Third Battery

My Californian has the standard two batteries. Both are on a power switch and are Batt's 1 & 2. Both are relatively new. Interestingly, there is a third new battery that is sitting near the main batteries. Should I install parallel cables to one of the main batteries to maintain a charge in this spare battery and to keep it fresh and in good condition?

ON 1 or 2 are both house and start loads on the selected batt?

Sam said:

Interestingly, there is a third new battery that is sitting near the main batteries.

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Whats this third battery connected to? How does it get charged? Is it just sitting there with nothing connected to it? 6v or 12v? If 12v why not connect it in parallel to your house bank.

You should probably not, unless they are the same brand and model and are the same age. Otherwise, the older one will drain the newer one and eventually ruin it (batteries in parallel are a bit like a chain, as strong as the weakest link).

A good solution for your setup would be to get what is called an echo charger (by xantrex, about $75 I think). You hook it up to one of your batteries that is getting a charge from your alternator or charger and to your 3rd battery. The device detects when your battery is being charged and sends some juice to your 3rd batt until it is also charged. Works like a charm in my boat to charge my start battery. So while you're at it you could use that battery as a start battery, that way you are sure the engine will always crank even if the house banks are dead.

If that 3rd battery is not part of you system and you just want to keep it charged and ready in case you need it for an emergency, then just an occasional charge (once every month or so) with any battery charger will do just fine.

Thank you all. All of the batts are new, as the PO had just purchased prior to my ownership. Given that they are new, I will hook up batt in parrallel with house batt, which already have shore power charger. I am learning little by little. ie: house batt/starter batt.

Here is a another question then. There is a newer charger keeping the batts charged from shore power. In general, I have been keeping the batt switch in the "both" position while at shore or under power. I assume that this is generally accepted unless I am off to timbucktoo and want to assure that I do not use so much house power that the engines will not start. Is this the correct use of the switch/batt?

Sam,

I assume your batteries are connected to the alternators through the 1-ALL-2-OFF switch and the start cables. In this case, it's normal to run in ALL to charge both battery banks. However, you must then remember to switch back to the house bank when you stop. If you leave your banks paralleled in the slip on the shore charger, you tie them together as one battery and you're not helping your battery health.

If you rewire appropriately and install an echo charger or Blue Seas Automatic Charge Relay (ACR) you can leave the switch in the start position, charging both banks and pulling house power only from the house bank while at anchor unless ALL is selected. It takes some re-cabling, but it's a failsafe and foolproof way to prevent unintentionally leaving your banks paralleled or isolated.

I recabled my Californian last spring and have absolutely no regrets. I never have to touch my battery switches for normal operations, but they're there (outside the engine room) if I ever need to isolate or combine the batteries.