Chemistry Selection for an unknown Cell

Hello,

We can help identify the chemistry, but the logfile needs to be in the form described in application note SLUA544 (How to Generate Golden Image for Single-Cell Impedance Track TM Devices)

Fundamentally, you need the following:

1) a charged, relaxed battery

2) C/10 Discharge to the terminate voltage

3) 5 hours of relaxation at this low state of charge

Your discharge looked like this:

(mV vs. Sample)

Note that the battery IS relaxed properly, but the discharge rate is too fast (150mA, as you mentioned above, is roughly C/5 for an 880mAh battery)

Also, you never terminate your discharge, and the battery voltage crashes to basically zero.  You need to turn your system off when you reach end of discharge and let the battery relax.  The voltage curve will look more like this:

Let me know if this helps,

Charles

Thanks for ur valuable reply.

I did as u said by having discharge current approximately C/10 (ie. 50 mA). But the above said Li-ion battery cuts off (RSOC becomes standstill) at 3V itself. So i cudnt do the relaxation of battery for 5 hours. Also in middle of the process how can i relax the battery for 5 hours manually other than disconnecting the load ? Wont it select inaccurate chemistry? I have attached the log sheet in compressed format (RAR). I know it is half done. Is this log sufficient to select the chemistry ? If possible  can u select or tell me the chemistry of the battery used?

0435.Discharging Cycle for 50mA_05_01.rar

Awaiting ur reply. Thanks once again.

Kasthuri,

Unfortunately, we really need the second relaxation point at low state of charge.  This gives us two OCV points on the battery with which we calibrate everything else. 

Basically, you will need to remove the load entirely when the voltage hits ~3V.  Because of the length of this discharge, it pretty much has to be automated.  Is there any way that you can set up a cycle to do this?

Thanks,

Charles

Hello,

I think to have understand the correct way to perform the Chem Id Learning Cycle for non rechargeable batteries.

I've only one open point: wich is the "terminate voltage"? Is this the minimum voltage at which my electronic (fed by the battery) stop to work?

Charles, can you help me?

Thank you very much,

Davide Gavioli

EGICON Srl