Reference: mitro's pile of battery graphs

Batteries and Chargers Rechargeable Batteries
21

I've added the ability to monitor the amperage with my DMM inline with the tester. So I can verify the current draw of the CBA along with the cell voltage (which I'd already been doing). The bad news is that it threw my calibrations all off. So now I have to do partial tests to dial in the voltage correction factor AND the amperage correction factor. Even without calibrating the amperage, it looks like my results are AT WORST accurate within 5%. This should knock it down below 2% for a worst case scenario. Not really sure its worth it now, but I can't easily go back.

Long story short... I had what I thought was a good idea but its going to take even more time and a second DMM to not gain much over my previous setup. This is nothing new nor suprising for me and my endeavors. :)

22

Mitro, so you are saying that your tests are all accurate to within 5% at worst?

I'd already be very happy it they were 10% worst case. I have 3 pairs of generic IMRs coming my way that didn't cost much (18350, 18500 and 14500s), thank you very much for the nice info! Sealed

23

My measurements are within 5% of being accurate. There’s still other factors to consider. Number one being variations in charging (which I do my best to minimize, but are impossible to eliminate.

I'd bet my house that I can get the Ah and Wh within 10%. Typically on a 0.5A I could be off 10 or 15 mA per hour of testing. That's 50-75maH on a 2500maH cell so 2-3%. Shorter tests have less error. My worst test is a 5A, at a possible 50mA per hour of testing (its actually more accurate at only 1% of the discharge current), but it would take a mighty large cell to make that significant since most 5A tests last a fraction of an hour.

It looks like I took a step backwards with my new hook up. Where I used to be able to plug in a pre-tested correction factor for voltage at a given amperage, I have to calibrate every single cell I test at every amperage I plan on testing. I think I'll be going back to the old way. Adding the DMM in line just added uncertainty and more connections.

EDIT: I may have to get a pair of those 18500s for some shorty Skyray action.

24

I'm actually to the point where I think too much import is put in the cells we are using. Here's an interesting (or at least I think so) comparison.

This is part of a graph of a constant 3A discharge. Its also using watt-hours instead of amp-hours. The Trustfire (flame - bought from Manafont) puts out 88% of the power of the Panasonic based 3100 when going down to 3.0v. At 3.25 only the Sanyo is out ahead of the pack.

From what I've tested the NANJG 8x7135 driver ACTUALLY cut out above 3V. I'm not sure if its the resistance of the host or what, but I can't get LiFePO4 cells to run on this driver on high at all. These cells have VERY little voltage sag so I know its certainly above 3.0v battery voltage.

A little bit of a tangent, but I just have observed that specifically with the 8x7135 drivers you are wasting a lot of capacity.

Now in the dressed up direct drive lights like the 980L, I think these higher capacity/lower voltage cells are a better choice.

25

Hi mitro, I hope you dont mind i borrow your graphs from time to time as comparisons when i post a test i did with my cells. I ALWAYS say its your graph and work that made it and give you credit. I figured as long as i did that you wouldn't mind. But if you do mind pls tell me and ill stop.

I know its to late now, But can you start doing graphs that include "Time" as a factor so i can see when 3.3v is reach at say 30 minutes? I like graphs like that for lights that shut off at 3v and also i always stop my tests at 3v as i dont see any real world use to test a cell down too 2.5v like many people do to try and say a cell does reach its "Stated" capacity.

If it cant do it at 3v its shouldn't be counted below that. Now i see you do sometimes use 2.8v and 2.5v and thats your choice, But i guess if its a single cell light with direct drive it could have some extra run time giving it some meaning. Thats just my opinion and is no big deal as the real reason is of including the "Time" axis is.

BTW thats for all your hard work and stress on your cells also, I use a Hyperion 720i which is so easy to use. But its a time consuming job since you dont want to walk away from cells being discharged at 5A and try and do something outside. So a Thank you for your work from someone who knows how much it takes to do all this. Let alone the expense.

