# Zapping Rechargeable Batteries - (Bringing to life)

Discussion in 'Power Electronics' started by tomadom, Jan 18, 2013.

41
0
Jan 18, 2013
Hi all

Not sure if I've posted this in the right section.

I have heard that by zapping rechargeable batteries brings dead rechargeables back to life.

I have a 14.8 volt battery pack. What kind of voltage would I need to zap this. Can I use 240 volts? Or, must I find something slightly over the 14.8 volt mark to zap this.

The Amps of the battery pack are 4460 mAh .

2. ### (*steve*)¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥdModerator

25,501
2,841
Jan 21, 2010
This will only work if:

1) you know how to do it.
3) the problem is one that can be fixed by "zapping"
4) you're not concerned about the pack failing again

Asking if you can use 240 volts sounds like you fail at the first step.

The "correct" way to do it is to charge a capacitor of appropriate type and size to a voltage where it will dump perhaps 1 joule of energy into the battery and discharge it through the dead cell.

Then you need to ensure that the cells are all equally charged (which is harder than it sounds)

41
0
Jan 18, 2013
1) you know how to do it.
Of course
Yes
3) the problem is one that can be fixed by "zapping"
Who's to say without zapping them.
4) you're not concerned about the pack failing again
Just squeezing a little more life.

The rechargeable cells wont charge until they're zapped. The zapping removes a buildup of crystals inside the battery which render it useless until it is cleared.
Trying to decide how much voltage is enough.

4. ### (*steve*)¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥdModerator

25,501
2,841
Jan 21, 2010
The "correct" way to do it is to charge a capacitor of appropriate type and size to a voltage where it will dump perhaps 1 joule of energy into the battery and discharge it through the dead cell.

I use a capacitor from an old flash unit (because they're rated for high currents).

They are also rated for high voltages, but you won't need that.

the power = 1/2CV^2, do if you have a 300uF capacitor, the voltage = sqrt(2x/c) (where x is the number of joules of energy and c is the capacitance).

for 1 joule (given the capacitor I suggested) the voltage is sqrt(2/0.0003) = 81 volts.

Practically, I've used voltages as low as 12 volts in the dim dark past when I've done this. (and I'd start from there and work up if required)

The important thing is to then discharge ALL the cells in your battery to zero volts before charging the battery. The capacity of your battery will then be that of the weakest cell. Beware if you have a battery charger that doesn't stop when it detects a cell hitting full charge that you may end up damaging the weak cells next time you discharge the battery.