To do a secondary battery, you will need to do some wiring, need a isolator thingy to regulate the charging from the alternator between the main and 2nd battery. You probably need to go for a maintenance free dry battery, install them at the boot, vent them properly and cover it properly to prevent it from being a fire hazzard.

Me, I would just go for a Optima yellow/red top and forget about adding a 2nd battery. Try not to use the system more then 10 minutes with the engine off.

Thats the main reason I dont get it, why anyone would install a DVD on the car dash, cant watch it while driving, its a distraction, cant watch it while car is not running as it will drain the battery, watch it for 2 hours with engine running, waste of fuel and might cause CO poisoning if in an enclose area.

Install a LCD for the kids at the rear is the only reason valid for me.



Forget about installing a capacitor, it will only drain your battery faster if you watch movie with the engine off.