My Test of a Laptop Pulled 18650 - What's Your Opinion?

Batteries and Chargers Rechargeable Batteries
1

I have a set of 9 LG DB118650 18650 cells pulled from a used laptop pack. If I remember correctly, these were pulled from a 4 year old well used Dell battery pack which the user said was giving him reduced runtime. I labeled all 9 cells 1 to 9, recorded initial pulled voltage, charged up, recorded full charge voltages, and then recorded voltages 2 weeks later and then 5 months later. 8 of the 9 are very consistent, with the 1 odd one just slightly different. Of those 8 I have chosen 1 to evaluate further and here are the stats:

Initial pulled voltage: 4.11v
Fully charged: 4.17v
16 days later: 4.15v
5 months later (today 1/6/2014): 4.13v

I don't have a Hobby charger, so I used my EDC Convoy S2 with a 2.1A Nanjg driver to do a discharge test. I Placed the cell without recharging into my Convoy S2 and measured tailcap current @ 2.03A and it held steady there. I then put the tailcap on, put the light on high, and ran a timer. At 15 minutes the light was burning hot so I placed a fan nearby blowing across it to continue.

At 45 minutes I stopped and measured cell voltage @ 3.68v and current @ 0.83A and falling (it actually started higher, but the drop slowed around 0.83A). Put cell back in light on high and continued the timer.

At 58 minutes the low voltage flash kicked in and I shut the light off, quickly removed battery and tested voltage @ 3.61v, tailcap current of 0.48A and dropping like a rock. I let the cell rest 5 minutes and rechecked voltage @ 3.69v.

Then for comparison I checked tailcap current with a used Sanyo laptop pull @ 3.75v and it gave me a very steady 2.03A.

I realize I should have stopped my test at maybe 15 & 30 minutes for voltage and current, but I didn't. In any case, what is your evaluation of this LG cell (and very likely the same condition with the other 7 or 8 I have)? Do you think it has enough capacity to be worth keeping? Or does it seem low enough to just toss them? Perhaps another good test would be to see what current the cells put out with my direct drive Manafont Ultrafire XM-L P60 drop-in? Is that a better test?

BTW, my thought was to use these LG's in my new ENB power bank / mobile charger.

Thanks,
Garry

2

That depends on if their useful to you. Battery self discharge voltage doesn’t seem that bad to me. The capacity from what I gather above seems a bit low, 2000mah or lower. Looks like they may have built up a high internal resistance. You might try them in low drain devices and they possible could do much better. You know how much good new batteries cost, is it worth it to you.
Me personally, if its not cable of being drained at 3 amps or more with a decent capacity, its of no use to me. I don’t have any 18650 format devices with low drain.

3

Any cell is gonna be a bit off after 5 months(!), I wouldn't use its state after that long as an indication of much of anything. Fresh charge, do your runtime-until-warning-flash again with each cell, any problems will show up there.

4

Thanks for the input. It hardly seems worth it when I can buy good new unprotected batteries for around 6.50 each plus a little shipping. And if I'm really going for capacity in the power bank / mobile charger that don't much good for that either.

-Garry

5

They seem good, I never expect to see over 2Ah from a laptop pull. My test is simply to run each cell at 2.5amps for 6 minutes, then measure the voltage immediately after this and then another 10 minutes later. I then group into classes 1, 2, 2.5 and 3 based upon these voltages, (for immediate: above 4 = 1, above 3.95 = 2, above 3.9 = 2.5, above 3.85 = 3 I find this generally matches up to the overall state of the cell (internal resistance, % retained capacity etc). Anything below this I wouldn’t normally keep.

6

So you're really looking at how quick the voltage is sagging under a decent load? What voltage has sagged to 45 minutes later doesn't mean much then?

-Garry

7

There will be a greater difference with the longer test so small differences would be more easily seen, but if there's a significant difference in the shorter test there's not much point in running them all the way down.

8

I just finished charging up both the red Sanyo (from 3.75v) and the LG (from 3.69v). I don't know what the original capacity of either one is, but the LG finished an hour before the Sanyo! Both were charged in Miller ML-102 chargers (v.1 I assume, bought from IOS when they first came out). The LG only charged to 4.10v though while the Sanyo charged to 4.15v. (I swore these chargers would charge to more like 4.18v, but it could be that I'm using a different meter.) After the Sanyo finished, I put the LG cell on the charger the Sanyo came off of but it only went up to 4.12v.

-Garry

9

Aha, checked with another meter I happen to have with me (I'm at work) and according to that meter those voltages should be 0.03v higher than what the first meter read.

-Garry

10

Did my first laptop pull yesterday and it was 6 LG DB1'sfrom a Dell.2 strings of 3 in series,56Wh,11.1v so I reckon 2.5Ah

each ,nominal.The laptop was a breakdown,but it's a few years old.2.6 to 2.98volts direct but jumped to over 3.6v almost

immediately on charger.They were then storage charged to 3.7-3.8volts and were tested for internal resistance(DC only)

with a 4 and 8 ohm 1% résistors as per HKJ's sticky.I go 4 cells in the 220mohm range,one around 175,cell 6 gave 134,70

and 287mohm(0-4ohm,0-8ohm,8-4ohm).Meter readings weren't steady so I think no 6 is my error.

By comparison,I get(all at least 10% variation):AW IMR1.6Ah 60 and 70mohm,EFest IMR 1.5Ah,120mohm

(disappointing)

,NCR A;120,NCR B,90 unprotect,108 protect(2 each),PF;95,Yezl 2.4Ah;125,UR FM 2.6Ah,95-110 unprot,140 to 200mohm

protect.and of course,TF 2.5Ah blue,unprot;286mohm and protect UF grey;274mohm.

