24 v right? While you could make up a battery pack from individual batteries it might be more trouble than you want t get it all into the space.

A mains supply might have to be a bit big to supply the current  however if you are looking at CNC then 24v seems to be popular and it might do double duty.

However there is a nice size of lead acid battery 6V 4.5Ah that is popular in model boating circles so it is relatively easily obtainable at acceptable prices. Make a belt that takes 4 of them in pockets with each battery on a plug/socket and a flying lead and it is still portable. You can use the batteries in your model boat (go on make one). Remember lead acids MUST be given a charge every week.

Edited By Bazyle on 10/03/2012 16:59:16

There was way back when a series in the Model Engineer which showed you how to build your own NICAD battery reconditioner. I did not build one as I had such a thing included in my Video camera. NICADS seem to 'form a memory' of its charge/discharge cycles. What the thing did was a series of charge-discharge cycles. But as good things go they both went. The camera was broken when someone knocked it out of her hands and she would not use the lanyard. The charger was lost when a Hungarian left it out in a thunderstorm. he forgot it or did not want to get his 'T' shirt damp.

Have a look for the thing if you know where the ME indexes are

Rgds

Dick

Hi Sid

I think you meant to aim your question at me rather than Dick.

When I bought the cells to rebuild the battery for the drill, I got the type that have "solder tags". In practice the "tags" are strips of metal that could fold over the battery length ways and nearly touch – but they stop just clear of each other. So they are much bigger than what I used to know as "solder tags", but you can soft solder these quite easily to make up the pack. If you need to get them to a funny angle then fold them over with a pair of pliers and flatten them well down. To extend the reach of the tag then a bit of – ideally- copper shim would suit or a bit of brass. The main thing I found was that they have to be packed together very tighly to go back into the battery housing. It's better to work on that aspect first and then sort out the interconnections afterwards, but all quite do-able on the kitchen table, you don't need an electrical workshop.

Keith

I zapped a few of my totally dead 'Performance Power' (B&Q) 18V batteries with an arc welder, and another time a fully charged car battery and heavy jump leads, worked a treat!

They didn't explode, but got pretty hot mind, and once allowed to cool they recharged like good-uns!!

If you Google 'reviving dead ni-cad batteries' or similar, you'll come up with more hits and U-Tube videos than you can trawl in a lifetime!

You may have totally dud cells in the pack, in which case the routine won't work, but you've lost nothing if it doesn't, and gained a working power tool again if it does, 3 out of 4 of mine got revived, and the one that didn't got new cells cheap courtesy of battery packs bought off eBay, which I split down.

John.

Hi Bob,

I did the same as Keith, opened up the battery pack and replaced just one leaking cel. the whole thing worked well for a long time afterwards. It's not rocket science and soldering is easy and works perfectly.

Reards

Terry

I used to solder these packs up in my radio controlled cars days. The cells used are almost exclusively sub C size, the best way to solder them is with multicore soft solder and a relatively large soldering iron, as said before, with minimal time on the cell. I use a 40 watt Weller, commonly available.

Good luck with your fix!

Slightly off topic, but re soldering connecting wires directly onto cells is not good practice and DO NOT do it on Lithium cells unless they have tags and even then make sure you are quick.

The results can be explosive and I can assure you that the amount of energy and toxic smoke released from even an AA size cell is amazing and could easily put you and your workshop out of action!

This does not apply to the rechargeable Lithium Ion cells that might be found in drill batteries but still take care not to overheat the cell which can easily happen if they don't have tags. (connecting tags are spot welded on for a reason which is not just related to cost).

Another thing to watch out for is that some batteries have thermistors and diodes built in for protection, make sure these are retained if replacing cells.

John Shepherd

In Christchurch (NZ) we have a battery shop who will reload battery packs for about half the price of a new pack, and at least double the Ahr rating. Last one I had done was my ancient cell phone, before that, a hedge cutter, and a cam corder.

You can get a bit more life from a battery if you put the battery in the freezer for 12hrs, take it out and leave it for 12 hrs then recharge. Another way is to zap each cell with a charged up electrolitic capacitor, that involves breaking open the battery pack. This last method burns off small filaments of nickle that short out the battery internally. Ian S C

It doesn't matter whether I store them charged or not. When I come to use them the damn things are always flat!

Russell.

Hi Bob.

Sub "C" NiMH are available but a quick price check here in Australia through an electronics outlet would drop about $180 AU out of the bank account to buy the 20 needed to attain 24v.

Yes there are probably cheaper here and in the UK so shop around !

The charger could also be what has killed the batteries as many battery packs don't have the internal temperature thermistor either fitted or connected (that is what the third terminal on the battery is for ) and some chargers don't have this third terminal fitted either .

This is to protect the battery pack from overheating when charging which kills batteries pretty quickly .

An Electonics magazine (silicon chip ) i read did some stories on this and also produced a charger kit that was available through Jaycar electronics but i'm sure Elektor magazine did the same in the UK .

A later edition saw an old battery drill revived with the use of 2 gell cell batteries mounted in a small plwood box with a carry handle on top , it was not as convenient as the drill with an internal battery but still had its uses as you did not need mains power to run it or have to run power leads everywhere .

IAN

A friendly word of warning.

DO NOT try to replace the Ni-Cads with NIMH batteries and think that the existing charger will be okay

It will not !!

doing this may well result in the batteries exploding.

NIMH battery chargers are designed specifically for NIMH and closely regulate the voltage and current.

Ni-Cad chargers are not nearly so carefully regulated.

Like I said, just a friendly warning

I would hate to see anyone get hurt.