We went for a nice overnight in Manzanita Bay. Being moored in Kitsap is providing some unexpected advantages. While Shilshole is a better location for just about any trip, you have to deal with the open Sound, making weather windows a bigger issue – even for overnights. Liberty Bay and Port Orchard are part of the more sheltered western side of the Sound – protected by the islands and Kitsap peninsula. When there are 4′ rollers on the East side of Bainbridge, the West side can be relatively calm. So, we cruised 3.5 miles from our marina to drop anchor 2.6 miles from our house (as the crow flies) for a lovely, sheltered night (weather was from the S/SE, so we were sheltered by the bay).

This gave me a chance to gather some data on power consumption during the “worst-case scenario” – hydronic heat running 24/7 and no sun for the solar panels. We dropped anchor at 2:20 pm with 100% charge in our 600AH AGM house bank. Over the course of the day, we did zero power conservation – we ran the hydronic heat, left the navigation electronics on, (so we had the anchor drag alarm), and we even streamed a movie (the Dark Knight – our little cellular connection really struggled). Depending on whether the heat and/or fridge were running, we were consuming between 12 and 20 amps at any given time. The solar panels were putting out less than an amp.

At 7am, the banks were down to 53%, meaning we’d used about 280 amp hours over 16.5 hours, or about 17 amps per hour. We ran the generator for two hours, returning the banks to 73% – about 60 amps per hour (or 10% charge per hour). This seems a little slow for bulk charging, but isn’t that far off from what I expected.

All-in-all its about what I expected. A few thoughts.

  • The solar panels can make a huge difference. During our summer cruise, on bright days, I saw them putting out 18-20 amps at 14V, which would pretty much run the boat and recharge the batteries. Realistically, they do about 6-8 amps for most of the day, which is enough to run the fridge.
  • The 24V charger was drawing a surprising amount – this system transfers power from the house bank to the windlass/thruster banks via the inverter. It was hard to get a precise measurement, but I’d say 3-5 amps.
  • The hydronic + fridge drew between 6 and 10 amps.
  • TLDR; in winter at anchor, we’ll need to run the generator for 2-3 hours per day. We can probably optimize this a little, but not much.
  • In summer at anchor, we’ll need to run the generator for 1-2 hours every-other-day. With a lot of sun, the panels put out plenty of power and – coupled with not needing the heat – there’s a chance we could go for several days without needing the generator.