[MULESHOESINC]

well was plugging my truck in one night and got to thinking what if i could power the block heater with the truck maybe a 3rd battery strickly for the heater but i dont know if i would have to have an extra alternator with it... i figured i would ask you guys and see what ideas you would have for trying a set up for something like this all suggestions greatly appreciated

 

[chuckster57]

It's been discussed before

Here is the thread:
http://www.thedieselstop.com/forums/f24/running-block-heater-off-power-inverter-216944/

 

[Mark Kovalsky]

That will work fine as long as the engine is running to turn the alternator. The block heater draws enough power that a battery won't be able to power it for very long before dying.