I also posted this in the Evinrude forum.

I have a 31 series Sear Diehard battery for my crank that is less then 6 months old. When I went to the lake today for the first time after my new powerhead. I turned the key and the volt gauge showed 10v even though I just pulled the boat off of the charger when I left the house for the 30min run to the lake and the boat had been on the charger for 2.5 days and all the batteries were green. The motor barely started. While running the motor would charge the battery but if I held the trim down for a period of time I could watch the volt gauge go from 15v to 10v.

Any thoughts if I might have a constant draw on the battery that is causing the issue or is it just a bad battery or bad charger. Thanks