Battery life or how can they be dead when we only had the lights on…

One good thing was that the boat came with relatively new Rolls AGM batteries. These seemed in reasonable condition and they were split as a dedicated engine start battery and two bags of 4x110Ah batteries dedicated to domestic supply and the winches. Having done some research on battery charging, we decided that we would never want to reduce the batteries below 50% which means that we effectively have 200Ah of usable energy if the batteries are fully charged.

The moody has over 30 lights which are 10W. If these are left on for an hour that is 300W which at 12V is 25Ah. You can probably see where this is going….. If I switch the lights on I use up all my battery power!

One of the first jobs on the Dufour had been to change all of the bulbs to replacement LED bulbs which draw a tenth of the power. It was clear that this was something that was needed on the Moody immediately. We opted for warm white bulbs to give a softer light and these have been excellent. At the same time, we changed all of the navigation lights to LED too so at least our lighting is optimal.

The winches draw a lot of power when they are used but a dedicated battery bank did seem excessive especially as we have winch handles! So it seemed sensible to consolidate the battery banks and use these across all uses. A second idiosyncrasy with the Moody is that the service battery bank is above the keel, not a bad place to have quite a bit of weight. The second bank is under the aft master cabin bed! So it wasn’t just that I had put some weight on that had led to the stern being lower in the water. There is a slot available aft of the existing battery bank and before the engine room where the second bank could be located. This seemed sensible from an electrical perspective and with a view to weight distribution. Moving a couple of pumps, which also simplified pipe work, was all that was required to make this change happen.

So now we have 800Ah of batteries for our winches and domestic use.

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