SO40 House Batteries

[so40gtb]

Our third "Group 31" house battery, of questionable repute, committed suicide in December while on the hard and under solar charge. So we can soldier on next season with the two other, newer, Group 31s, paralleled, or I can rework the entire battery scheme. Since we don't know the age of the surviving flooded batteries, my inclination is to avoid the chance of failure at the most inopportune moment and rework the system before launch this year.

I'm contemplating removing all batteries from the port and starboard compartments, then relocating the engine start battery, probably to the space inboard of the water heater, and placing a pair of 6V Lifeline AGM batteries in each of the battery compartments, connected to an A/B switch to be mounted on the aft berth bulkhead, just as the other 12V disconnects are. The end result will be two independent 220A house battery banks. A battery failure on one side won't pull down the other side's batteries, as long as we're religious at keeping the A/B switch out of "A+B" mode.



Has anyone else done anything like this? What are your experiences? Is Lifeline the best choice [well, dimensional considerations (height) appear to leave no other AGM choices but for the Chinese Fullriver product]?

Many thanks for any experience that you can share!

--Karl

[Don Reaves]

My boat is an SO35, so the battery situation is less complicated then yours. In 2010, I purchased two 6V Energizer golf cart batteries to replace the two group 24 12V batteries that came with the boat. I bought them at Sam's Club, and they were well under $100 each.

I was concerned about the space available, as they were taller than the original batteries. The only accommodation I had to make was to cut two 1-inch diameter holes in the plywood cover to allow for the extra height of the terminals.

The batteries have been great, and seem to be going strong. I'll never go back to a system that requires putting batteries in parallel. Never.

Don

[On y va]

Same boat, 4x 100Ah Fulmen lead acid batteries.....no problems whatsoever.

I have relocated the starter battery too, to make room for 4 house batteries, instead of 3. Moved the engine starter battery to the port cabin clothes cupboard. But changed from a 100Ah lead acid starter battery, to the 75Ah Optima spiral AGM. Not cheap, but very powerful and a long life span. I had the 45Ah optima red top for 10 years as bow thruster battery.

This 75Ah Optima sits in a battery box in the bottom of the hanging part of the cupboard in the port cabin. This was the closest option, as I didn´t want to loose the space next to the water heater.

Marco

[so40gtb]

I will take a look at the option of placing a battery in the clothing locker/shelving area in the aft berth next weekend. I was contemplating placing the starter battery in the open storage space inboard of the water heater, though that is somewhat far from the engine. It's to the point where I need to go to the boat and measure some possible cable lengths.

I had Optima starter and house batteries on our SO34 and was pleased with them, but they're not the right battery for the SO40 house function.

This is one of those onion-peeling adventures when each day one discovers more things to replace and/or change!

[On y va]

Well.......there is a newer type of Optima, the 75Ah Blue Top version and they are both for starter as service application. I have one as the starter battery now for my Yanmar engine and I am considering (once I actually start my cruise) buying 4 of these as house batteries. As they can take deep unloading much better than lead-acid and they charge quicker, so effectively are more usuable, eventhough u loose some Ah´s.

[so40gtb]

On our SO34.2, I had two Optima Blue Tops for the house, 75AH, I believe, and an Optima Red Top as the starter battery. The Blue Tops were 4 years old and the Red Top 2 years old when we sold her, IIRC. Never any problems with these. I also replaced the factory charger with a Charles Industries programmable-output model when I put the Blue Tops in, so their charging profile when plugged into shore power was correct. I didn't upgrade the alternator on the Yanmar 3GM30F, as its voltage was within the acceptable range for the Optimas, but obviously it didn't do the 3-stage function.