Could I add a third battery to my port array? [2007 310DA]

[mobocracy]

After four summers, my port side batteries (which run the house power) are getting to the end of their useful life. Long afternoon anchoring now results in a port engine that won't turn over without pressing the "emergency" crossover switch.

Would it work to parallel in a third battery for the port side to gain a bit more durability out of the port side?

If it was just me, I would run the generator more often but the admiral gripes that it's too loud and we're really not out at anchor long enough for it to matter, except near the end of our fourth summer. I wish there was space to just move up to 4D batteries, but there's not really space for it without building some kind of rack, which sounds dubious given the mass and forces involved.

My cheap-o thinking with 3 batteries is to just steal the second battery from the starboard side so that the port side is 3 batteries, starboard 1. This gives me more depth for house power without really risking much since I don't think the starboard batteries power anything besides nav/anchor lites. Plus it means I get more port side power in the same identical battery footprint.

 

[Harry Williams]

3,4,5...you can add as many as you want, As long as they are all the same. And when i say the same, i mean the same everything including year built. That's your best bet.

 

[mobocracy]

3,4,5...you can add as many as you want, As long as they are all the same. And when i say the same, i mean the same everything including year built. That's your best bet.

Yeah, I know enough that they needed to be identical as possible (maybe down to lot numbers) to avoid problems, but I wasn't sure if 3 in parallel would be an issue for, say, the port engine alternator.

 

[Bt Doctur]

would be better of dedicating the engine batteries and have a seperate house

 

[mobocracy]

would be better of dedicating the engine batteries and have a seperate house

I kind of looked at this and it seems like a ton of work to split it up this way. I wish it had been done like this from the factory.

 

[Creekwood]

Three in parallel will be fine if you have the space. Its really important that they are all exactly the same though or they will not last. Your alternator will be fine.

You may want to upgrade your battery charger though. Generally chargers should be 10-15% of the total amp hour capacity of the bank. More is not good and less is not good. So lets say you have 3 group 27s that are dual duty (deep/crank) with 80 amp hours each - 240 total. Your charger should be able to push 24 to 36 amps to that one bank at a time during bulk loading charging stage. Most chargers split the output and the smart ones will push the full amps to the bank that is low. So your starboard non-house will probably be full or close and won't draw much of the charge amps. You may want to go with a 40 amp 3 bank charger, but at least a 30 amp. The new smart chargers are much better for battery life. So if you have an older one, might be time for an upgrade.