Cars, trucks, RVs, and motorhomes run dual 12-volt batteries for various reasons. Depending on how you wire a two-battery 12-volt system, the result can be a 12-volt system or a 24-volt system—or even ...

For most of us, purchasing a vehicle and leaving things untouched is nigh on impossible. Apparently it's ingrained in our hot rod DNA to mess with things better left alone. Sometimes, however, it's ...

Here is a simple mod to allow the speed of any 12V fan to be varied. All we need to do is insert a rheostat or variable resistor in the 12V wire to the fan. The rheostat should be rated at least 3 ...