Well, It's been said here before and on the old stie how important it is to have to solid matched batteries. My Tahoe came with two Interstate megatrons(Junk IMO) in it when I got it. Since day one the truck never started that great compared to my 2000(which olddly enough has cheapo walmart batteries in it.) Well we got our first shot of cold weather in CT and the Tahoe wouldn't start. Went down to Sears and got two brand new Die Easys gold series and that truck turns over like a SOB now. What a difference. I have never had any luck with Interstate batteries. Anything I have ever worked on over the years with any kind of starting / charging problems that had interstate batteries, they were the cause. They are not that old either. But let that be the lessson. Two new matched batteries are a must.