12 volts is 12 volts, whether it comes from a car or leisure battery. My 'system' (just a diy jobbie) has been connected to my van battery since i started in November 09. I only had trouble with a flat battery once, and that was with me leaving rear doors open with the internal lights left on, I now have them turned off and have had no trouble, But i have little very compact work, so the van is travelling a fair bit, so i suppose it gets boosted regularly.