Reference charger for Fuji NP-60 LiIon?

Question

I bought an ultra-cheap digital camcorder the other day for some experiments, and it uses a rechargeable 3.6V, ~1000mAh Li-Ion battery type referred to as "NP-60". I'm not sure if this is actually the battery model, or the model# of the (Fuji) camera for which the battery was originally designed, but I suspect the latter.

Anyway, there is a healthy aftermarket for this particular battery model - it's apparently used in all kinds of el cheapo cameras and such

- and you can buy the batteries retail for as little as $4 for a

1200mAh version. It's small and exceedingly light and would be an interesting choice for some homebrew projects.

However - is there a reference charger circuit for this battery? I haven't been able to find one through Google searches. It seems to be a very simple pack, with only +, - and thermistor terminals. Ideally I'd like a full gas gauge type application, but I'd settle for a simple fast charger.

Luhan · Accepted Answer

Here is the information I used to design my charger...However, I have not yet posted this project to my website...Maybe sometime soon.Luhan

Ted Edwards · Answer

Interesting. That's the same basic technique I used for an uninteruptible computer supply back in the '70s. The computer was powered by a 12V Gates (SLA) battery driving an inverter to provide the various voltages to the computer.

The battery was charged by a line operated 14.7 volt inverter that was current limited. So a low battery was charged at constant current until

14.7 volts then floated at constant voltage.

Ted

Luhan · Answer

LiOn batterys cannot handle a continuous charge.  The charge needs tobe terminated entirely when the charge rate drops to 3 percent ofcurrent first consumed at the float voltage.Luhan

Chris Jones · Answer

I recently read an article about float charging lithiums. They recommended reducing the voltage a little (maybe 4.0) and they noted that the life will be a bit shorter and the capacity a bit lower than for some other usage patterns. They said that as long as the temperature of the battery isn't too high, a quite useful service life can be obtained.

Chris

Reference charger for Fuji NP-60 LiIon?

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