some 18650 Li-On battery tests 0,5C (Updated 2A 4A constant Load)

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MatajumotorS

MatajumotorS

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Recently took some capacity tests of my 18650 cells. I tested 2x AW flat-top cells, 2x AW button-top cells (2200mAh), 2x TrustFire cells (2500mAh), and one cell harvested from old laptop PC (unknown capacity).
All cells were charded from same charger to 4,21V (other DMM showed 4,19V). 4 AW cells i charged in paralel to enshure the same state of charge.
As the load, i used "semi" constant current load based on LM350 in current source mode, set to 1,2A. "Semi" constant - because @ 3V it drops to 0,9A. I am working on constant current load adjustable to 10-15A and min voltage as low as 1,5V.

And here is the graphs: larger picture HERE
18650-test-1-small.JPG


All AW cells were used in one light, isn't it strange? - so big diference? See the cell AW3 and AW4, they are almoust identical, only the internal resistance of one is lower.
 
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Re: some 18650 Li-On battery tests 0,5C

Nice test. Thanks for taking the time and effort to do them:thumbsup:

Sverre
 
Re: some 18650 Li-On battery tests 0,5C

I will do more testing, when the "contant current load" will be finished.
 
Re: some 18650 Li-On battery tests 0,5C

MatajumotorS said:
I will do more testing, when the "contant current load" will be finished.
Click to expand...
Finished my Constant Current Load HERE :twothumbs

test-setup.jpg


Now i will continue Battery testing, Here are first results:

Tested 2x AW18650 2200mAh cells purchaset on 02.2008 two discharges and 2x TrustFire 18650 2400mAh purchased on 03.2008 two discharges. All cells charged on one charger.

Here are 2Amp constant discharge curves and calculated capacity.

Lottery or what ;)

Full size HERE or click on pic.
 
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Re: some 18650 Li-On battery tests 0,5C (Updated 2A constant Load)

As there was some interest, taked 4A discharge test for one TrustFire (starting 4,18V) and one AW 1650 cell (starting 4,20V). Both cells heated up to about 45 degree.
results is:
AW @4A - 1433mAh
TR @4A - 2133mAh

Graph (click for full size)
 
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Re: some 18650 Li-On battery tests 0,5C (Updated 2A constant Load)

Nice to see that your trustfires are working fine :)

Do you also have some 123A's to test? I'd like to see how well they work :)
 
Sorry for the aside here, but what do you use to measure the voltages and graph them? I've already got a constant/selectable current source, I'd just like some way of graphing the voltages of a bunch of cells I've got laying around here.
I've checked online for some schematics (hoping for something cheap and simple), but what I find is a smattering of poorly-written websites, which aren't especially descriptive as to what the available software can do, or how much of a programmer I'd have to be to get it working at all.
Thanks for any help you can give. :)




Update, March 19, 2008: Hi everyone. :wave: I don't know the "bumping" policy here regarding slightly older threads (or thread hijacks like this one:)), so here's an edit.
I got a decent multimeter. MAS345. Serial port hookup, and a pretty simple program that can output CSV files.

I'm surprised that something like that is only $50. I haven't checked out the impedance yet, but it seems good enough. I've been testing out some Li-ion cells I have here, trying to match them up for a new (protected) battery pack. They were salvaged out of a laptop battery.
Discharge rate was 0.5C; time is in seconds. The spikes at the end happened when my discharger (a Triton charger/discharger) hit 3.0V and stopped the operation.

li-ion%20battery%20graph,%20714x356.png

Full-res
Note: I just realized that the "Time" axis is not quite accurate. Each tic on that axis represents 2 seconds.

A few lagged behind, but that 412-2 was really weird, and may be the reason that the pack failed - under high draw, it looks like it (for whatever reason) experiences a severe voltage drop. I'll have to test it again, but I don't think it was a fluke, as the voltage depression took almost 20 seconds to level out into a normal curve. But #353 and #367 were really lagging behind the rest. I don't know why that #503 was so good though; all of these were used together in the same battery pack.