26

I have no problem with you using the graphs! That's what there for. :)

I CAN do graphs with voltage over time and I'd be happy to do one if there's a specific one you'd like to see, but to do it for every test would add quite a bit of work.

You can get a pretty good idea just by looking at the graphs for amp hours. Just look at the approximate amp hours at the target voltage and divide by the test amps (and multiply by 60 if you want minutes).

OR you can just ask me and I can look it up in the data.

27

If there is a specific one id like to see ill ask, Thanks.

Math makes my head hurt :)

28

Callie's Kustoms High Discharge 18650 #1 (rated 2250mAh - Panasonic CGR18650CH)

Number of cells: 1

Cell Graph:

Capacities discharged to 3.0v:

  • 0.5A: 2310 mAh
  • 1.5A: 2182 mAh
  • 3.0A: 2192 mAh
  • 5.0A: 2095 mAh
  • 10A: 1862 mAh

MF UF test:

4.652 Amps

The max current drawn from the cell using the Manafont Ultrafire T6 P60 drop-in in a L2p host.

Low voltage cut-off

N/A

Callie's Kustoms High discharge 18650 vs. others

3A:

  • AW IMR
  • Bestinone.net
  • Sanyo 2600
  • Callie's Kustoms 3100
  • Trustfire Flames 2400
  • Callie's Kustoms HD 2250

Comments:

This is one heck of a cell. You aren't going to come close to its capacity in any other IMR 18650. It destroys the AWs I have and the Bestinone.net cells I tested. It doesn't quite have the capacity of today's LiCo cells, but it holds voltage higher than just about all of them. The only competition are the Sanyo 2600s I have and there's nothing intrinsically safe about them.

They do get plenty hot during a 10A discharge, so I wouldn't use them at that rate, but so do my AWs (Which I actually haven't completed a full discharge @ 10A due to them getting so hot)

The 4.6A draw I got from the MF/UF test is the highest I've ever seen, it even beats an IMR 26650.

29

Thanks for testing them! I knew they where good but wow! How do you think they feel about them over at CPF?

30

I’m not sure, but I can’t come up with a reason to buy AWs over these. The AWs i have are now almost 2 years old, but even when they were new they didn’t live up to what I expected from them (neither did the 16340 or 26500 IMR for that matter). These Panasonics are in a whole 'nother league, so I don’t think it should take much convincing over there. They like to spend money. :slight_smile:

I'm going to charge and discharge this one like I would any other IMR and see how it is after some use (and likely abuse).

31

Some buddies here recommended Mitro to be a condidate to review our new updated WP2 charger, and I have sent a message and waiting for confirmation, can I have the honor?

Miles

32

I didn't see your post until now, Miles. But we've already talked in PMs, so its all good. :)

33

Here is a Callie's Kustoms HD 18650 vs. my 1+ year old AW IMRs. I actually thought they were older than that. Is this a fair comparison? You decide.

I keep reading words like "reliability", "durability" and "long-term" when talking about reasons to buy AWs. So it stands to reason that the AW should be able to hold is own after a year or so. These 9 runs were all done TODAY (8/23/11).

The Cells

AW IMR 18650 #1 & #2

Purchased: From Lighthound 6/18/2010

Usage: Not much. Occasionally would fill in for a LiCo in a 1.4A light and rarely run a ROP Hi. Most of the time they have been stored. Some of that time was fully charged just sitting on the shelf and the rest of the time was stored @ 3.8v in the fridge.The cells have never sat after being discharged and I followed charging guidelines specified by AW, but almost always charged them at or above 1C.

Callie's Kustoms High-Discharge 18650 #1

Purchased: Was given to test by Jordon @ CK - 8/8/2011

Usage: Limited testing. Now I'm starting to use them the way I would any IMR (discharging to 2.5v and charging at 1C+)

Facing off at 3 Amps discharged to 2.5v:

AW IMR #1: 1272 mAh
AW IMR #2: 1338 mAh
CK HD #1: 2227 mAh (2180 mAh to 3.0v)
(I forgot to put the temp sensor on until the very end)

OK.... how about 5 Amps (to 2.5v):

AW IMR #1: 1219 mAh
AW IMR #2: 1294 mAh
CK HD #1: 2201 mAh (2127 mAh to 3.0v)

Time to put it all on the line - 10 Amps! (to 2.5v)

AW IMR #1: 81 mAh
AW IMR #2: 103 mAh
CK HD #1: 2209 mAh (1967 mAh to 3.0v)

I'd call that a K.O.

