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Old 19-05-2008, 12:15   #1
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shore power

I have not got shore power arrangement in my boat as yet. My only real drain on battery power is a smallish cool box and a few lights at night. Would it be silly to consider a 12v step down transformer to power these items directly from the shore power rather than the usual battery charger route. Hope this is not a daft question.
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Old 19-05-2008, 12:20   #2
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A battery charger is a step down transformer and will probably cost you less
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Old 19-05-2008, 17:21   #3
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A cheap "dumb" battery charger, with 2-6 or 2-10 amp rates probably will cost you $20 new, ten used. The newer chargers are sometimes too smart--they won't charge a badly drained battery until you bring it partly up with something else first!

So, while you can use any 14.4V transformer (12 isn't quite enough) I'd also say a real battery charger, a cheap one with indicator lights for reverse polarity and jumper cables already on it, is worth the couple of extra bucks it might (or might not) cost.
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Old 19-05-2008, 18:08   #4
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Well, I'll have to disagree with HS. Cheap battery chargers are worse than throwing your money away because you end up throwing your batteries away as well. Cheap battery chargers are not inexpensive on a boat.
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Old 20-05-2008, 11:59   #5
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DeepFrz, you're not disagreeing, you're just missing the focus.

All I've said is that a cheap charger beats kludging a 12v transformer. I'll stand by that.

And if all a battery needs is a weekly or bi-weekly light charge? The manual charger, left on a 2A setting for the right time, can do very nicely. Not as well as a $150 charger--but well enough for one smaller battery with occassional use, IF used properly. But that's a whole other issue. And a whole other price range. Sometimes, "make do" beats "Break Out Another Thousand". Or hundred.[g]
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Old 20-05-2008, 12:37   #6
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get yourself a small freedom inverter and you have the best of both worlds. 600.00 and worth the money IMHO.
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Old 20-05-2008, 12:48   #7
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Thanks for replies. I have just been quoted £100 - $200 for a smart charger. I have read that a cheap car charger should not be used on a boat. I have a steel boat and am worried about galvanic corrosion - will I need an isolator and also a blocking switch in case the engine is started whilst the charger is still on. The bills are mounting. I can buy a 12v step down transformer rated 60 watts for $20, the type 12v garden lights run on. If this would do 240 v electric would not really be in the boat if you see what I mean. Sorry to be so niave about this. I want to keep my power solutions as simple and cheap as possible
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Old 20-05-2008, 13:25   #8
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A “12v step down transformer rated 60 watts for $20, the type 12v garden lights run on” will not be an Isolated Xfmr - which you definitely want.
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Old 20-05-2008, 13:50   #9
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Surely all of you know that a transformer puts out ac voltage and is not suitable for all 12 Vdc loads. A battery charger is not just a 12 volt transformer. You all know that, right? Everybody knows all this stuff; don't you?
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