Thread: Reviving Batteries

I wouldn't have thought freezing would work. Cold temperatures tend to make batteries deplete quicker (I got three photos from one set of batteries in Mongolia at one point)

Hi Alistair,

Not freezing. NiCads have can lose capacity if overcharged. This can be reset by a large pulse of current. The designs I have seen have all used 1farad caps to basically blow out the memory. Just be sure to discharge the battery first.

http://www1.electusdistribution.com....ded/nicads.pdf

I went NiMH because of the environmental isseues with NiCads, less prone to deterioration

There is one way to revive old batteries.. You need to jump start them just like a car battery. Get yourself a cheap voltmeter and check how many volts the battery is pulling. A 14.4 v should be over at least 14.4 -15v and 18v should be close to 19v.If your batteries arent pulling that then this is what you do.


The battery you need to do the charging must be higher in voltage than the battery being charged. In other words you need 18v to charge a 14.4v.

All you need to do is connect a wire or lead to the + of one battery and connect it to the + of another. Connect the - of the higher volt battery and then just scrape the wire over the - of the other. You may see some small sparks when you do it. Do this s few times and check the voltage again. If the volts are still low keep scraping. Not sure why this works but it does. My 14.4 v batteries were pulling just 3-4v and held no charge but after doing this they pull over 14v.

If you have 18v batteries you can use 2 x 14.4v. As long as the voltage is higher it will work. Give it a shot, beats spending heaps on new batteries.

If the above doesn't work you can get the batteries repacked.
But last time I tried it wasn't worth it.
It cost me 80% of new and lasted 50% of the time.

The 'Freeze a battery' system would work because there are 2 things which cause 'memory effect' - metal fibers growing thru the inside of the battery causing it to short out internally, and the progressive increase in the size of the crystals in the medium which reduces the storage capacity. Freezing should cause the crystals to break down & possibly break up any metal fibers.

If it doesn't work you haven't lost anything, have you?