for capacity tho.... I was going to discharge a bunch of cells in series, and then check end voltage.... but never got around to it



p.s. 3 hours is very fast, to fully charge and then discharge a cell.... if you're doing 50 cells at a time no-one will be worried about speed... 12 hours would do (or whatever a 1c rate works out at)

999zip999   100 GW

100 GW
Posts: 9512
Joined: Jan 10 2010 1:40pm
Location: Dana Point So. Cal

Re: 50 Cell 18650 Charger and Capacity Tester

Post by 999zip999 » Jan 25 2015 11:49pm

Why would you waste time with used cells. It enough work and time with new cells. The risk of used old cells for an ebike pack. I mean what would you use them for.

diggler   1 kW

1 kW
Posts: 308
Joined: Mar 25 2014 12:12am
Location: Twin Cities, Minnesota, USA

Re: 50 Cell 18650 Charger and Capacity Tester

Post by diggler » Jan 26 2015 3:25am

here is the way I did it. I got all my info from Drkangel's thread http://endless-sphere.com/forums/viewto ... t=drkangel

Here is my thread for my recent build where I talked about killing time and working on those 1000 used cells I got 10 months ago..
http://endless-sphere.com/forums/viewto ... 85#p993221
basically 30s hooked to two 60w bulbs. So 120v discharging at 120w equals 1 amp. So every hour is 1Ah of capacity.
You first have to charge them and let them sit for a month or so to see which ones self discharge. Then capacity test.
Capacity testing takes a while. First you hook up 30 cells or pairs or 3 packs. (how every they come outta the laptop battery, I didn't cut them into individual cells). Then when one gets depleted you stop timer, unplug lights, write down the time, replace the depleted one with a ready to test one, write down what time you stared testing that one(from the timer/stopwatch, I used an app), then connect lights again and start timer. After the first one you pretty much just get 2 or 5 minute brakes in between checking voltages. You just check all the cells with a dvm. I put a check on them when they get to 3.60V and take them off at 3.55V. It may take 4hrs to test 30 cells or less if your cells are low on capacity. DrK solders all his connections. I used alligator clips. I couldn't picture soldering every 2 min. He had good used cells when he did his. YOU DO HAVE TO WATCH OUT FOR THE POSITIVE SIDE THOUGH WHEN YOU CONECT WITH ALLIGATOR CLIPS( IF POSIBLE LEAVE A TAB TO CLIP TO) BECAUSE THE CLIP CAN SHORT TO THE CASE IF THE WRAPPER IS SCRATCHED TO REVIEL THE BARE METTLE. Just be carful. I did 1000 this way and I did have it happen a couple time but it's usually right away when you hook it up.

P.S. you might want to get some HK lipo to get you rolling if you already have everything ells for you build. It's really not that expensive compared to the ebike batterie packs with bms's and chargers. O and if your still going to do your lappy cells I would highly recommend getting a menwell s 150 and modding it to do less volts. I really wouldn't worry about the amp mod it doesn't ever seem to push over 30 amps anyway.
Last edited by diggler on Feb 15 2015 11:45pm, edited 2 times in total.
GAS ELECTRIC FAT BIKE 49CC/3000W MXUS V1 18s Lipo 18 Fet BUILDING...http://endless-sphere.com/forums/viewto ... =6&t=65638
600W CAPACITIVE SPOT WELDER BUILDING... http://endless-sphere.com/forums/viewto ... =2&t=66466
HOLANDIA BEACH CRUSER 1000W 9C ?TURN REBUILDING... no thread yet.
Next project will be 18" Iron Horse hard tail mid drive

titooon2014   10 mW

10 mW
Posts: 22
Joined: Oct 01 2014 2:45pm
Location: France

Re: 50 Cell 18650 Charger and Capacity Tester

Post by titooon2014 » Jan 26 2015 3:26am

999zip999 wrote:Why would you waste time with used cells. It enough work and time with new cells. The risk of used old cells for an ebike pack. I mean what would you use them for.
Not sure about hobostove, but I can see many reasons myself :
- free or almost free (we can't all make the $$$ American make)
- Reuse means much less impact on the environment for such a product. Ever wonder who dig your lithium and what are their working conditions, and where are your still functional cells going when you throw them ( I'll give you a hint, at the moment lithium is not recycled )
- it takes time to work on used cells, but what if this time is actually enjoyable ( i love soldering!). I'ld rather "waste" my time on working cells than buy brand new cells which don't really provide me any added value in my applications.

