REPLACE GRP 31 BANK WITH GRP 27??

[D A McElwreath]

Hi, c and c 32 has 1 starting bat and 3 house, grp 31, ah 105, ccm 800. They owe me nothing after 11 years but are finally not able to charge or hold a charge. We are doing less cruising, and wonder if I can replace all 4 (they are the same) with grp 27 , which I believe will be lighter, and less expensive. The PO did a good job setting up the charging system and I wonder if I am upsetting the system in some way by replacing the batteries with a smaller physical size and perhaps lower ah and ccm. Many thanks.

[bensolomon]

It won't be an issue at all. Just make sure the batteries are all the same chemistry and voltage. The only thing you might have to adjust is your battery monitor to put in the new set of amp hours so it will be able to calculate for you charging time, amp hours left, etc. Currently it's used to a higher total amp hours, and you'd want to set it to the group 27 amount of amp hours. This is very easy to do and usually well described in the manual. Also, you might have to set the pukert's coefficient on your battery monitor for your new batteries, but once again this is in the manual and if you follow the instructions it's no big deal.

[D A McElwreath]

not sure if you saw my reply. Anyway, I looked on line for the manual to what turns out to be a Bass fuse panel that includes a battery monitor. But I could not find anything. I think it is the one that came with the boat. Now I wonder if I can get by with 1 new start battery and just 2 house batteries. Again, we are not cruising much any more, and even whgen we did, we did not use too much power. This way maybe I would not have to worry about resetting the monitor>> Your thoughts? thanks

[bensolomon]

Originally Posted by D A McElwreath

not sure if you saw my reply. Anyway, I looked on line for the manual to what turns out to be a Bass fuse panel that includes a battery monitor. But I could not find anything. I think it is the one that came with the boat. Now I wonder if I can get by with 1 new start battery and just 2 house batteries. Again, we are not cruising much any more, and even whgen we did, we did not use too much power. This way maybe I would not have to worry about resetting the monitor>> Your thoughts? thanks

You will be fine. That's the setup I have on my boat. Two house group 27s and one starter group 27. We Cruise extensively, but typically end up in the marina every two or three days for a final top off of power. Otherwise, do an engine burn an hour in the morning and an hour in the evening and you should be fine. The most power hungry thing on any sailboat is the refrigerator. If you have a refrigerator, freeze a bunch of 2 l bottles of water and put them in your refrigerator with your groceries. It will reduce the energy draw substantially.

Your starter battery is probably electrically isolated so it only starts the engine. Therefore even if you ran out of house power you could still start your boat. do you know if there's a way to turn off the power to your starter battery?