On Tue, 21 Sep 2010 08:32:18 +0700, Bruce in Bangkok
wrote:

On Mon, 20 Sep 2010 08:10:32 -0500, CaveLamb
wrote:


But a small generator would do it.

Know of any small 12 volt only gen sets?
(I think the manufacturers are missing a niche here)

I don't know about back there but they are fairly common here. I think
that most of them are actually 220 VAC generators with a rectified
circuit but they do charge batteries.

There are scads of those kind on the market.
But even the small ones are pretty fair sized - and pricey.
There is no real technical reason one couldn't make a 12 volt gas powered
charger no bigger than a weed-whacker motor.
(BTW, the 4 stroke versions are pretty quiet)


You can. But remember, there ain't no free lunch. I saw a mini-gen set
when I was in Vietnam. You could hold it in one hand, probably a 1
cu.in. engine driving a tiny alternator. It would just about power one
100 watt light bulb.But a 2.5 - 3.0 HP engine will drive about a 2 KW
alternator/Generator which would be over one hundred amps at 13.5
volts DC..

Google on Home Built Generator for a lot of ideas and examples. BUT
you have an air cooled, gasoline engine and they are a pain in the
butt. They are noisy, they take exotic fuel (at least exotic to 'in
board motor" people:-) and they get damned hot; the exhaust is hot
enough to ruin your gelcoat. But certainly you can build one with
minimum investment.

In fact that is exactly what I used for two years on anchor in
Singapore. I used to fill the tank; pull the rope; check the volt
meter and ignore it the rest of the day. Eventually it would run out
of gas and by that time I had enough battery charge to last another
day.



If you got a spare quid you might look into solar panels. I somehow
get the impression that most of your sailing is a week-end sort of
thing and a solar panel, or two, would certainly keep your batteries
charged.... as long as the sun shines.

That's true for now.
The marina has AC power, so keeping batteries topped off is no problem.
But a couple of days out of the marina gets to be a challenge.

I've converted most of the lights to LEDs.

The real current hogs are the pumps.
Like the pressure water system and wash down pump.

I have a couple of solar panels - 5 and 15 watts.
But I'm not quite sure how to work them with the existing battery charger.



Cheers,

Bruce
(bruceinbangkokatgmaildotcom)

You can buy 1, 2, etc., watt inverters here pretty cheaply. Of course
they are Chinese made and vary in quality, and efficiency, but still
pretty good bang for the buck.

The solar panels connect to the batteries. There are a number of
Gotchas though.

You need to be sure that the solar panels have a diode incorporated in
them to prevent reverse current flow. If yours are fairly recent they
likely do but still, take the time to check them.

Unless your panels are extremely small it is possible, if left
connected, for them to boil your batteries and you'll come back to the
boat after a month away and find the batteries dry.... and require
replacing. The answer is install a Solar Panel Regulator. Reasonable
in price and effective. Another method is to simply cover the solar
panels with a dark cover - black garbage bags will work. Of course if
you do then nothing keeps the batteries charged :-(

If I had a boat like yours (I am assuming that you don't have a shower
in the Head) I'd have foot operated water pumps. Believe it or not but
they do save on water use - you really use only what you need.

A wash down pump is really a luxury :-) I hade one rigged to wash down
the anchor but since I also had a power anchor windlass I always
hauled the anchor with the diesel running so a little extra current
for the pump was of little interest.

Cheers,

Bruce
(bruceinbangkokatgmaildotcom)
Cheers,

Bruce
(bruceinbangkokatgmaildotcom)