
30th Jan 2007, 5:23 am
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New Member
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Join Date: Jan 2007
Posts: 4
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Quote:
Originally Posted by mpj-mlj";p="
Don't be too mad at your brother.
It was most likely a failure of the internal charge circuit or just a bad battery.
Lithium polymer batteries are charged at a precise rate - determined by the internal charger.
A properly designed LiPo charger will NOT let the battery go above 4.2 volts. If I recall correctly, damage occurs just over 4.23 volts.
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Besides the hacked memory reporting, this is another area of concern for these MPx players. I had to repair a friends nano-clone a few days back (cracked resistor on PCB) and I was pretty shocked to see the LIPO charging circuit, just a silicon diode to drop the USB voltage by 0.6-0.7 volts and a 1.5 Ohm resistor to limit current...that was it! Like you I fly RC models and know how dangerous LIPO's can be, and how critical the charging termination voltage is.
A further problem is that many chinese LIPO's are of poor quality anyway, and are more prone to damage, even if charged correctly. The combination of crappy cells and non-existant voltage control in the charging circuit makes me very surprised that their aren't more posts about this. Perhaps some of the other players have better chargers, I can only hope.
I bought one of the "Glacier" style players through Ebay, sold as a 4GB but I bought it hoping it would be a 2GB and things have turned out ok. The beauty of these players is that the LIPO is the same as used in some Nokia phones, so is easily removable. I'm going to get a desktop charger for mine rather than relying on built in circuit.
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