999zip999   100 GW

100 GW
Posts: 9512
Joined: Jan 10 2010 1:40pm
Location: Dana Point So. Cal

Re: 50 Cell 18650 Charger and Capacity Tester

Post by 999zip999 » Jan 26 2015 11:52pm

Those pretty wrapped cells can be very dangerous. They are very much alive and can make big fire. So this must be done in a safe place. Used in a low wattage motor.
When done.
I mean they do have a cycle life that a good charge can't reverse.

diggler   1 kW

1 kW
Posts: 308
Joined: Mar 25 2014 12:12am
Location: Twin Cities, Minnesota, USA

Re: 50 Cell 18650 Charger and Capacity Tester

Post by diggler » Feb 10 2015 3:43am

(we can't all make the $$$ American make)
You should put where you live so people know how to source for you.

How's it going with your tester?
Did you read Drk's thread it really has everything you need to know to make a battery out of used sells in it.
It was the first thread I read. I read it last winter and it took me like a month! :lol:
And that was when it only had 38 pages.

It would be really nice to have an automatic capacity tester.
I've thought about getting 30 of those $2 low voltage alarms.
But if you could just load even 4 in each bank then get it to record the time it was discharging while switching to the next in line would be mint! It would be even better if it printed it out on the cell then spit it out. You could walk away and come back an hour later and find a box of sells with there capacity written on them. Then you'd just have to make sure the machine was kept fed.

But I think as far as charging go's you should just bulk charge.
The s-150-5 meanwell is cheap and the mod to get the voltage in the range you need is easy.
Even for a noob like me.
Stock the voltage go's from 4.5 to 5.5. After you put 1 k resistor in series to R25 it go's from 3.8 to 4.33V
GAS ELECTRIC FAT BIKE 49CC/3000W MXUS V1 18s Lipo 18 Fet BUILDING...http://endless-sphere.com/forums/viewto ... =6&t=65638
600W CAPACITIVE SPOT WELDER BUILDING... http://endless-sphere.com/forums/viewto ... =2&t=66466
HOLANDIA BEACH CRUSER 1000W 9C ?TURN REBUILDING... no thread yet.
Next project will be 18" Iron Horse hard tail mid drive

diggler   1 kW

1 kW
Posts: 308
Joined: Mar 25 2014 12:12am
Location: Twin Cities, Minnesota, USA

Re: 50 Cell 18650 Charger and Capacity Tester

Post by diggler » Feb 15 2015 3:20am

I've been thinking more about your idea and I don't see why this wouldn't work.
https://endless-sphere.com/forums/downl ... ?id=109591
If you didn't want to do that many than just get one.
It's called a dynamic balance charger.
I think you can set it up to cycle each cell. (so it can be your charger and tester)
You will still have to do self drain test.
There is other dynamic balance chargers too.
READ THIS thread. https://endless-sphere.com/forums/viewt ... 75#p738926
GAS ELECTRIC FAT BIKE 49CC/3000W MXUS V1 18s Lipo 18 Fet BUILDING...http://endless-sphere.com/forums/viewto ... =6&t=65638
600W CAPACITIVE SPOT WELDER BUILDING... http://endless-sphere.com/forums/viewto ... =2&t=66466
HOLANDIA BEACH CRUSER 1000W 9C ?TURN REBUILDING... no thread yet.
Next project will be 18" Iron Horse hard tail mid drive

User avatar
DrkAngel   100 GW

100 GW
Posts: 5343
Joined: Dec 15 2010 11:14am
Location: Upstate-Western-Southern Tier NY. USA

Re: 50 Cell 18650 Charger and Capacity Tester

Post by DrkAngel » Feb 15 2015 4:49pm

I began linking cells with small neodymium magnets (8mm discs) and bits of steel wire.
Much easier to replace-change cells.
No more soldering, till pack construction.
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 - December 2019

EBike Toolbox - Bargains! $

Endless Sphere Wiki - Lost?

diggler   1 kW

1 kW
Posts: 308
Joined: Mar 25 2014 12:12am
Location: Twin Cities, Minnesota, USA

Re: 50 Cell 18650 Charger and Capacity Tester

Post by diggler » Feb 15 2015 11:40pm

yah I haven't read your thread since last winter when I read all 38 pages at that time.
Other than soldering when testing (and maybe charging and discharging to slightly different voltages), I've followed your method to the t. I thank you for all your hard work. I'm just now building an actual pack out of them. :oops:
But since I'm not so pretty good at soldering and I got all the guts for a kick ass 600w capacitive spot welder from a guy at church, I'm building that first to assemble my packs.
http://endless-sphere.com/forums/viewto ... 5#p1006698
Here is where I'm at now.
I plan on building four 15s ?ah (hopefully 10ah), packs for my hollandia commuter with a 9c 1000w DD hubby.
I just got a couple 60v dedicated controllers for it. One was custom made for me with 15 4110's! and custom %'s for the three speed switch! I'm pretty exited if you cant tell. :lol:
GAS ELECTRIC FAT BIKE 49CC/3000W MXUS V1 18s Lipo 18 Fet BUILDING...http://endless-sphere.com/forums/viewto ... =6&t=65638
600W CAPACITIVE SPOT WELDER BUILDING... http://endless-sphere.com/forums/viewto ... =2&t=66466
HOLANDIA BEACH CRUSER 1000W 9C ?TURN REBUILDING... no thread yet.
Next project will be 18" Iron Horse hard tail mid drive

