Li-Ion battery charging - Waking sleeping batteries

Thread Starter

atanumukerji

Joined Apr 1, 2011
21
Dear all,

I have designed a system which uses a 7.4 V, 6,6AH Li-Ion battery pack (18650) in the configuration 2S-3P. It is charged using a uC based software algorithm which is CC till 8.4V and then CV till current falls below 0.05C. I charge the battery using a 12V DC charger or a 15W, 12 V Solar Panel. Obviously there is a buck-converter in between which manages the voltage applied to the battery.

Recently I came across situations that batteries which go to sleep would not revive using the software charger. I had an earlier version of the same system using a different microcontroller SH4 from Freescale, which would wake up the battery. However the new version uses a different microcontroller MC9S08PA4VWJ which does not work. The only change is I see is the speed of operation - it was 12KHz for the buck converter PWM earlier and now it is around 35KHz.

Can any one suggest what is wrong or what I should try? Please ask if you need more information.

Thanks in advance
 

burger2227

Joined Feb 3, 2014
194
Lithium battery packs require protection circuits to monitor each series battery connection. Parallel series connections can all be monitored with the same board. The protection circuit can also be used in the device to protect batteries from excess discharge, overloading or overheating.

You can get the boards on Ebay.
 

Thread Starter

atanumukerji

Joined Apr 1, 2011
21
Thanks. I will try to cull out the circuit subsection and post it.

As for the PCM card, it is already there on the battery pack I am using.
 
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