Leaving shore power connected

Feb 6, 2013
437
Hunter 31 Deale, MD
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.
 
Feb 26, 2004
22,760
Catalina 34 224 Maple Bay, BC, Canada
Harm? If the power is off, nothing "should" be happening. If that's the case, why bother. If you are constantly charging your batteries on float for the week that you're not there, then there is the probability of sulphating your batteries.

Batteries like to be fully charged before they are disconnected.

It's really a tradeoff, but if you can plug in when you get back to your slip, and charge them up, there's no reason to leave them plugged in all week on float.

As a habit, I almost never leave our boat plugged while I'm not there.
 
Dec 2, 1999
15,184
Hunter Vision-36 Rio Vista, CA.
We have always left our boat plugged in. We leave food/drinks in the refrigerator. I like to have a cold one after my 3 hr. drive to the marina.

On our H'31 we got about 10+ years out of our Gel cells by leaving them on the charger when we are absent.

I guess that leaves you with one Yea and one Nay. (50/50)
 
Aug 8, 2006
340
Catalina 34 Naples FL
My boat is in the back yard in a canal and always plugged in. Refrig is always on too, many times in the summer i leave the ac on when it gets very hot. So some ac some dc.
 
Jan 12, 2012
83
None None Bellingham, WA
I'm guessing you'll get varying opinions on this one. We leave our 340 plugged in all the time at the dock for some of the same reasons already listed above (keep the beer cold, etc.). The PO did the same. The batteries are 8 years old now and though I'm sure they are in their "twightlight years", it wouldn't seem that leaving the boat plugged in has had a significant negative impact on thier lifespan.

YMMV
 
May 6, 2012
303
Hunter 28.5 Jordan, ON
I leave the shore power connected, leaving the main and reefer circuit breakers on.

Everything else is turned off, including the batteries charger.

I too like cold bevvies and calm batteries after the 10 minute commute to the boat.
 
Feb 26, 2004
22,760
Catalina 34 224 Maple Bay, BC, Canada
Wow, varying "commutes" to the boat: 3 hours, 10 minutes and backyard!

Leaving the fridge running is a philosophical and practical issue. Boat fridges are not like the one at home, so I figure if I want a cold one, either I stop at 7-11 on the way, or just turn it one when I get there, only takes a half an hour to cool my box down. Or be British and drink warm beer. :)

Our fridge is 27 years old and still working. I guess there are skippers with fridges just as old that have been running all that time, too.

Your boat, your choice. No one "right" or "better way to do it."
 

Gunni

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Mar 16, 2010
5,937
Beneteau 411 Oceanis Annapolis
Yep, plugged in and battery charging keepin' her ready for launch! Ice-cold refrigerator, and batteries topped for engine-less bliss. I did add a galvanic isolator as a first item because apparently all my dock neighbors can generate a metric-ton of stray current. They were using my zinc without authorization. That has been curtailed. You should consider doing the same.
 
Dec 2, 1999
15,184
Hunter Vision-36 Rio Vista, CA.
Stu: One big advantage of driving 3 hrs is that I do not need to work around the house on the weekend. I get to spend my time working around the boat (or sailing).:naughty::):dance:
 
Sep 20, 2006
2,912
Hunter 33 Georgian Bay, Ontario, Canada
Another vote for plugged in, beer in fridge and running, 2 hour commute and like the boat ready to go as soon as we get there. Only stay at the dock if we have to, otherwise we're out there 1 or 2 nights each weekend.

Any harm? We're on our 8th season with no ill affects. I'd say 90% in our marina stay plugged in all week.
 
Jun 21, 2007
2,105
Hunter Cherubini 36_80-82 Sausalito / San Francisco Bay
IH82BL8 in his opening post mentioned lack of isolation devices. So seems that he may be questioning other issues besides just recharging the batteries.

IH82BL8, if when you leave the boat you generally turn the A/B/Both/Off switch to off, and your don't deep drain your batteries on a typical outing, and that you are mainly concerned about re-charging/maintaining the batteries while you are away for say until the next weekend, and you don't want to worry too much about stray currents from other boats in your marina eating away at your zincs when you are plugged into AC 24/7, then maybe think about installing a smallish (say 50w) solar panel and a latest generation charge controller. Last month's Sail magazine has a DIY article about such a solar installation... that also provided enough daily juice to keep the beer cold. And this forum has many threads with excellent info on the topic.

