Is recharging a dry cell possible?

is ordinary dry cell recharging possible ?? have any idea pl help??

Re: Dry cell recharging

I have a commercial unit that claims to do this but it just dous not work. It will lift the voltage on the cell and will give a little bit extra but if you use the cell in a tourch it only lasts seconds.
Barrybear

Re: Dry cell recharging

The manufacturers of ordinary alkaline dry cells warn you to not do it for safety reasons. You can get special rechargeable cells that lose 5% of their capacity each recharge from full discharge. If you use them for 3 recharge cycles or more they are cheaper than ordinary dry cells. One other alternate is NiMH batteries that lose much less than 1% of their capacity each recharge. They have low self discharge currents and so last a long time in consumer products that draw little current like television remote controllers.

Re: Dry cell recharging

It certainly is possible. When I was about 11 years old, an electronics magazine published a very simple circuit that rectified a 50hz voltage and put it through the cells with a high-wattage resistor in series. I used it to charge the 'D' cells in my bicycle lights, they lasted about 2 to 3 hours on a charge (once the initial life was 'used up') and seemed to withstand about 5 recharges before the time dropped significantly.

I now have a commercial MCU controlled unit that definately does work. Torch cells and similar high-usage cells are the ideal ones to recharge. If a cell is drained very slowly, for instance in a remote control, it will usually not recharge as the electrolyte itself has degraded with time.

If I can find the circuit, I will post it, but we are talking about 25 years ago! I'll have a look this weekend.

The key, I remember, was to charge in current pulses, *not* continuous as this could boil the electrolyte. I don't recall the voltage used. Maybe just experiment with low rectified (no smoothing capacitor) AC voltages from a small transformer, remeber the resistor to limit current, until you succeed? Start with a set of equally discharged cells and charge each with a different current, then see how long each lasts with a bulb.

Cheers,
FoxyRick.