User avatar
zzoing   10 kW

10 kW
Posts: 732
Joined: Feb 01 2008 12:26am
Location: Fr SE

Re: 50 Cell 18650 Charger and Capacity Tester

Post by zzoing » Feb 16 2015 1:11am

Someone on YT made an 8 cell capacity charger.

there's alot of ones for used laptop cells. I thought it was nonsense but then i saw how rhinoasupergenius gets his: he finds an ebay seller with preferably new, sealed, laptop battery packs for celeron laptops from 2007, or so, he sais best if they are from the last decade...

he buys one new pack, with 12 cells or so per laptop battery, he tests their capacity, and if he likes them, he buys the other 120 cells or whatever from the same ebay seller, they arrive all new in box, not used. that's pretty cool. if it's official 2006 inspiron PC laptop batteries, someone happens to have 20 packs of, it can be 1/4 the price to buy the cells.

diggler   1 kW

1 kW
Posts: 308
Joined: Mar 25 2014 12:12am
Location: Twin Cities, Minnesota, USA

Re: 50 Cell 18650 Charger and Capacity Tester

Post by diggler » Feb 16 2015 4:13am

yah I got mines from a recycle center and they are of every different variety.
Surprisingly I still got a bunch of pairs at 3.5 ah and up out of the deal.
I first started collecting slightly used laptop batteries on ebay. Then I got 200 lbs of used batteries at the recycle center.
Between the two sources I have over 1000 cells.
I paid WAY too much but he said the next time it would be cheaper as long as I bring him the bad ones.
Don't know if I'll do it again, but I'll be all geared up now if I do. :lol:
GAS ELECTRIC FAT BIKE 49CC/3000W MXUS V1 18s Lipo 18 Fet BUILDING...http://endless-sphere.com/forums/viewto ... =6&t=65638
600W CAPACITIVE SPOT WELDER BUILDING... http://endless-sphere.com/forums/viewto ... =2&t=66466
HOLANDIA BEACH CRUSER 1000W 9C ?TURN REBUILDING... no thread yet.
Next project will be 18" Iron Horse hard tail mid drive

User avatar
DrkAngel   100 GW

100 GW
Posts: 5343
Joined: Dec 15 2010 11:14am
Location: Upstate-Western-Southern Tier NY. USA

72 & 40 Cell 18650 Charger and Capacity Tester

Post by DrkAngel » Feb 16 2015 12:41pm

Probably the same source as rhino ... guy, got 13 NOS - returns(?), 12packs of cells.
Opened 12 and got 6 SONY and 6 Sanyo, kept 1 in case I ever got the same laptop.
Bulk charged them all then rigged in series for a discharge capacity test.
One brand at a time, I rigged as 18s4p and discharged through a Volt, Amp, Watt, mAh meter.

Image
This allowed me to vary discharge, started with a 100w bulb and a 150w small heater.
(Yes, many 120V AC devices run OK at a reduced DC voltage)
With the mAh meter, powered by secondary battery, it is possible to remove cells as they near "empty" (3.60V?).
Just mark mAh on cells, as removed.

Ran SONY in one batch - all very close in capacity
and SANYO in second batch - 3 12 packs identical , 2 slightly less and 1 slightly more.

Perfect!
9 banks of 8 Sony + 4 Sanyo = 9s12p 33.3V 31.2Ah pack ... that fits in the eZip OEM pack.
If I remember correctly about $90 for a 1kWh battery!

Tested another batch at 20s2p that weren't of near equal capacity so required closer monitoring and frequent cell removal.
Cells charged in parallel (1s40p) to insure identical starting voltage.
(Held together with 8mm magnet discs)

Image
$12 V-A-W-Ah meter had a 90V rating, so I limited to 20s ~84V.

See - Bulk Capacity Testing

Tip: put laptop packs in freezer.
When cold, heavily tap on seam to crack open plastic cases, very small hammer, etc., I have used a 3/4" wrench or large-heavy screwdriver handle with good success.
Let warm to room temperature before charging!
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 - December 2019

EBike Toolbox - Bargains! $

Endless Sphere Wiki - Lost?

Post Reply