Lithium battery charger

Hi!

I'm working on formula student project and we got this 4 batteries from our sponsor:
**broken link removed**

And we are planing to use them instead of regular lead battery, but we need to build dedicated charger to charge this batteries because we can't connect them directly to the regulator output.

I've looked on internet and there are few examples how to build such kind of charger for the 3.1 V battery, but we are having 4 x3.3 V batteries connected in series so that is equal to the 13.2 V, and I didn't found nothing for this.

Does anyone know simple but reliable way to realize such kind of charger?

Thanks!

Thanks on answer!

So do you know some good schematics for charging this cells, which will automaticly stop the charging when the voltage rises to 3.7.

Also can you tell me, should I use some thermal protection because in datasheet says that it have one inside!

You can charge them in pack in serie with balanced charger. No need to charge them separately. Always is better to charge each cell separately but this is often impossible for examples car batteries, laptop, hand tools batteries, ....

;-)

Integer said:

Thanks on answer!

So do you know some good schematics for charging this cells, which will automaticly stop the charging when the voltage rises to 3.7.

Also can you tell me, should I use some thermal protection because in datasheet says that it have one inside!

Click to expand...

Just search for a adjustable voltage regulator schematic capable of supplying enough current to feed all the paralleled cells. I suspect that 1 to 5 Amperes per cell will be fine.

If you set the voltage to 3.7 V and glue the setting on the charger so it won't change; will not need to turn off the charger, it will stop itself from delivering more charge to the cells when the voltage is reached.

Check that temperature stays under 55C and it will be all fine.

Sorry, deleted one duplicate post of the first response and both dissapeared !

A123 Systems had trouble with their batteries that were recalled then auto manufacturers refused to use them so they went bankrupt.
A Chinese company wanted to buy them but Pres. Obama said NO WAY since the US government put a lot of money into A123 Systems

So good luck with your batteries that might fail and will not be able to be replaced.

Externet said:

Just search for a adjustable voltage regulator schematic capable of supplying enough current to feed all the paralleled cells. I suspect that 1 to 5 Amperes per cell will be fine.

If you set the voltage to 3.7 V and glue the setting on the charger so it won't change; will not need to turn off the charger, it will stop itself from delivering more charge to the cells when the voltage is reached.

Check that temperature stays under 55C and it will be all fine.

Sorry, deleted one duplicate post of the first response and both dissapeared !

Click to expand...

I not suggest paralleling Li-Ion batteries, and charging process should be done with controlled circuit designed for this type of batteries. That circuit should comply Li-Ion Prismatic batteries requirements for terminating charging process, voltage control during charging, temp control, current control,...

:wink:



Interesting link for electric car batteries:
https://twinkle_toes_engineering.home.comcast.net/~twinkle_toes_engineering/hybrid_car.htm