Looks like a good idea, but I don't know if I need one. When the low batt light comes on, i just turn off everything and give it some gas for a minute or so.

I checked my voltage in diagnostic mode, with everything running (all three headlights, driving lights, and handwarmers) the voltage is below 12 at idle, but goes well above at around 3000 rpm. So when I am stopped or going really slow I turn off the extra stuff.