My beloved and trusty Makita cordless drill and impact driver has reached the point where the batteries (3 of them, 14.4V) are only giving a few minutes' continuous use before they require recharging. As they are still over £20 a pop, is there a cunning trick I can use to restore some charge time?

Probably not. These are I suspect nicads, and the physical changes in the cells caused by the charging eventually destroys the cell.

Warning: don't try and replace them with batteries of a different chemistry: you won't be able to charge them safely (risk of fire/explosion) or possibly at all.

Thanks Neil, I figured as much.
They are NiCads, but I wouldn't replace them with anything else. I actually don't like the Li-on ones I've used - the balance is all wrong.

ASDA were/are doing a Draper 14.4v drill for about £15ish recently.

I got one.

Thanks, Gripped, but I love my Makita and really don't want to get another, especially as the actual units are in fine shape. I just wondered about the battery life.

You sir, are crazy..

I think it's just what you're used to. Undoubtedly the Li-On ones are lighter and last longer, but I'm used to the weight of mine and the big battery balances the weight of the motor gubbins.

Mr Clennell, does your battery pack contain anything other then the 12 cells that make the pack? If not, and you may already be aware, 'C' sized Ni-Cad cells are widely available to the RC model world. It may be possible you could replace the defective cells.

To be honest, Mr zkom, I've never investigated what lies beneath the pretty red and grey casing. But it's an interesting thought...

Just a little thought for you. You could potentially just have 1 or 2 weak cells bringing the whole pack down. Whether or not you're able to replace individual cells I'm unsure. They may all be tagged together.

I imagine Mr Barnacle will advise against it. Well, advise *ME* against it.

It's just that Mr Barnacle can foresee a telephone call from Reception... "There's a bloke here with a fistful of smoking batteries to see you."

It's probably worth opening the pack to see what's in there. Though it is probably cheaper and certainly simpler to spring for a new battery.

D'OH! You know me too well!

I've done that with rechargeable touches before. Opened up and replaced blank cells with conventional AA rechargeables.

I bet Maplin could have something.

I rebatteried my NiCad cordless screwdriver.
Cells were the C size and there were something like 12 arranged in an interesting configuration. (2 in the bit that slots into the handle, maybe 10 in the fatter base)
The cells have tabs so you can solder wires between them.

The other thing I did was to uprate them, so there's a mAh rating on them and I went a bit higher. I think the batteries cost about £6 - £7 and the fiddling around to get it to work was a couple of hours.

Replacing the battery with another one would have been about £20 so it was a marginal gain but always good to have a dig around and find out how stuff works.

I've also done laptop batteries - that was a fair bit more difficult /dangerous trying to solder wires directly onto Li-Ion cells, and not really worth the hassle. Performance was not all that good afterwards either.

Whilst I would be tempted to have a go, this does ring true: