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Li-ion battery charging help please?

Hi, I have a couple of Li-ion batteries hanging around (one from an old mobile phone and one from an ipod mini), so I was planning to make an LED torch or something out of them. Anyway, can I use an old li-ion battery charger from a camera to charge them without it blowing a hole in my desk? Or whats the best way to charge them? Thanks!

tewharau7 years ago
 If you search for Universal Cell Phone Battery Charger -USB on ebay, you can get a auto polarity checking smart (auto current sensing shut off) Li-Ion charger for just about any 3.6v cell phone or ipod battery.  If you sort on lowest price and shipping, you can get one Buy-it-Now for a couple of dollars (including shipping) or less if you want to wait for an auction to finish.  It has two adjustable prongs that touch the battery terminals and when it senses you have the right contacts, the light comes on, and it's ready to plug in to charge.  Once you have a safe way to charge the batteries, you can concentrate on new things to power with them!
While a little bit of heat is ok, it is vital that you use a charger that is rated for the mAh rating for those packs. If you use a charger that is meant for a more powerful pack, the pack could explode. If the packs your are using are above 1000mAh, I would recommend going to a hobby shop and asking for a lithium ion charger. It would be a little too easy to send a pack higher than that into a runaway state, and possible cause a fire

One last warning: NEVER charge these batteries unattended. If they begin to overheat and you are not there to catch it, the results could be catastrophic
frollard8 years ago
( addon to binary)

a small amount of heat is okay. That third wire coming from the cel phone battery (+ - and T) t = thermistor. It tells the charger what temperature the battery is. Charging will warm the battery a little while the li-ions are absorbing power. When the ions are full, they stop absorbing, and the battery instead gets hot (energy has to go somewhere).
The charger detects the heat, and shuts down until the circuit is broken, then restarts on a new battery.

https://www.instructables.com/id/LED_TORCH_from_discarded_mobile_BATTERY/
110100101108 years ago
if its same volts and close mAH to what the chrger is built for its probably ok if its same volts it may be ok too (you may need to disconnect manually t not overcharge if battery is smaller) if its different volts its not ok anyway see if the battery heats and if yes than you should find other ways to charge it i think those batteries wont explode or do nasty stuff if they dont heat. so i think you can charge hem with just resistor if you keep the current down and dont let it overcharge. i dont know if it has bad effect on the batteries on my experience charging dead phone battery A with phone / gba battery B (by linking them + to + and - to - with 2 wires) heats them up a bit but does not set them on fire either (and i / friends powered up dead phones several times with the help of nintendo). it damages the batteries a bit though