Windlass and thruster Battery question
- Thread starter xavpil
- Start date
Hi,
I was in a similar position back in 2021. I bought my 2011 boat, sailed her home, and quickly found out that the 4 house batteries and the 2 windlass / thruster batteries were dead. I wasn't sure exactly what I wanted, and after buying the boat I didn't have a lot of cash left. For the windlass / thruster I bought 2 of these
EverStart Lead Acid Marine & RV Deep Cycle Battery, Group Size 27DC 12 Volt, 750 MCA
In stock at a local walmart, under $100.
I don't anchor often, so the windlass doesn't get used much, I use the thruster occasionally. In the three seasons I have had those batteries, they have worked just fine.
Barry
I was in a similar position back in 2021. I bought my 2011 boat, sailed her home, and quickly found out that the 4 house batteries and the 2 windlass / thruster batteries were dead. I wasn't sure exactly what I wanted, and after buying the boat I didn't have a lot of cash left. For the windlass / thruster I bought 2 of these
EverStart Lead Acid Marine & RV Deep Cycle Battery, Group Size 27DC 12 Volt, 750 MCA
In stock at a local walmart, under $100.
I don't anchor often, so the windlass doesn't get used much, I use the thruster occasionally. In the three seasons I have had those batteries, they have worked just fine.
Barry
My thruster is powered from a Group 24 battery in the v berth. My windlass is powered from the house bank. Both only work when the engine is running so there’s minimal drain from the batteries - they’re only needed to absorbs the quick power surge. If your house bank is lead acid (flooded, AGM, or Gel) it would be best to match that with the aux battery so the charging profiles match.
I need to correct myself - My thruster battery is a Group 27. I was thinking of my Group 24 start battery. All of mine are AGM, though not the Odyssey AGM Maine Sail mentioned, just Deka / East Penn / West Marine AGM.
Ours came that way from the dealer. I assume the size would be directed by the amp draw of the thruster.
I'd start by measuring the space provided for the battery. Bigger may be better, but not always necessary. How you choose is often a personal decision. If I had space for a grp 27 but the math says grp 24 is adequate, I would usually look at the price difference and choose the larger battery if the difference is just a few dollars. But that is my methodology. You get to choose your own! Barry and David might choose the smaller battery for the weight difference because they like to race their boats!
With lead acid batteries, weight is an issue for my old, tired muscles. I don't want to try to lift more than a Group 24 (60lbs). But LiFePO batteries are about 40% of the weight, so I willing to go with a bigger size as long as I have room and the weight doesn't go over 40lbs. That's on my RV. For my 19ft Mariner, 100AH in lithium is more than adequate. Since I'm starting from scratch on the Mariner (no electrical system at all), there's no existing lead acid charger/converter to deal with. LiFePO just makes so much more sense, especially when considering acid spills from excessive heel on a small boat with lead acid batteries.
Fred W
Stuart Mariner 19 #4133 Sweet P
Fred W
Stuart Mariner 19 #4133 Sweet P
LFP batteries are not well suited for high short duration loads. The BMS is the limiting factor. If the BMS detects an excessively high load, it will shut down the battery or burn up. Neither are desirable outcomes. LFPs come into their own for house loads, long duration low amperage loads.
Our house bank (two 8D AGMs) supplies power to the windlass. Hunter rigged the boat this way and has worked just fine over the years anchoring hundreds of times in PNW waters.