I just charged and retested the #412-2 cell, this time at 1 second intervals (the best the software can do). Same thing - a very brief depression in voltage shortly after the start of the test. 0.379V this time, 0.363V the first time. It makes sense, too. The laptop would run fine if I didn't stress it, but the second I ran a CPU-intensive program, the battery indicator would go from 100% straight to 0% - once it dropped so low, the protection circuitry went nuts and thought the battery had died completely.
 
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Jeff7 said:
Sorry for the aside here, but what do you use to measure the voltages and graph them? I've already got a constant/selectable current source, I'd just like some way of graphing the voltages of a bunch of cells I've got laying around here.
I've checked online for some schematics (hoping for something cheap and simple), but what I find is a smattering of poorly-written websites, which aren't especially descriptive as to what the available software can do, or how much of a programmer I'd have to be to get it working at all.
Thanks for any help you can give. :)
Click to expand...

I am using multimeter atached to the PC via IR to COM. In my case UT60E then all to Exel :)

I do not have LG 18650 or any of R123 size batts :(. I have some unprotected unknown brand, will test them later.
 
Well done :thumbsup: ...

Only one remark ... you should maybe use different colors for the chart lines that are easier to distinguish. Sometimes I had to look very hard which line corresponds to which battery :thinking: and I´m not color-blind ;) ...

I had done some similar testing and found out too that some Trustfires are really good. I used a self-build current sink (the usual design with a shunt, op-amps and some FETs) and a "Watt´s Up, which is handy little thing. It calculates Ah and Wh without the need of a computer doing the logging.

At 2 Amps load some of the Trustfires reached nearly 2500 mAh until the protection circuit kicked in. I said some of the Trustfires ;) ... I do have six in total, two from a order in october 07, four from november 07. The two from the first shipment are the good ones, the four from the second order have only an average capacity of around 2.000 mAh ... which is not to bad for $5 shipped IMHO.

I don´t have any AW 18650 (yet) for comparison, but other Ultrafires, Tenergys and old ones form e-lectronics.net made 2.000 - 2.200 mAh too.

My personal conclusion (too) ... with Trustfire you get mixed quality, some are really good, the rest is average, at least in terms of capacity. Build and long-term quality is the next thing ... looking at your bad Trustfire from the first chart, this could be serious aspect too.
 
I just ran a test with my new Ansmann Xmove battery (dis-)charger/analyzer.

I tested the trustfire 2400mAh 18650. I used a discharge current of 1A, because that's as high as the Xmove will go. It's also a fairly typical current in a lot of 1x18650 lights (maybe 1.5A would have been nicer).

It tested out at 2554mAh, it took 153 minutes to discharge.

I'm impressed, they're the first cells I've tested with my charger that actually meet their claims :)
 
Thanks for going through all of that trouble! The only thing is I'm having a little trouble with some of the first few charts . . . the colors are hard to discern with certainty.

But what I'm gathering from all of this is that the Trustfires beat the AW's? It appears that they certainly did on the 4A test.

What is your conclusion?

:popcorn:
 
I have several Tenergy 18650's (2600 mah) and have been very pleased with them so far but would like to know how they compare to AW's 18650's (2200 mah).

Anyone have both and can answer this question?
 
Huh. I've always supported cheap cells for their bang-for-buck ratio, but even I am impressed. If I'm reading those graphs right (please for the love of God use different colours!), it seems some are consistently outperforming AWs, which is quite a feat in and of itself. They also seem to match with the capacity that's printed on the casing, which is surprising as well considering how Trustfire have never really been honest about that.

I'm quite happy about this test, maybe now we'll get less "All chinese cells are crap" drivel...

How about testing some RCR123/16340s? While I can believe they can stuff enough electrolyte to reach 2500mah in a 18650, I still have serious doubts that any RCR123 can get to the claimed 880mah...
 
My trustfire 880mAh cells manage about 550mAh, so that's something completely different from the 18650 cells. I'm about to order another model of trustfire 880mAh cells, and I have also ordered a pair of AW cells. I'll compare them all, when they've all arrived. I'm curious about their results.
 
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