Toto

Great, thanks for the info everyone, I know the new stuffs a lot better but I just hate binning perfectly good tools!

So 3 volts isn't a big deal then? just out of interest what would be too much?

OK, maybe I'll just run the battery out under low load until it's had a couple of charges then. Its a Draper expert BTW, this model I think. http://www.amazon.co.uk/Draper-41407-14-4-Volt-Combination-Batteries/dp/B000PJAN4Y

I had a number of dead battery packs on a couple of cordless drills that were going to cost £300 to replace so I bought a load of cells to rebuild them myself. http://www.amazon.co.uk/gp/product/B00H2GQFOA?psc=1&redirect=true&ref_=oh_aui_detailpage_o00_s00 These are listed as 1.2v, the same as the originals but when I built the 14.4 volt pack up and checked the voltage it was 17.5v. I built a second pack to make sure I hadn't damaged the first but again, 17.5v. When I checked the individual cells they were showing 1.45v instead of 1.2v. I don't know whether or not I should drain these packs and put them through a couple of charge cycle to see if that makes a difference because I don't want to risk burning the drill out. Does anyone know how tolerant a cordless drill is to voltage increases? I could take a couple of cells out and drop the voltage to 14.5 ish but obviously I'll lose storage capacity and if the voltage drops naturally with time I'll lose power too. Any help would be appreciated.