Electrics

[drpetey]

Hi. I'm in the process of buying a cat to live on for the foreseeable future and I need some advise on battery power as I know bugger all about electrics. It's a crowther 36 and it has 440 watts of solar, no wind but the engine has a hundred watt alternator. The couple that own it have lived on board for thirteen years but at a marina using shore power but I'll be on a pile mooring. It has a TV (marine lcd) and set top box but he said they don't run well off the batteries (4 X 6 volt deep cycle house batteries [2 banks of two]). Now It has a good built in fridge/freezer but apart from that and lights, there's not much to draw power.So why won't the tv run well? This is important as if I'm going to live on it there are only a couple of things I need and TV is one of them (it raised me). I know I can get a little generator but then there's noise and fuel and blah blah. If I swapped out the batteries with deep cycle 105amp or better 12V batteries, would that fix the problem? Or should I add another bank of 2 X 6 volts? There's plenty of room for either of these options. Any thoughts or ideas would be appreciated.
Peter

[Sailmonkey]

It could be that the TV doesn't like the power from a modified sine inverter. Does it run off of an inverter or straight from the 12Volt.

[drpetey]

No it runs off the 12v not though the inverter (which would probably be worse anyway coz it's an old square wave inverter not a sine wave. I'll be rectifying that situation soon). Something about current fluctuation making it flicker and drop out.
Thanks

[Sailmonkey]

could be any number of things ranging from old tired batteries to insufficent gauge wire to the tv or a bad ground somewhere in the system.
replacing the 6v with 12v won't help unless the batteries are old. The batteries you suggested in the configuration on the boat would give you approx 400Ah, the typical 6volt battery is 200Ah (two banks would also be 400Ah)

[drpetey]

So 400amp hours should be plenty to run a lcd tv and set top box for a few hours a night then shouldn't it? He said the batteries weren't that old. I was thinking about just adding two more 6 volts on the same circuit as the others but then I was told that they always revert to the lowest common demoninator anyway and like a chain it's only as strong as it's weakest link. What about a dedicated 12v deep cycle JUST for the TV and set top box running off another solar panel? Like I said, I know bugger all about this stuff so I'm just thinking aloud and if it's a stupid idea allow me to appologize in advance.

[Sailmonkey]

you could do that, but there's no reason it shouldn't work off of the existing batteries. I'd focus my energy first on finding out what causes the tv to blink out. I'd start with voltage drops caused by insufficently sized wires or dirty connections.

I should say that "not that old" really means nothing. If the batteries were abused they could be shot in a few months, or "not that old" could mean 5 years since his last set lasted 7 years.

[drpetey]

That's an excellent point. I look further into it. I haven't taken possession yet but when I do (survey and sea trials on Thursday permiting) it's the first thing I'll be doing. I suspect it will breeze through survey as it's really been looked after and my best friend (a boatbuilder) had a look and gave it the thumbs up (and he's annoyingly pedantic). If you'd like a look goto Boats for Sale - Yachts for Sale - Used & New Boats @ Yacht Hub Australia & New Zealand and then boats for sale, used boats, catamarans 36-40ft and it's the Crowther 7th down on the list.
Thanks again

[Sailmonkey]

Looks fast!! Good luck.

[osirissail]

Look carefully at the existing wiring - behind the walls. It is common in older boats for the previous owner to have made numerous "convenience" hook-ups and bypasses fixing problems rather than really doing it the right way.
- - I have never had any luck with 12VDC TV's and they seem to cost more than buying a discount store LCD TV/Monitor plus a small inverter to supply it 120VAC off the batteries. Then you can play DVD's on your computer and watch them on the "big" screen.
- - I hope your meant 100 "amp" alternator and not 100 "watt" alternator. There is a world of difference.