Battery switches on 361

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Feb 26, 2007
Beneteau 361 Quebec
Hi, I have a Beneteau 361 year 2000 with 2 battery switches, one for house and the other for starting the engine (a third one is for the ground and always on).
There is a link between them that combines them. I understand that they have to be on for the alternator to charge the batteries. If you close (OFF) the start battery switch the alternator will only charge the house battery and vice versa. When they are both ON, the alternator will charge both battery bank and I think that this is a problem. Since the start battery is always almost full and requires very little charging won't the regulator in the alternator reduce the charging voltage and current to the house battery? Someone told me that the start battery would discharge into the house battery bank and both would start charging from that point. I have 500Ah AGM house battery bank and 100Ah AGM start battery I am afraid that the alternator might not charge the house battery completly.

I thought that I should install a BlueSea remote battery switch for the start battery and also a BlueSea remote battery switch to combine the house and start battery instead of the fix jumper between both batteries.

Any input, comments and suggestions will be greatly appreciated.

Thanks in advance for the help
Jun 4, 2004
Beneteau Oceanis 352 NYC
I have a 352 and asked sort of the same question. What I do is isolate the starting battery by putting the switch in the off position. This way if the house battery gets drained, I have a way to start my engine and recharge. Every few weeks, I switch the charging by flipping the house off an starter on. Of course this is not ideal and you have to remember to flip the switches all the time. One suggestion was to switch the starter battery off and use and echo charger from the house to starter, thereby, using the house battery to charge the starter battery when needed.

My original goal was to avoid all this "switching" by pulling the starter battery off the house circuit while still maintaining the ability to charge both batteries from the alternator and shore power.
Nov 23, 2009
Beneteau Oceanis 361 Clipper --
I am afraid that the alternator might not charge the house battery completly.
OK, let me first say that I am faaaaaaar from expert on these things.
My boat has a simple splitter of the output from the alternator so that current goes to each battery "side" (engine and services) but not to each other (from engine battery to services and vice versa). When the engine is on I can see that my two voltmeters give around 14V which I guess both batteries get charged.
I have also installed a simple battery monitor (NASA BM1) in the services side and can again see that when the engine is on, depending how full or empty the batteries are, high or low amperes go into the services batteries. So, nothing really complicated is included in my set up and it seems to work fine (hopefully!).
Ah, let me say though (don't know if it is relevant) that the two batteries sides are completely separated, no matter if both red switches are on. If for any reason I need the services batteries to start the engine then I have an extra switch connecting everything in parallel.
By the way I have 2X100amp batteries for services and 1X70amp for the engine.
Jan 22, 2008
Beneteau 323 Annapolis MD
Georges, it is not mentioned if you also charge when on shore power? Yeah, as Joker points out, this same question comes up 3 or 4 time a year. Beneteaus have, what some of us consider, is the best battery setup whith the individual switches. I added a third battery (another house battery) and a third switch. What would someone do if one of two paralleled house batteries dies- go in with tools to work on the cables and try to determine which battery is dead. It would probably have drawn down the good battery anyway. Easier to just throw a switch and isolate each battery.

It is amazing that people will spend the money for an ACR or an antique diode-splitter when they already have a way to combine or separate the batteries via the switches.

I realize everyone's routine is not the same as mine. At the dock I start the engine on whichever battery is on. Once out sailing, and the engine off, switch to the other battery for house needs, and it will charge during your return motor to the slip. In effect, both batteries are used(alternately) to start, and both are used alternately as house. Only one time to operate the switches is needed, which I don't feel is "fipping switches all the time".

There are those who "save" the engine battery for backup, but I wonder if they never use it, will it work when they have an emergency?


Mar 16, 2010
Beneteau 411 Oceanis Annapolis
Check your wiring diagram, my switches only control SUPPLY. The alternator charges both batteries regardless of switch position. Same with the shore-power battery charger.
Feb 26, 2007
Beneteau 361 Quebec
Hi, Thanks very much for the helpful information. Yes, when I am at the dock I charge my batteries from the battery charger (20Ah) that was installed by Beneteau.

The start battery does not get discharge much since I only use to start the engine but it still needs to get it charged by the alternator. My concern is that when both switches are on (combining house and start) the battery that as a higher charge will discharge in the other one and the alternator will charge them both from that point on. If that is not the case then how does the alternator decide that the house battery bank is full?
Thanks very much for the help.
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