# Bought ANR26650 A123, tobad they are rejects



## steven4601 (Nov 11, 2010)

I bought a few ANR26650 A123's from a suspicious website.

They are real A123's but the the 'A123' name has been lasered through in an attempt to make it un-readable. The bad is the voltage curve. It sags badly under 10A load, they also start to heat up quite noticeably. 

I tried to compare the anr26650 to a Headway 38120 10Ah. 
Both tested at 10ampere constant current discharge. That would be 4.3C for the ANR26650 and 1C for the 38120, but it shows the internal impedance difference better. Headways are sold as 7 ... 8 mili ohms, these are 12 isch or more. What is worse, they the chemicals appear to sag badly. 


Tested 3, pulled one apart, got 96 left 

Bah.


Edit: the 3rd graph is an image overlay of both graphs. It didnt align propperly but shows what is going on. I have numerical data which is more accurate less 'visual' within a forum post.


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## frodus (Apr 12, 2008)

You're doing it wrong....

compare them both at the same C rate, not at the same current. You can't test one cell at 10Ah at the same current as a 2.3Ah cell and expect the same results. 

At 10C the A123 will sag a bit. That actually looks just fine for an A123 M1 cell at 4.3C. If you want to really test it, test A123 at 2.3A and headway at 10A, overlay the results. Then test at 5C (11.5A) and 50A respectively. 

And to calculate IR, you need to measure the voltage at one amperage draw, then quickly switch to another amperage, and measure the voltage. Then use (V1-V2)/(I1-I2) = IR. Not sure how you calculated it, but it sounds like you used one constant discharge to calculate IR, you need 2 different currents that produce 2 different voltages.


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## icec0o1 (Sep 3, 2009)

I don't understand, you want a 26650 to perform at the same level or better than a 38120? Hey, A123 is good manufacturer, but they're not magicians. How'd you measure the internal resistance btw?

Edit: yeah, what frodus said.


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## steven4601 (Nov 11, 2010)

IR was measured swapping between 2.5A, 5A and 10A for good measures. Calculated the results by head though. 

I will do these tests again, not sure why the a123 has been striked through if these are supposed to be good  Cannot imagen it.

Does anyone have discharge graphs at 10A ? I think the cell should drop under 3V after 1900mAh extracted from a full charge, not 1500mAh........


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## frodus (Apr 12, 2008)

Voltage is not an indicator of depth of discharge. They don't drop like lead acid. Lithium remains fairly flat during its discharge. 

The A123 voltage drops below 3V at anything over 5C (11.5A), almost immediately. Take a look at my testing. I did a test with an A123 at 5C constant (not just a resistor) and measured voltage.
http://www.elmoto.net/showthread.ph...battery-test-setup&p=8085&viewfull=1#post8085

If you look at my graph, you can see they're almost the same as yours at 10A. There's nothing wrong with your test, just your expectations.


What is your test setup?


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## alexcrouse (Mar 16, 2009)

Where did u get them? And how much did you pay? I'm.....in the market... *evil smile*


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## steven4601 (Nov 11, 2010)

frodus said:


> Voltage is not an indicator of depth of discharge. They don't drop like lead acid. Lithium remains fairly flat during its discharge.
> 
> The A123 voltage drops below 3V at anything over 5C (11.5A), almost immediately. Take a look at my testing. I did a test with an A123 at 5C constant (not just a resistor) and measured voltage.
> http://www.elmoto.net/showthread.ph...battery-test-setup&p=8085&viewfull=1#post8085
> ...


Im recharging that same battery now again, going to run the test at 2.3Ah.. 

I'm using a RC plane charger/discharger. iCharger 3010. It goes upto 30A charge or regenerative discharge as long the power is less or equal to 1kw. A 12V lead acid battery is being used to dump the discharge energy into. 




*charge is ready now, going to let it settle for 20 minutes then start the 1C discharge.


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## frodus (Apr 12, 2008)

do a charge at 11.5A (5C) and compare it to my discharge curve. I don't have a 1C diacharge curve handy right now.

Best to compare 2 of the same discharge rates and look at them.


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## steven4601 (Nov 11, 2010)

np, will do 11.5A too, that doesn't take that long anyway 

Edit can you post the graphs you made on this forum? I do not have an account for the website you linked to which prevents me from viewing the uploaded content. 
Also what was the cut off voltage at 11.5A


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## frodus (Apr 12, 2008)

get the cutoff voltage from the A123 M1 datasheet, its 2V.

Here's my curve.


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## steven4601 (Nov 11, 2010)

Travis, Do you have a better image of your graph? I find it difficult to see the voltages @ mili-amp-hours. 


here is what I have managed to extract from the cvs tables.
2.3, 10 and 11.5A discharge plots CC mode.


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## steven4601 (Nov 11, 2010)

This graph is not 100% accurate as I had to try to match the two different scales which is not exact due to the different voltage cut-offs, run times etc.

It maybe not as bad as I thought.
1C Headway 38120 10Ah vs 'rejected' 1C ANR26650m1A


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## frodus (Apr 12, 2008)

not here, its at home, and I'll probably forget to post it. What I'm telling you, is that your discharge curves are normal. If you want more curves, look up A123 discharge on google, there's plenty of them.


volts is in green, temperature is in red, seconds is on the bottom, so its not in Ah on the bottom.

Just compare the look of the curve. The bulk of the discharge is at 3V or lower.


BTW, The time is 16sec/div and the volts is 0.108V/Div. So you just need to count the divisions.


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## frodus (Apr 12, 2008)

steven4601 said:


> This graph is not 100% accurate as I had to try to match the two different scales which is not exact due to the different voltage cut-offs, run times etc.
> 
> It maybe not as bad as I thought.
> 1C Headway 38120 10Ah vs 'rejected' 1C ANR26650m1A


Now do that at 5C and compare the two. From what I found, they're fairly similar, and the headway lasts longer but heats up more.


Good tests BTW


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## steven4601 (Nov 11, 2010)

5C & Headway 10ah cells, I dont have a 50A CC load.
I can try 2C.


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## frodus (Apr 12, 2008)

I guess my point is, your "A123's" are fine, just not what you were expecting (I'm not sure what you were expecting though)

test as much as you want, but they exhibit the normal curves of a lifepo4 cell.


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