shore power with out shore power

[marcusn]

No shore power on my boat.

since I won't be motoring much, I'm thinking I might need to charge the batteries occasionally this summer while in the slip. I was thinking I'd get a 30amp to 15amp adapter to use while I'm hanging out on the boat, and run a standard extension cord (carefully strung away from all water) connected to the portable battery charger I'd have in the cabin.

Does anyone else do this?

I realize the risk, and know that I'd have to be careful x3, and would without doubt, not leave it unwatched, or leave it for more than an hour or two.

[Rockter]

Just stay on the boat when it's powered up, and keep a check on the current it's using.
The charger will not use much current. My olde 275 Ah battery typically demands about 10 ampere DC from the charger, and at (say) 14V, that's about 140 W.
It drops off slowly to about 3 ampere.

Your 110 V AC supply will only have to deliver you with about 1.3 A AC to deliver 10 ampere at 14V.

As a rule, I never leave anything powered up when I am not on the ship.
It might be over-cautious, but it's always made me a bit nervous.

The slightest problem we will see and hear, and we can defend the ship quickly if there is a charger malfunction.

[negrini]

If your battery charger has current limitation (3-5 charging cycles would be even better), some sort of electrical protection (fireproof, polarity, etc), and your wire connection is safe, you're ready to charge your batteries. I used an automotive charger for my 23 feet for many years, never left it unattended (never would sleep on my berth, with that connected), never had a problem. But that was a premium charger and simple flooded batteries.

[merttan]

I kept my boat connected to standard electrical power outlet charging the battery and using my laptop all summer last year... The cable got wet and everything... First things first, make sure there is break switch on the power post, since a main breaker would take longer to shut off in case of, you know the buzz... Keep the extension cable free of any defects like scrathes or kinks... And you should be; though it's not recommended doing so, highly not recommended, ok...
Other than freaked out people, I didn't have any trouble last year... I ain't doing it this year though... Electricity+water=nothing good

[sailingdog]

Of course, people are overlooking three major details.

First, a standard extension cord doesn't LOCK into the outlet—this means that the cord can become separated and possibly an electrocution risk much more easily.

Second, a standard extension cord isn't as well insulated or as heavily waterproofed as a marine shore power cord. That means that if there are any tiny holes or cracks in the insulation, you have a higher chance of breaching it and possibly getting electrocuted.

Third, the extension cord becomes a fire hazard, since the breaker is rated for 30 amps, and the cord is generally rated for only 15 amps.

It is probably a much better and wiser idea to properly install a shore power outlet and main AC panel on the boat, even if it is only hard-wired to a marine-grade three-stage charger.

DON'T USE automotive chargers in a boat that is on the water. They're not designed for the high levels of humidity and salt air. Automotive-type battery chargers are also responsible for a large number of boat fires every year.

If you're going to take the short cut and half-ass this... make sure that the shorepower outlet is GFCI protected and that the GFCI is WORKING. Also, secure the extension cord so that it can not fall in the water or become accidentally separated from either the charger or the pigtail at the shorepower box.

[BarryL]

Hello,

If you are careful you will probably be OK.

How many batteries do you have, where are they located, how heavy are they, etc.? If it's not too much trouble, perhaps you could bring the battery home and charge it there.

Barry

[merttan]

I used a outdoor extension cable... Still weaker than marine grade but holds...
The power post on my marina had regular electric outlets beneath the 30amp oulets...
It's expensive to install that stuff...
I used a 15 year old car/motorcycle charger w/o any problems...
I know I'm crazy...

[Rockter]

Sailingdog...

How much will that lot cost, and how long would that take?

That will take quite a few week-ends to wire that in.

I think he only wants to charge the batteries every now and again.

With the owner on board, an automotive charger really is a reasonable risk. I have done it for years, like three times a season. It buzzes for a few hours, then quietens, and is silent before morning. There is a smoke alarm nearby.

With the chap on board with an automotive charger, for say one night, three times a season, that certainly is a reasonable risk. Surely?

Bring the shore-power lead inside the cabin. Connect the charger to the batteries, then plug it in. Do not, do not, DO NOT put the charger onto the battery or pull the charger leads off the battery if the charger is live. Switch it off first.

I did that once, with a motorcycle battery... there was hydrogen around. Pop-boom !!! It really does make a mess.

Charge the batteries and go sailing there guys.

[SEMIJim]

If one were to use a high-quality outdoor extension cord and secure it well, I see nothing massively wrong with such a lash-up for occasional use.

The thing I'd most question is the use of an automotive charger. I think one would be far better-off looking for a good marine charger when they go on sale. A buddy of mine picked one up last year, off-season, for a song.

That being said...

He's in a slip. He's got a 30A outlet there already. He'd just need to add to his boat the 30A bulkhead connector and wiring to his battery charger. And a fuse or circuit-breaker? (Don't know what the requirements or best practices call for.) One day's work, at most--and that's going slowly. That's what I'd do. Those 30A -> 15A adapters are expensive; a regular extension cord, even a heavy-duty one, still isn't quite a marine-grade shore power cord and, as I noted, a proper intelligent marine battery charger would be far better for his batteries.

There's more to maintaining marine batteries in port than just hooking up a charger and topping them off occasionally. And dead batteries when you're out in the middle of somewhere can be unamusing. I've been there. (Not on my boat, and not under my command, I'll note.) Treat your batteries well and they'll treat you well. Abuse them and they'll repay you in kind.

Jim

[drynoc]

I used to have a Vector smart charger which I hooked up via the extension cord and the adapter method whenever I was on the boat and not going out, and it worked fine. I never left it hooked up when not on the boat, and I have since installed shore power and a hard wired charger, but his idea will work with the proper precautions as mentioned in the other posts.