DIY Battery Charger from a Welder
One day I had a bright idea. Some people would cringe at this, but I had an old welder that was given to me some time ago. It still welds and I use it from time to time for just that. I had inherited some high-powered diodes, in fact they had already in two heat sinks. They were actually used as an external rectifier for a direct charging alternator. Well I took these and rewired them. There were six diodes for three phases but I only needed four. I used them as a full wave rectifier bridge rectifier and then connected that to the welder. I checked the voltage before hand to make sure that it wasn’t too high and then connected the output to the batteries. I’ve got it charging about thirty-five to forty amps. At the moment I am using it to charge at the rate of twenty-five amps, running off a generator.
Not a very efficient charger, I am sure. But it’s working for me at the moment.
Tags: battery charger, diy charger, welder as battery charger
July 28th, 2008 at 10:16 am
Hi
I too would like to be able to charge/boost charge a 12v battery at 20-35 from a mains voltage (new) welder.
Why are the diodes/rectifier necessary? I thought the output at the weld electrodes is already steady DC (but haven’t measured the voltage)
Can one buy a ready-made bridge rectiifier or a circuit plus diodes and at what point is it wired into the welder output? A quick unplug facility is required I’m sure
Thanks
July 28th, 2008 at 8:25 pm
Mains power welders have AC output unless they specifically are labelled as being a DC welder. Hence the diodes rectifiers are necessary.
Look out for a further post on this topic shortly.