I think these LG D cells are fine for non overdriven lights,or matched,in multi cell lights.If anyone needs a translation of

all this gargon,just ask and I'll post it.

11

Laptop pulls seem like good candidates for a battery bank. Usually running in parallel and relatively low drain. Your tests seem to indicate the cells have a good bit of life in them yet.

I guess it depends on how many devices you want to top up from from your bank and how often you plan to charge it. We all probably instinctively want maximum capacity but do you really need it? For a week long hiking trip you'd probably want the highest capacity cells possible but for throwing into a daypack or briefcase and topping off each night, I use laptop pulls and never get close to totally depleting them. YMMV.

I also sometimes use an ML-102 with an XTAR UL1 USB lamp for room or camp lighting. Your cells would be perfect for something like this setup even if they won't suit a hot-rod XM-L light.

Then again, I hate discarding anything that I can repurpose.

12

@Billy X

I could use a translation. I am kind of new to all of this. So if you can, please post more info.

Thanks

13

My intention was to throw them in the power bank and leave them in my glovebox for emergency use along with a few USB cables. I was hoping I wouldn't have to charge them very often.

I ran the same cell (now fully charged, though only to about 4.15v) in the same light for 8 mins on high (2.1A draw), immediately checked voltage at 3.85v. Tailcap current was holding steady at 2.04A.

-Garry

14

Even brand new top quality cells aren't going to be well suited to that, long term storage for emergency use. They will all need to be used or charged regularly just because of the chemistry.

15

Four of my Sanyo laptop pulls (I have 6 and have only used 2 of them) were charged last year Jan. 11th 2013, tested voltage again Feb. 23, 2013 (with very little drop) and now about a year later have only dropped 0.14v on average (down to 4.04v now). These batteries have also been sitting in my garage so they have gone through some heat and cold. Seems like they're still holding pretty good capacity to me without being recharged often!

-Garry

16

Hi Gerrybunk,I hope you don’t mind a small hijack,it’s for a good cause,I was where Kodachrome is a year ago.
First the battery pack.It was marked 56watt hours and 11.1volts.There were 6 cells.Ohms law:resistance=volts/amps(R=V/I) and Power(watts)=V*I.
11.1/3.7=3 so strings of 3 cells in series,6 cells so 2 parallel strings.
I=P/V so 56Wh/11.1V==5.05Ah at 11.1V,so 2.5Ah per string at 11.1Vor 2.5Ah at 3.7V per cell.
For internal resistance,HKJ explains it so much better than I can there
We use 2 main types of lithium cell,lithium cobalt(ICR) and lithium manganese(IMR).The IMR’s are for high current drain and have low internal resistance.They are dearer with less capacity,than ICR’s,but are considered safer,so no protection.
ICR’s have optional electronic protection against too low voltage,too high current draw and too high voltige during charging.
Laptop pulls don’t have protection because we left it in the battery case we just distroyed to recover the cells :wink:
AW is a US battery manuacturer,E Fest is chinese.
Panasonic make the NCR18650A and B cells at 3.1Ah and 3.4Ah available protected or un prot/d.The Panasonic NCR18650PF
is a hybrid high drain,low res cell to compete with IMR’s,2.9Ah.The Yezl came with a cheap Yezl torch,as such,it’s not too bad.
Sanyo UR18650FM 2.6Ah has the lowest voltage sag under load of the “normal” cells and can beat some IMR’s,but can’t do high currents.Some of mine were an “as is” batch from fasttechwith the same de solder marks as the pulls.
UltraFire,TrustFire,Fandy,Spider….Fire,well,if 400mohms is dead,these left the factory with wrinkles and a Zimmer frame!
Hope this helps

17

Thank you Billy X, it really helps to have an explanation of all this info. It is much appreciated !!!

18

I finally got a chance to test these cells for current on a direct drive driver. I tested these with my Manafont Ultrafire direct drive P60 module. This module has been tested to pull about 4.5A with decent batteries. I chose 3 of the LG cells and 4 of the Sanyo cells. Here are the results:

LG Cell#, Volts, Amps Pulled

#1, 4.12v, 2.10A

#3, 4.14v, 2.18A

#4, 4.14v, 2.06A

Sanyo Cell#, Volts, Amps Pulled

#2, 4.17v, 4.22A

#3, 4.02v, 3.64A

#4, 4.13v, 4.06A

#6, 4.15v, 4.11A

So the LG cells barely put out 1/2 of what the Sanyos put out! Is this a good indicator of the remaining life of a used cell? Is this test showing I should just recycle these LGs and move on? Seems that way to me.

-Garry

19

The voltage makes a huge difference, you need to test them all at the same voltage to get comparable numbers.

edit: Is the voltage shown open circuit, or during the amp draw test?

20

I too have a handfull of LG 18650’s i salvaged from an old laptop that was roughly 5 years old. ( along with a number of sanyos, etc. from other laptops.
The Laptop would not even take a charge, and the battery pack appeared to be completely dead. I found only one cell in the pack that was down to 1.7 volts, thus shuting off the pack’s saftey circuit. the other 9 cells, all were above 3.6 volts, and charged up to 4.17 perfectly in my I4 Intellicharger. I did a simmilar test with one of the random cells using my Nitecore P25, and ran it on High-Mode for just over an hour before the P25 began flashing its % 50 battery warning indicator light.