Electronic – Is it ok to keep rechargeable batteries in an unplugged charger


Is it ok to keep rechargeable batteries in an unplugged charger considering possibility of discharging the batteries via the charger's circuitry, etc.

Best Answer

I'd expect it to be OK in many cases - BUT no guarantees as it depends on the charger designer. If the charger was powered you'd hope most designers would place the cell in a neutral mode. You'd hope. Unpowered it is not hard to draw almost zero current, should the designer care and 'know their stuff'.

An experiment:

Your question is easily answered in a specific case by an experiment.

Place a battery in the unplugged charger with a small piece of paper between battery +ve nipple and +ve charger electrode so that the battery is isolated by the paper.
Set a multimeter to lowest current range and connect probes between charger +ve and battery +ve.
A well designed charger should produce at most < 100 uA and it would be easy to get this < 10 uA and not hard at all to get < or << 1 uA.

If smoke comes out of the meter while performing this test the charger is (or was) of an inferior design.

Lacking a low enough range ammeter, use a voltmeter - play to see what range gves highest reading. Now try eg a 1 megohm and 10 megohm resistor in series with bttery and meter and see how they compare.