reviving cordless batteries?

tomdempsey200

anyone have success reviving faded ni-mh batteries ?

cost of getting them 'recelled' seems to be about 100 so not worth it

had a laugh watching this...notice the way he carefully checks both sides of the
battery pack for bad contacts and labels his repaired batterys when finished
http://www.youtube.com/watch?v=yGmTBsIrXME

Bruthal

I have recovered ni-mh batteries by connecting to a supply in series with ammeter and bring the current up to about 100 ma. A variable power supply is required Since the current will reduce quickly at first as the batteries charge a little.

The batteries own charger probably won't recognise them as batteries until you get their voltage up close to their nominal voltage, which can be done as above.

They may not perform well, if at all if they have been left completely discharged for a long period.

tomdempsey200

they're not actually dead

they're only good for drilling a few holes after charging

i checked the cell contacts anyhow ..they were all ok

Bruthal

Yea they are not recoverable to a useful level for power tools really once their capacity is noticeably reduced. You could make up a pack yourself by getting NiMH cells with tabs to solder them together. Especially if you can get the battery case opened on existing batteries.

tomdempsey200

they're easy enough to open and disassemble

i wonder how much the cells would cost

not worth getting it recelled for a hundred anyhow even though they're bring it up to 3AH from 2.6

Bruthal

This page has NiMH battery packs of varying types, a suitable one could be taken apart and put together with other ones. What voltage is the battery? 15 aa 2.3ah batteries in series gives 18v nominal 2.3ah for example, and could be made from 3 packs of the 9th in list in link, the 6v pack which is made from 5 cells

I ordered plenty of lithium batteries from that site the last few years.

tomdempsey200

24v 2.6 ampere-hours

tomdempsey200

what combo would be used to make a 24V 3Ah pack?

when i enquired they said the 24v/2.6 would be upgraded to a 3Ah when 're-celled'

Bruthal

tomdempsey200 wrote: »

what combo would be used to make a 24V 3Ah pack?

when i enquired they said the 24v/2.6 would be upgraded to a 3Ah when 're-celled'

24 volt would likely be 16 x 1.2v NiMH cells in series. Fully charged would be 24 volts.

So 16 AA cells of 3ah each would give a 24 v 3ah battery.

Or 2 sets of 16AA cells 1.5 ah with both sets in parallel would also give the same battery. Open your old one and check the cells setup.

They might be 15 cells either, with a true charged voltage of 22.5v. Open it and see.