If anybody would like to test my cells to verify my results, I'd be happy to send them to you, just please don't return the AWs. :) Likewise, I'd love to test some new AW IMR18650s if anybody wanted to loan them to me. (Unless you are AW, in which case I'm keeping them for repayment of all the underperforming IMRs I've spent hundreds of dollars on.)

Maybe a new pair would hold their voltage better than the CK, but I think that would be tough. There's no guarantee that they are even the same cells underneath. (I know what a CK HD is. :p) Even then, they're going to lose in the capacity department by a wide margin.

The only other areas of concern are longevity and safety. My pair of AWs may last forever and not lose any any more capacity, but they don't have enough to begin with. The main concern with the Panasonics is the "unknown" level of safety. Until somebody shows me what it takes to make both cells explode, and that there is a difference, I'm going to treat both the same.

34

Yikes! Honestly I'm pretty surprised. I would think the AW's would have the clear advantage at high discharge rates. Honestly I cant help but think the AW cell is damaged to do that poorly at 10A ??

"The main concern with the Panasonics is the "unknown" level of safety. Until somebody shows me what it takes to make both cells explode, and that there is a difference, I'm going to treat both the same."

I'm completely on board with you on this! In fact we are going to be changing some wording on our website so people really understand no battery is safe. I mean really... when I was a child I had it pounded into me about battery not being safe. I think its better to error on the side of safety rather than catch your self on fire or get burnt up with acid.


35

I agree, but these cells have never been abused. No dead shorts, no overdischarges. no resting after depleted, and the only times they were depleted was for tests. Also, they readily charge to 4.2v and hold their charge. They also has a relatively normal curve under a decent load (5A).

My only guess could be that regularly charging the cells at higher rates (2C), while within specs according to AW, result in degradation. However, I looked at a graph from a test I did 10 months ago and the curve (another 5A graph) was nearly identical to the ones done today.

BTW, the Panasonic is GAINING capacity. :) 2200 mAh @ 10A is unbelievable.

36

Very nice mitro , though the demand for a 10A test , I think was a bit of a [ hmmmmm ] unreasonable demand , and I thought it insanely funny when posted on CPF ...

But the fact that the two IMR;s fell on there face and the Panasonic performed well , kind of speaks volumes ...

Now when I see the Enemy post [ yes I think enemy ] , a AW review , must remember to demand a 10A discharge ...

But the whole thread unfortunately deteriorated , with some very silly [ Stupid !!! - who am i kidding ] comments and demands ...

Thanks mitro ...

37

Think you forgot to charge the AWs for 10A.

38

Thanks for tests mitro, very interesting - very entertaining! :)

Ok, AW´s are old BUT I think you have kept them in better shape than a big deal of users would ever keep.

They seem to perform well on two lower current tests but omg with that last one...

I would have bet my money EVEN on 1yr old AW´s, seriously I´ve had the image of better performance on ridiculous amps...

Panasonic is really gearing up in battery race. Do I remember correctly Panasonic owning Sanyo?

So, they have the NiMh covered pretty damn good I´d say, with Eneloops. Now this. Whew... :o

39

Thank you... and thanks for all the testing you've done.

I did the 10A discharge on the cell because Panasonic says it can. I had already done it once for my initial tests, but its gotten stronger since then. I'm not here to sell CK cells. Jordon was nice enough to give me one to test and if the results were poor, they'd be in the above graphs. I like cells that perform up to, or beyond, expectations. I think we all do. :)

40

LOL It looks like that, but I assure you, they were charged to 4.2v.

EDIT: I think I may need to do a 7 or 8 amp discharge to fill in the gap to see where it goes south.