You should definitely NOT mess around with lithium based batteries, they can and will EXPLODE or CATCH FIRE if charged with too high of a voltage or for too long. Look at videos on Youtube if you don't believe me.

I often need to charge those separately from the devices they came from, but became worried when some of the older ones started to swell up, and after reading about the fire hazard when using improper methods for charging lithium batteries, i built myself a Li-ion charger circuit. ;) That way i can still recharge any type of Li-Ion or Li-Po battery and recover old batteries that have been disabled by the safety circuit for getting too discharged while still being sure they aren't going to blow. If you do charge them, charge them the right way.

And the new one......

Works to perfection, YAY!!!

However i now think that the first one(with the bust battery) was second hand, becouse the new one is supposed to be the same but the firmware is different - different welcome and goodbye screen, more animations ect.

Great to know you got a good replacement. :)

Hey, could you post a circuit diagram of the charger you built? I would like to do the same.

-freddy

Re: Help with Mp4 player battery
 

Maybe because my battery isn't Chinese,
I don't know where it was manufactured.
However, even after these start-stop cycles,
the battery is really weak, and can stay for 2-3 hours at max.

Re: [solved] My Battery has expanded!!
 

WOW, did you see your player expand while on your lap for 5 minutes?!! Phew, consider yourself lucky you didn't damage 'anything' else!

Glad you got the player replaced and with a better model one. Where did you buy it from by the way?

Also, what did the seller say about it and whether he gave an explanation to the problem?