billcruise wrote:
I have 3 Optima D31M batteries which are 8 years old. One is house/gen, one port engine start, one stbd engine start. I would like to connect two in parallel and have them serve as the house battery and use the remaining batter for starting port and stbd engines. Is this a bad idea?
I would say no. I have the same setup but without the getset, I have a inverter. Below is from one of my past postings so I don't have to retype it. My inverter load, could be your house load. Also, you never want the batteries permanently hard wired toghter.
"I have 3 batteries, one for starting, one for the house, and one for the inverter. All 3 can be used by them selves or tied together. The boat came with a dual system, I add the 3rd battery connecting it the the 2nd battery using a dual battery switch. The "BOTH" side of the switch is connected to the inverter. Since the inverts load could be high (what are you tiring to power?) I set the 2nd switch to both. NOW the inverter is using the #2 & #3 battery. #1 is reserved for starting!!!
If both dual switch are set to both with the engine running, all 3 batteries will be charging. I like using the combiners, the 2 combiners have a remote wire. I connected the remote wire (14G so its fairly light) to a switch on the helm. It is a 3-way, so I can set the combiners to OFF-ON-AUTO. With the engine running and the 1st dual battery switch set to #1 and the other to off. I can select to charge other batteries or not by the switch."
Hope this helps.