Battery switches. On or off?

JamesT

Active Member
Oct 7, 2013
250
Somers Point, NJ
Boat Info
2011 470 Sundancer
Engines
Cummins 480s w/ Zeus PODs
When leaving the boat for a week or two, is it best to shut both battery switches off, but leave the battery charger on? Needless to say I don't need any DC appliances while the boat is not in use. What is recommended protocol and why?

Also, I heard from someone that I should check the fluid level in my batteries once per week. I've never done this before, 7 years of boating. Anyone have more insight on this?
 
I turn mine off when I leave the boat... there are varying opinions on this. We do not have shore power at our slips.

I top my batteries off twice a year... at winterization and at de-winterization. Where I store, I can leave it plugged in and the charger on.
 
Off.... Because my mech said so. Anything that needs a memory voltage hookup has bypassed the switches. Any safety gear (bilge pumps etc..) are direct wired. If it weren't for the need for AC dehumidification and fridge, I'd shut the whole thing down and go home.

As for the batteries, they should be checked at least monthly. They get more of a workout than a car battery. Of course most boat batteries are not in an area condusive for checking them. You may want to consider a golf cart battery watering system. It makes the whole job a LOT easier.
 
James,

We use the boat on most weekends all 12 months and we have shore power. I never turn off the battery switches, I just turn off specific circuits. During spring and fall, most everything is off except fridges and icemaker. In summer we add AC for dehumidification and winter add heat as required (50°F).

Chargers are always on. With six 8D batteries, I check 3-4 times a year and add distilled water as need. Definitely not an expert on the battery subject. Weekly, in the old days of crappy chargers....absolutely. But it seems excessive to me now that chargers are smarter. Based on your climate and conditions you will probably modify this as needed for your equipment.
 
I leave my port bank switch on since both refrigerators (cockpit and cabin) are powered from that bank, and turn the starboard bank switch off (although I have forgotten and left it on in the past with no concern or consequence). Accordingly, I leave the DC breaker on for the refrigerators. On the AC side I leave the converter breaker on to keep the batteries charged and also the refrigerator AC breaker on. We do have shore power at our slip. If the AC power goes out then the refrigerators stay cold on battery power until the power returns.

If shore power is available, my philosophy is to always keep the AC converter on in case of a leak of some kind that bilge pumps can keep up with and keep the boat afloat until someone notices, which may be longer than the batteries would hold out.

I check the battery fluids in the spring, sometimes mid-summer, and usually in the fall before winterization. They almost never need any fluid.
 
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mine are ON all the time plugged to shore power with smart charger
 
I trust Jim to the end of the dock. But....I turn mine off. I let the shore power handle stuff while I'm not there. I am a bad enough sleeper without battery switch worries keeping me awake!


Mark
 
I've never turned off a battery switch, and I don't really understand why you would.

Don

I agree. I never turn off the batteries. I do turn off the breakers to all electronics, house water pump, one of the 2 water heaters, anything that doesn't need to be on.
 
Switches on, connected to shore power, unnecessary items off. Check batteries beginning of season, mid-season, prior to hibernation.
 
Most chargers are "smart" chargers and will only run when the battery calls for charging. In my opinion, the critical need for a charged battery while away from the boat is the bilge pumps. If the pump(s), which are straight wired to the batteries, had to run, the batteries would call for charging. Without the charger on, how long could you ask the battery to pump water - an answer I don't want to have to find out.
 
On shore power, A/C Converter switch ON...will the batteries still charge if the battery switch is set to off?
 

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