I recently installed a 400 watt inverter (cigarette lighter plugin) into my entertainment center to run my TV and DVD player at night without using my generator. The TV and DVD player power up fine with AC power or generator on, but will not power up the TV or DVD without it. So I have had to turn my inverter on, power up my TV and DVD, and then shut my generator down. It works fine all evening and only uses 1/4 of my battery power. Will a 500 watt inverter correct this problem? Or do I need to check something else ???