Charging old phone batteries

I have a nokia Bp5m battery. i want to use it for my project, but i don't know how to charge them. they have 3 terminals, and i don't know how to wire it up. anyone has any experience in this? i want to charge them without placing them in the phone, want to charge them directly from the charger

If it's a lithium battery, it probably has protection circuitry in it and one of the terinals is used by the charger to enable it.

Yes it is a lithium battery. still not sure how to wire it up though

BioniC187 said:

Yes it is a lithium battery. still not sure how to wire it up though

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I would not recommend it. Use the correct charger.

this battery is out of my old nokia 6110 navigator. i have teh original charger for the phone also, so i want to wire both up

The correct charger circuit for a lithium phone battery is INSIDE THE PHONE!
People who know nothing about electronics call the 5V power supply a charger but IT IS NOT A CHARGER, it simply powers the charger circuit that is inside the phone.

If a lithium battery is charged wrong then it can easily catch on fire.

there are standalone chargers available in market. they have adjustable connector with clip like mechanism and the charge controller in built. otherwise you can use the phone itself to charge the battery now and then.

Yes, as Audioguru rightly pointed, any mistake would blast the battery on either your or some else's face.

BioniC187 said:

I have a nokia Bp5m battery. i want to use it for my project, but i don't know how to charge them. they have 3 terminals, and i don't know how to wire it up. anyone has any experience in this? i want to charge them without placing them in the phone, want to charge them directly from the charger

Click to expand...

Be careful. The third wire (often white in colour) is a thermistor commoned to ground. It's used by the charger circuit to prevent charging at extreme temperatures. Normally it can be ignored, but if you try to charge the battery below 0deg C, it can explode.

You need a dedicated Li-Ion charger circuit. The LTM8061 range from Linear Tech can do this easily.

The charger (as previously posted) is a power supply. The phone itself does the charging regime which is far more complicated than simply putting a battery across a power supply.

You need to charge at constant current to 4.2V then constant voltage until the current drops below a threshold determined by the capacity of the battery - usually C / 10 where C is the capacity of the battery. Linear Tech Chips sort all this out for you.