Leaving shore power connected

[Stu Jackson]

For those of you who leave plugged in all the time; Have you ever been out for an overnight trip and been surprised when your batteries failed?

Seems that keeping a charge on all the time could mask potential battery failures.

 

[Joe]

For those of you who leave plugged in all the time; Have you ever been out for an overnight trip and been surprised when your batteries failed?

Seems that keeping a charge on all the time could mask potential battery failures.

Never has happened to me but I disconnect the 12 volt system when I'm gone. If I had a refrigerator I'd look for a combo 12v/110v appliance.... Let it run directly off the shore power when available.

I use Wal mart or Costco wet cells on a true charge 10 amp smart charger. The batteries will go 36 to 42 mos before they just quit... just like a car. I did the math years ago when I got sticker shock looking at replacements for the worn out 8 year old gels. Even if you get 10 years the numbers favor the wet cells.

 

[Steve L22188]

Maine Sail....where are you?

I leave my shore power plugged in and the charger on - sometimes for 4-5 weeks at a time between sails. Have a 10 year old Xantrex charger that supposedly only does it's recharging thing when it needs to do so. But I've always wondered about this.

Maine Sail....surely you can weigh in on this?

 

[wufibugs]

I branched the shore power wire to a single dedicated plug protected by a circuit breaker for the dorm fridge. When I have things in the fridge I want kept cold or frozen between visits, I leave that plug on but all else is off. I can also opt to have the old Xantrex inverter charger on with everything else off. Also shore power plug at the pedestal at the slip is on a breaker easily flipped as I walk by.

 

[Maine Sail]

Is there any harm in leaving shore power connected as long as the boat is at the dock and leaving the battery charger on? This is overkill for keeping the batteries charged. I don't have an isolation transformer or a galvanic isolator. Should I turn off the AC panel and also unplug from the dock?

Thanks.

If you have no isolation from the rest of the marina consider a small solar panel to keep topped up, or, at a bare minimum, a galvanic isolator if you want to remain plugged in.

Turning off the AC power does not isolate you, if the cord is left plugged in...

 

[IH82BL8]

Thanks, all. Very informative responses as ever.

It sounds like staying plugged in is a matter of convenience and unplugging is a matter of protection. Of the two I will go with the latter.

A little more information for me situation: No refrigeration on board. I am installing air conditioning, but I'm nervous about running it while I'm not on board; if a jellyfish gets sucked into the intake the unit will be damaged. Also, my opinion is that if the batteries drain while everything is turmed off, there's a problem that requires immediate attention.

Warren Milberg's response really got my attention because I'm at the same marina.

 

[kito]

I said earlier that I have no problem leaving my shorepower plugged in but have to admit, the condition of the ac wiring, panel etc. that the previous owner left it in was horrendous. Different gauge and type wires (old solid strand house wiring), outlets corroded and worst of all, wires at the panel were just twisted together and taped off with old, dry brittle tape. I would not power that system up no matter what. I ripped it all out and installed new. I guess my point is, if you trust your boat's ac system and have a galvanic isolator and smart charger, leaving it on shouldn't be an issue.

 

[Gunni]

I am installing air conditioning, but I'm nervous about running it while I'm not on board; if a jellyfish gets sucked into the intake the unit will be damaged. Also, my opinion is that if the batteries drain while everything is turmed off, there's a problem that requires immediate attention.

Warren Milberg's response really got my attention because I'm at the same marina.

If you install a quality A/C it will include a seawater strainer, and protection circuitry that senses a loss of raw-water flow and auto shutdown of the unit. They are very tough devices when properly installed. One of the best things about the better A/C units is their dehumidify-mode that periodically cycles the A/C to dry the boat air. This goes a long way toward keeping your boat mildew free.

Apparently Warren can't afford the $100 it would cost to purchase a galvanic isolator?

 

[Gunni]

I am surprised that nobody has really emphasized the danger of boat-to-boat electrolysis damage due to faulty wiring that could be common in other boats or even on the docks. My sailboat lives on a mooring but if I were on a dock I would think twice before being connected 24/7.

All you need is a transient boat with bad wiring to visit your marina , and you could be at risk.

When I was looking at boats for sale, all the +40ft. hunters had isolation transformers. A step up from the ground isolators.

 

[Stu Jackson]

Apparently Warren can't afford the $100 it would cost to purchase a galvanic isolator?

I did notice your , but IIRC there was a long period when galvanic isolators would NOT show that the diode inside had failed. IIRC, also, that newer models do have this feature. If you have one, or are contemplating buying one, assure yourself that you can tell when it's failed.

 

[Maine Sail]

Apparently Warren can't afford the $100 it would cost to purchase a galvanic isolator?

Problem is that galvanic isolators only protect you from galvanic current, not stray current above galvanic levels.

I am not at a marina, but if I was, the only way I would plug in is with an isolation transformer.

 

[Scott B]

When I was looking at boats for sale, all the +40ft. hunters had isolation transformers. A step up from the ground isolators.

My '05 Hunter 33 has Isolation transformer as does the 31, so this would also include the 36, 38 etc.

 

[Jalepeno]

The ground wire is connected whenever you are “plugged in” and you may still be susceptible to galvanic corrosion even if your main breakers are off.

 

[Tejas]

We have are boat on a fresh water lake, actually a river-fed reservoir. Due to a drought, boats had to be moved from the marina out into the stream. Unplugged from the dock, the battery monitor paradoxically slowly drew down the batteries, so we installed a small solar panel to maintain the batteries.

That was two years ago, and although the boat is back on a dock with power, we have not plugged back in. Being on fresh water, our "zincs" are magnesium, and the annual erosion seems less unplugged from power.

 

[Gary_H]

I unplug from the shore power when I leave the boat. I am afraid of galvanic corrosion. A friend of mine lost his prop in the same marina. My boat is small and I don't have refrigeration. I have two solar panels on charge controllers that have kept my batteries charged without any problems. I have a AC battery charger but I haven't used it since I got the panels. I only plug into shore power when I'm staying on the boat at the slip.

 

[wufibugs]

Maine, what would be the minimum specs for an appropriate isolation transformer?

 

[shemandr]

Don't know much about charging. But with regard to cold beer, which seems to have a lot to do with why we leave our chargers on, if the Brit's lived in a climate like the Southern US they would damn sure drink their beer ice cold.
Seriously, what works for a guy in SF or for a guy in Florida, might be completely different for the reason that they live in completely different climates.

 

[Stu Jackson]

You mean they don't have 7-11s in Florida to get cold beer on the way to the boat?