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Jan 29, 2013, 02:38 PM
AMA Life Member 'Ezflyr'
Discussion

Capacity Testing XPS


Hi All,

I have a pair of 2S, 2300 mAH A123 packs I purchased from XPS about a year ago. At the time I fully charged them with a Thunder Power balancing charger. I'm about to use these packs now, so I'd like to capacity check them first. When I attempt this, I end up with a ridiculously low capacity of 75 mAH or something like that. When I recharge the packs, that is approximately the same amount being put back in. I assume I'm not discharging them properly, and probably ending prematurely. What is the per cell cutoff voltage that is appropriate to these A123 batteries?

Anything else I might be missing?

Thanks,

John
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Jan 29, 2013, 03:15 PM
Registered User
E_ferret's Avatar
Quote:
Originally Posted by ezflyr
Hi All,

I have a pair of 2S, 2300 mAH A123 packs I purchased from XPS about a year ago. At the time I fully charged them with a Thunder Power balancing charger. I'm about to use these packs now, so I'd like to capacity check them first. When I attempt this, I end up with a ridiculously low capacity of 75 mAH or something like that. When I recharge the packs, that is approximately the same amount being put back in. I assume I'm not discharging them properly, and probably ending prematurely. What is the per cell cutoff voltage that is appropriate to these A123 batteries?

Anything else I might be missing?

Thanks,

John
You can use your computer for more than communicating with Jim!
required information is only one click away;
http://www.a123systems.com/Collatera...ta%20Sheet.pdf
Jan 29, 2013, 06:35 PM
Registered User
crazy8s's Avatar
Quote:
Originally Posted by ezflyr
Hi All,

I have a pair of 2S, 2300 mAH A123 packs I purchased from XPS about a year ago. At the time I fully charged them with a Thunder Power balancing charger. I'm about to use these packs now, so I'd like to capacity check them first. When I attempt this, I end up with a ridiculously low capacity of 75 mAH or something like that. When I recharge the packs, that is approximately the same amount being put back in. I assume I'm not discharging them properly, and probably ending prematurely. What is the per cell cutoff voltage that is appropriate to these A123 batteries?

Anything else I might be missing?

Thanks,

John
I apologize in advance if this sounds insulting (not meant to be) but you ARE using a charger that has a LiFE setting on it, right??
Jan 29, 2013, 10:13 PM
AMA Life Member 'Ezflyr'
Quote:
Originally Posted by crazy8s
I apologize in advance if this sounds insulting (not meant to be) but you ARE using a charger that has a LiFE setting on it, right??
Hi,

Yes, the Thunder Piwer TP-610C does have a LiFe setting! The default cell discharge voltage is 3.3V, so I was seeing virtually no capacity after a full charge. Once I saw the discharge curves, I realized I could set the cut-off to 2V, and now I'm measuring rated capacity!

Thanks!

John
Jan 30, 2013, 01:32 AM
Registered User
Doffen24's Avatar
Quote:
Originally Posted by ezflyr
Hi,

Yes, the Thunder Piwer TP-610C does have a LiFe setting! The default cell discharge voltage is 3.3V, so I was seeing virtually no capacity after a full charge. Once I saw the discharge curves, I realized I could set the cut-off to 2V, and now I'm measuring rated capacity!

Thanks!

John
Do not go as low as 2V. Minimum Voltage should be 2,5V. Almost no difference in capacity between 2,5 and 2,0 volts due to steep discharge curve. Your batteries will last longer though....
(said that, a couple of my A123 cells where discharge completely -due to forgot turning off-, and I got it back to ŽlifeŽ again after a couple of cycles . They never seem to stop surprising me)
Last edited by Doffen24; Jan 30, 2013 at 01:35 AM. Reason: trying to get it in Engliscsh...
Jan 30, 2013, 09:05 AM
Xtreme Power Systems
3.3v is the normal operating voltage. A123 cells will retain their voltage for a very long time and then suddenly they will rapidly drop all of the way to zero. Cut-off at 2.5v and that will give you your capacity.
Jan 31, 2013, 07:36 AM
AMA Life Member 'Ezflyr'
Hi All,

Actually, I misspoke. The minimum cut-off voltage on the Thunder Power Charger I'm using in LiFe mode is 2.5V per cell. At that setting, I am getting rated capacity from my XPS A123 packs!

A special thanks to E_ferret for pointing out all the new-fangled things I can do with these computers !

John
Jan 31, 2013, 03:26 PM
Registered User
E_ferret's Avatar
Quote:
Originally Posted by ezflyr
Hi All,

Actually, I misspoke. The minimum cut-off voltage on the Thunder Power Charger I'm using in LiFe mode is 2.5V per cell. At that setting, I am getting rated capacity from my XPS A123 packs!

A special thanks to E_ferret for pointing out all the new-fangled things I can do with these computers !

John
You are welcome! If you need further help, I cut my teeth (so to speak) on IBM 407s, so if you need help with point-to-point wiring, I'm the man.


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