I have A Nuvi 550 with the bare-wire hookup. I'd rather not put it on a switched circuit. I'd like to go directly to the battery, but I'm not sure if the voltage-reduction module in that wire will be a permanent power draw. Garmin support tells me they think it will stop drawing once the Nuvi battery is fully charged, but they weren't sure. They said if I unhooked the cable from the Nuvi that would stop any draw as well. I'd rather not have to bother with that. Does anyone know if this thing will be a permanent power drain?