I've been having some problems with my #1 battery in my 2 battery bank, when I switch to 1 only, I can't start my little 2GM20F engine... switching to 2 or both and it starts fine. So I pulled the batteries yesterday to check and test them. I have a hydrometer and plan on testing all the cells this evening. (charged overnight, so waiting for a "rest period" before testing specific gravity)

Are there any other ways to test a battery? I would love to load test it, but I have no idea how. (I seem to recall something using a bank of lamps... but I don't recall details)

Oddly neither battery has any sort of mark indicating the date it was put into use. Both are Group 27, and are pretty much the low end flooded cell batteries from WM. I have had the boat 2 years now, which is all the history I have on the batteries.

Does WM load test?

Any ideas?