There are 2 deep cycle batteries in the v-berth that provide power to the bow thruster and anchor windlass. They are 20 years old and I’ve been meaning to replace them for several years, but they were still pulling up the anchor and running the thruster. I did notice the bow thruster would get weaker if I used it for more than 30 seconds, but I tend to not rely on it when getting into and out of the slip, and 15 seconds is more than adequate. But this summer we’re planning on a 2 week trip where there will be lots of anchoring, so I thought now would be a good time to replace them.

I decided on replacing them with the same brand–Optima AGM (blue top) with 900 CCA. The old ones were actually yellow top, which are not the “marine purpose” type but the only difference I could see is the blue top has the optional studs for wire connectors vs just the lugs.

The 2 batteries are parallel connected, so total AHrs is 150. All wires and crimps looked fine so it was an easy replacement. These batteries get charged through a Balmar Digital Duo Charge connected to the House bank. There’s never been a way to monitor these batteries, so if the Balmar charger ever failed, I wouldn’t know it until it was too late and could risk ruining the batteries. A simple voltage monitor with alarm would be a good addition.