Starting and house batteries

[Halcyon]

Hi all, I have a 03 35TE with twin Yanmar 6LPs. Great boat, had it less than a year and learning a lot. The boat has 3- 8D batteries and its not clear to me what is the design intent of the system. Is it one battery per motor and one house or one starting battery shared and two house batteries?

We intend on anchoring out so more house capacity is desireable. Do the Yanmar's require a 8D to start or can I get by with something lighter? Is it OK to share starting batteries? I only crank one motor at a time.

Can anybody recommend a good source for batteries in the Annapolis area? What is the real difference between the Sportsman Marine 8D battery for $219 from Defender and West's SeaVolt for $417?

The boat currently has it origonal batteries, seven seasons is much longer than I would expect. Two remain strong, reading at the green/white line on the hydrometer, the third just develeoped a dead cell. So its time to replace, what would you do?

Thanks!

[jprohan]

I cruised the bahamas a few trips where we were on the hook every night; sometimes staying a week or more. I had 4 6 volt golf cart batteries linked to make a LARGE 12 volt battery as myn house bank; and one 4 D as a backup starting battery. The golf cart batteries are great because: they are inexpensive ($75-$90) they are meant to be run down and recharged many times. I used to go 4-5 days without having to run my engine to charge them up; they ran refrigeration, lights, vacuflush pump, inverter, etc with no problem, in tropical conditions. They also started my Cummins 6BTA no problem; plus I had the 4D as a backup if necessary. Bought mine at Walmart...believe it or not.

[crowra]

You definitely want to keep starting and house batteries separate. We have two starting batteries -- one for Cummins 210 and one for the generator. We also have a 700 amp hour house battery bank consisting of four 6-volt golf cart batteries. When on the hook, I turn OFF the starting batteries so they remain fully charged. (There is a dial switch with four settings: Off, 1, 2 or both. That switch is off at anchor and both any other time to top off the starting batteries when underway, shore power, etc.) If you have an inverter, you can see how much power you have drained off your house batteries.

My guess is that your configuration has one starting battery for each engine and one for the house battery. Depending on what kind of battery you have, you probably have at least 250 amp hours house. Divide that number in half since you shouldn't discharge your battery more than 50%. 125 amp hours should be sufficient to run your anchor light, fridge, lights, fresh water pump, etc. for the night.

I too am interested in the best place to buy batteries in the Annapolis area. Our choices seem to be Fawcett's and West Marine....

[bccanucker]

Hi: This is a Huuuuge subject to learn everything off a forum.
Re your configuration I'd like to suggest you'll have to trace your wiring because no matter how it came from the builder, a previous owner could have changed it. In my last 2 boats I have changed things to be 1 battery for starting (2 motors or 1 dont care) and 3 for the house batteries. I currently have a 4D for starting my single Cummins 6BT5.9 and 3 sets of 6V US Battery model 2200 golf Cart batteries (232 amphours each pair = 696 amphours) for the house bank. I went to the 6V as the 8D's got too heavy as I got older. As previously said, for longevity of your battery bank dont discharge more than 50% before recharging. I consider having a digital amphour monitor essential. They can be bought quite resonably these days by themselves or come as an option with an inverter. When you have one you can throw away your hydrometer.
We use about 150 amphours per day so with 700amphours /2 =350/150 = 2.4 days. With our solar panels added this year we are charged up at the end of most every day.
Re your bad cell battery--- Battery people will tell you if you're replacing this battery by itself, fine but if it's in parallel with another battery you'l have to replace them both.
In our neck of the ocean we have lots of companies that just sell batteries and it is a real competitive business.
Our electrical configuration is in this post
viewtopic.php?f=7&t=3703&p=21926#p21926