When I was a company driver we had Internationals with 3 batteries and Webasto 2010 heaters. Those would run the battery down if you ran them more than 8 hours especially when the batteries got older. Those heaters heated the whole system not just the cab and they only needed about an 1/2 hour to preheat a n-14 style Cummins to start. They were overkill to use as a cab heater. The new 2 piece ones (seperate engine and cab heaters) are a lot smaller and more efficient. If the cab heater or engine heater (when used for preheating eg. 1 to 3 hours) is running down batteries overnight IMO there is a problem somewhere else. I run 4 CAT branded batteries and get about 3 1/2 years out of them before they stop holding a charge. I ran 1000 CCA ones before but the new set is 800. They say thats the right ones to use when you have an invertor,tv,etc. We'll see if they do better.

Last spring, when I went to put in the optima's, the Interstate Batteries shop where I bought them, suggested going with the Blue Top's, because they hold more energy than the Yellow's do. I have 4 of them, and no problems so far.

Back in November, I left the florescent over-heads on for some reason, and didn't get back to the truck for 5 days. Because I had the curtain up over the windows, nobody saw the lights on...so no-one called to tell me those lights were one...thought for sure that the batteries would be dead enough to not start the engine, when I opened the door and saw those lights on. The truck fired right up.