Jeansy's battery tests (new impedance tests)

Batteries and Chargers Rechargeable Batteries
1

Hi everyone,

I am discharging a few cells to see how they preform and thought some of you guys might be interested. Im sure there are better was to test but this is how i have quickly set it up. My Fluke meters are calibrated by an external company (Pullman instruments), these give a accurate idea whats actually being drawn from the cell.

Ok just to explain what the pictures show. The Fluke 179 on the right is wired in series with the cell and charger, so what ever current goes through the cell goes through the meter, this shows that the hobby charger is actually discharging at the correct rate as they are far from accurate in some cases.

The Fluke 123 on the left is displaying the voltage across the cell, this again shows how accurate or not the charger is. In this case it shows that infact the cells are being terminated early so the capacity reading will be lower than could be expected should you discharge further, ie 2.7volts.

If the two figures are multiplied then the result is the power consumed, eg 3.8v X 1a = 3.8watts.

The other variable for my charger will be the timer itself so perhaps I will stick a stop-watch next to the counter and ensure that is accurate. Edit:Tested to within 2seconds at 2hours.

[Added 1-5-12]

Please only compare my results within themselves, my methods mean that lower readings will be obtained compared to other people's. Within themselves these results should be very accurate and representable of performance.

Little table with Impedance readings and some random calculations i was interested to compare:

Why Impedance is important: The output capability is determined by the Impedance if nothing else limits the cell, ie in a direct drive light, lower impedance = more current and more output (or a blown emitter). Impedance also steadily increases with age and gives a good ability to trend and thus monitor ageing. Impedance matching is also more useful than voltage matching cells for multi-cell set-ups, it tends to give far more accurate results, tho DC matching is still essential.

Edit:

So far:

King Kong 26650 - 4031

Panasonic NCR18650A 3100mAh - 2609>2619

Sanyo 2600 - 2256>2339

SenyBor SYB18700 2600mAh - 2219

SoShine 2800mAh - 2095

TrustFire Flame 2400mAh - 1817

UltraFire 'blue' 2400mAh - 913

Trustfire flame 14500 900mAh - 640 (1a)

TrustFire tr 10440 600mAh - 243 (0.5a discharge)

Ultrafire (silver) 14500 900mAh - 124 (1a)

Anyway, SenyBor first:

Please comment if these are usful and i will add some more as i do them (Trustfire Flame discharging at present)

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Panasonic 3100, first cycle (as other cells), sourced from HKE. Not a great result but as you will notice the charger is terminating early, still interesting to directly compare with my other results....

4

SoShine 2800mAh

5

So your charger is reading ~0.3v low? You are really only discharging down to 3.3v then. Looking at my discharge of a 3100 it looks like your numbers are right for discharging to 3.3v (even though this is 1.5A):

6

Yes terminating around 3.3v, bit annoying but i dont really want to take them lower than 3.0 anyway so reluctant to use the NiMH discharge setting. My UltraFire 'Blue' 2400mAh did less than 1000mAh lol, maybe it could of got there down to 2.5v!

7

Very interesting. Thanks, Jeansy. :)

Please keep them coming.

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If your B6 is consistently reading 0.3 volts high, just set the NiMH discharge termination voltage to 2.7 volts....

Mine reads dead-on compared to my DMM at the jacks, but has 0.1 ohms in the alligator-clip cable and thus reads 0.1 volt low compared to the battery itself on a 1A discharge. So to terminate at 3.0 volts, I use the NiMH program set to 2.9 volt termination.

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Cheers Ralf, will look into that although I want to directly compare cells so will have to keep an eye for the 3.cut point or re-test the above.

Anybody have any requests, could do with a couple more so will be ordering soon

10

Well... I know I am not being creative but since you have calibrated equipment and most of us aren't fortunate enough... ;) TF Flame 14500s and 16340s, perhaps? Personally, I'd also be interested in seeing how various 10440s perform side-by-side. But I do realize that 10440s aren't particularly popular. Also, could you please add where you got your samples from? Thanks again.

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Panasonics, HKE

Soshine & TF Flames, DX

Senybor, Scottish EBay seller

I have some 10440s on route (DX silver TF) for my Olight but couldn't find many, any links? At present I have no use for the other sizes but maybe some 14500s soon

12

Very nice Jeansy! Thanks for your hard work and the great details.

Sticky'd.

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Excellent test, i like how you discharge to 3.3v if i understand correctly. This gives us single cell users a more realistic although lower figure. As the only way the discharge to 2.5v or even 3v is a multicell light or some fancy electronics. Some cells hold a higher voltage over the usefull part of the discharge cycle in a single cell light which translates to longer run times, although they might not show a higher capacity if taken down to 2.5v, it doesnt matter as the light will be putting out as much light as a glow worm by then anyway… +1 for the 14500/10440. I saw some 5000mah 18650’s on ebay it would be fun to test one of those, i find it frustrating that sellers can rip people off so openly. Oh well thank goodness for people testing and enlightening us.

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Top post updated with trust fire 10440(silver) & 14500, both from Manafont, charged on delivery and first discharge, will update more when I have some time.

Unless indicated everything is at 1a discharge.

15

nice photos!! (i dont really understand why i am seeing there.. but they should be helpful once i get my first hobby charger)

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Hi JEansy, did not see your thread. Interesting!

Yeah, i have the genuine IMAX B6 too. I see it to 2.6V termination. Just measured 2.82V termination on the DMM (UT-58E). So pretty high. ~ 0.2V difference.

Though low, it is definitely realistic and won't harm the cells, well not to the extent that we are using our lights and cells (we have way too many cells). Some drivers' LV protection do terminate at such levels, looking at the end open-circuit cell voltage after letting the cells rest. The PCB also does not cut in that early or with low amps.

For my pro photography - i have like 10 packs and whack the hell out of them sometimes (eg over the weekend i took nearly 8k frames over 4.5 full-day weddings relatively speaking, it was 20-11-2011 and 2 weeks ago it was 11-11-11...heh), i still have batteries that run pretty "ok" though i can feel that they have aged and don't hold a charge too well. But they have been with me for > 5 years!

Flashaholics with 20-30 18650s will never feel any "degradation" from over-discharging to 2.8V esp if you mix the cells around across your whole collection. Unless you use them daily 1 or 2 full cycles per day and tag a few to certain lights that you use often....then probably it could happen maybe in 2 or 3 years.

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Ok, i quickly had access to our Hioki battery tester. This is a calibrated, dedicated battery tester, as you can see below it measures the DC voltage but much more interestingly the internal impedance. The tester is a great indicator of battery condition if results are trended. Low readings are better and give an indication of outright power avalible.

The tester doesnt look overly impressive but it retails in England at approx £1500 or approx $2000USD!

I will try and write up the complete results soon, at least two of all the cells were tested (bar the King Kong)

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Which cell is the last one(pink)?

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Values seem too low for me.

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Sanyo cell is the pink ored from intl-outdoor.

Viffer, this is calibrated and used commercially. It is endorsed by Yuasa also. I would suggest other readings you have seen are high ;)