Stu Jackson (the first respondent to your opening post) comments that he almost never plugs his boat in. I am not nearly in his league with expertise in boat electrics, but that has been my approach as well. My small 20w panel (but I am thinking to increase to 50-60W now that solar panel prices has fallen so much over the last several years), easily recharges my bank within a day of a typical day-sail. Although my demand is typically slight -- only the standard instruments, chart plotter and auto-pilot. And if I am on my boat in the berth for say an afternoon, the 20 watt panel keeps up with the drain from my stereo. In seven years at my berth, total AC billed to me by the marina has been 1kw = about $0.17. Only AC used is for watching DVD's making coffee for the occasional over-nighter, and power-tools needed for repairs. So no need to "AC" except for special instances.
 

Paul F

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Jun 3, 2004
827
Hunter 1980 - 33 Bradenton
Last year leaving the boat in the slip for three months while on vacation, an inexpensive trickle charger was purchased under $20. Also have a shore cord that was split years ago to enable connection to a generator. This cord has a receptacle & plug installed to bridge the split. Anyway this set-up, trickle charger plugged into the shore cord worked so well that it is what is used all the time now. No connection to the A/C electrical system, only the trickle charger is plugged in.
 

kito

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Sep 13, 2012
2,011
1979 Hunter Cherubini 30 Clemmons
I thought that was one of the main reasons to have shore power, to keep your batteries charged and frig running while I'm not there. I hate the thought of having my auto bilge pump hooked to a possible dead battery. Everything else is off except one dedicated outlet for charger and fridge.
 

higgs

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Aug 24, 2005
3,627
Nassau 34 Olcott, NY
Kito brings up the point that I think is critical re the bilge pump. As long as you have a smart charger that won't overcharge your batteries, I see no reason not to stay plugged in.
 
Feb 10, 2004
3,919
Hunter 40.5 Warwick, RI
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.
 
Sep 26, 2008
566
- - Noank CT.
OK just my two cents here but another 24/7 plugged in and even when it is the dog days of summer I leave the a/c on in "humidity control mode". Leave refrig/freezer and ice maker on all the time also. Just a p.i.a to bring everything to the boat and remove it every week just to bring it back again next week. It has an isolator. I also leave the smart charger on all the time. If I go away fore extended time periods I do shut off breaker to unneeded circuits. I guess maybe the bigger the boat the more people leave it plugged in all the time, after all what would a live aboard do ? At some point it just becomes impractical to unplug depending on usage and accessories. Think about the larger sailboats and larger sport fish boats with two 30 amp connection or even the two 50 amp connection. I stay plugged in unless going off the dock.
 
Dec 1, 1999
2,391
Hunter 28.5 Chesapeake Bay
I'm with Rich: I have had concerns about poorly grounded shore power posts at my marina. (Herriington North). One year I stayed plugged in my two shaft anodes got eaten in 2 months. The next year I stayed unplugged other than when I was at the marina. Anodes lasted the whole season.
 
May 24, 2004
7,129
CC 30 South Florida
Test your electrical system periodically and if satisfied it is in good order I do not see a reason why you cannot keep it plugged in 24/7. It is not good to keep your batteries on the charger 24/7 but it all depends how far away you are from the boat. If you have the opportunity turn it off for a couple of days and then turn it back on for a couple more. Some like to leave cabin lights on and a refrigerator on and that is fine. I do turn off the 12V circuits as nothing needs to be operating while docked. The bilge pump is hard wired.
 
Sep 28, 2008
922
Canadian Sailcraft CS27 Victoria B.C.
Depends on the charger. Some, like the Xantrex TrueCharge2, are adjustable to a mode where the charger goes into a rest mode when the batteries are fully charged and doesn't come back on until the voltage drops to 12.5. This is better than a constant float voltage I think.
 

Joe

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Jun 1, 2004
7,999
Catalina 27 Mission Bay, San Diego
When I leave the boat... Shore power is left on...hard wired smart charger always on... DC A-B switches are turned to "off". Don't have an electric refrigerator.. I just like charged batteries.