Hi all, RR here. I have been asked to try and fix a "1 hour" ni-cad charger for an 18 volt battery drill and I was appalled at what I found inside. There is just a transformer feeding a bridge rectifier made from four 1N54xx diodes and a 47 ohm resistor which is shorted out to start with by relay contacts which are triggered to open and place the resistor in series when a temperature sensor in the battery pack opens and triggers the relay. So there is no current limiting at all, just raw unsmoothed and uncontrolled DC feeding direct to a pack of 15 ni-cad cells, and of course what happens is that some of the cells short out and therefore remain cold and this causes more current to flow through the pack and heat it up even more and what I've sometimes found with crude charging systems like this is it's often the cell(s) nearest to the sensor that short out so then there is no longer any temperature monitoring of the remaining working cells so the rest of the pack can heat up to a point where it could explode! Isn't it about time the relevant authorities cracked down on stuff like this? Don't ni-cad and ni-mh cells need constant current controlled by some kind of current limiter, preferably with a regulator of some sort and not just a resistor as this doesn't keep the current limited enough if some cells short out? RR.