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Old 09-28-2022, 07:54 AM   #18
Hippocampus
Guru
 
City: Newport, R.I.
Vessel Name: Hippocampus
Vessel Model: Nordic Tug 42
Join Date: Jul 2020
Posts: 3,892
When we bought our current boat it had a FLA battery for the windlass and bow thruster. I repetitively blew the ANL fuse if you used the thruster too much. Connections were fine as was wiring size. I don’t like FLA on a boat. Especially someplace where there’s the potential for a lot of motion. That battery is under the sole in the forward stateroom. So I replaced it with a lifeline AGM. Now the fuse doesn’t blow and there’s a lot less brush dust from the thruster. Also windlass performance improvement occurred.
Think both thruster and windlass are sensitive to voltage drop. Think you get less volt drop with a battery in good condition and having the engine running. Agree you always have the engine on when using either. Don’t think even a high output alternator is adequate to keep voltages up without going to a separate battery. Think that’s due to multiple factors. We will use the thruster and the windlass together. Like no angle when retrieving or laying down chain. With the battery forward wiring runs are very short and the battery starts the exercise at 100% soc. Life is good.
We like to leave early in the day. That’s when our house bank is at its lowest. Constant draw over night and nothing coming in from genset, solar or alternator. Given the size of the house bank don’t think asking it to run the windlass and thrusters then is a good idea. Probably could increase the size of the house bank but rather have the boat not list (that bank is in the starboard side of the ER) and need the weight of the forward battery to not be dragging our butt.
Think the size of the alternator doesn’t matter once you’re past rate of acceptance of the battery. Some folks have very large house banks or have Li so this is a non issue. We don’t so get by with separate batteries for the bow functions, another for the genset, another for the stern thruster, another for main engine with the house bank only doing hotel loads. A side benefit is we can switch loads around so will always be able to be functional if any one bank or battery goes bad.
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