John, As you are well aware, any system of regulating electricity that involves any type resistor (other than those wee little fellows in electronic circuits) gobbles up power just like the regulated device does, just turns it into heat instead of usable power.. I ain't an electronic wizard as I lose the electrons when they get into them diodes etc, but I have designed many control circuits for 12 volts up to 440 volts AC. I suggest you find some electronic brain who can design you a circuit that does not employ heavy resistors, but instead, it regulates electronically and also has regenerative braking to help keep your batteries charged longer. Surely someone out here in the model engineering world can come up with something that will be capable of handling the load. Jesse the REDNECK over in the New World I'm not sure how to make a carbon pile regulator, but I imagine there must be something on the net. It's old technology after all. Just a couple of other thoughts.. 1)rotary stud switch with home made BSRs (big sweaty resistors), perhaps from a scrap electric fire. I haven't done any sums on this, I suspect you'd need several in parallel to take the current. 2)I looked at some fork lift truck control circuits many years ago. In those days the only high current device available was a thyristor, which was fine for turning on but needed something a bit clever for switching off. From memory, one thyristor was turned on, and to turn it off, another thyristor in parallel shorted it out (the only way to turn them off was to remove the supply or let the current drop to zero). The cunning thing was that this second thyristor had a capacitor in series, which charged up to the supply voltage. At this point the current in the second thyristor fell to zero, so it too turned off. I seem to remember the capacitor was referred to as a commutating capacitor. One obvious question is how the second thyristor turns off the first - I guess something is arranged to ensure that the volts drop across the second is less than the first. You've whetted my appetite so I'll have a rummage on the web and see what I can find. JohnP MODEL ENGINEERING DISCUSSION LIST. To UNSUBSCRIBE from this list, send a blank email to, modeleng-request@xxxxxxxxxxxxx with the word "unsubscribe" in the subject line.