Thanks for all the great replies guys! The new Minn Kota 3 bank charger showed up yesterday and I got it installed. Once the cranking battery has a full charge I'll pull it out and get it tested.
Still not 100% sure on what I'll do if I need to replace it. The cost of just replacing it with another cranking battery seems nice but if I'm constantly draining it with the electronics I'm sure I'll be replacing it again sooner than later. On the other hand I can get a decent cranking battery for around $100 and I could replace it 3 times for the cost of the Optima D31.
I'm using it to crank a 115 Opti (this is why I didn't pull start it) and the manual says it needs a minimum of 1000mca. It seems to be more picky about voltage than the mca. Last year when it died on me the motor was cranking but I got no beep when I turned the ignition on so I assume that the computer wasn't seeing a high enough voltage. I put a meter on it when I got home that day and it was still reading over 12v.
To me it seems like this would be the intended use for a dual purpose battery but from what I've read a lot of folks say they do a decent job as a cranking and/or deep cycle but they're not really great at either. Guess I'll wait to see how the current battery tests and then make a decision. Based on the replies here, and the $$ I'll probably just go with another cranking battery and see how long it lasts.
One thing is for sure... I'll definitely have a set of booster cables on board this year! Anyone know if there are any issues with boosting from a single battery that is wired in series with another? I know I only use the single battery to get 12v but should I remove the cable between the 2 batteries that are in series before I boost?
Thanks for the offer Paul. I may take you up on it. We can talk when I pick up those Northam's from ya.
Cheers
