I've got some good battery info links on the PC at home so will share as soon as power is restored there, unless I get a major breather here at work to go surf the net a bit. I've been trying to learn a lot about batteries since I'll basically have a wind-generator farm with the new house. In a nutshell though, the Blue Top is more suited for longer drains under light load while the Yellow Top is short drain under high load. Doesn't really explain it well, but the Yellow Top can cycle deeper & harder than the Blue. I better get those links, all my explanations are starting to sound like porn!