Li-Ion battery question

I remember a guideline saying that the voltage has to be accurate to 50mV. You just have to find the correct voltage for a given cell model from the cell manufacturer; the consequence of a bad choice might be a battery explosion. Someone in the newsgroup claimed that they tested their Li-ion chargers/batteries under a blast shield.

Most of the time the choice of 4.1V or 4.2V charging voltage depends mainly on the life requirements you require out of the Li-Ion battery, lower equals longer life but lower capacity. This voltage represents the max limit when transitioning from constant current charging mode to constant voltage. There is an absolute max above this will destroy the battery, usually both the charger and battery pack have protection against this (as well as undervoltage and overcurrent), unless you're talking about coin cells, which usually don't have any protection due to the low energy levels involved.

I have only used Linear Technology battery chargers, they have a wide variety of chargers and useful information concerning max voltages in their application notes, check them out. By only a battery manufacturer datasheet will tell you exactly what the max voltage is.

The ones I looked at (and the one we are using now) do not seem to have automatic restart feature which I need. In our application the battery may be left in the charger indefinitely.

Thanks for your replies!

bungalow snipped-for-privacy@yahoo.com wrote:

some linear technology batter chargers have this feature(LTC4001), some don't, I don't think there is an easy way to sort them out by this feature though

We did a design using the MAX1737 a couple of years back. The chip will retrigger the charge cycle if the volts drop below a (fixed) threshold. We also fitted the ("desktop") charger with a "restart" button to initiate a charge cycle, as connecting a slightly discharged pack otherwise did zip.