In article ,
Wayne.B wrote:

Which pretty well summarizes most of the advice that others have
offered:

- a single 100 Amp-Hour battery is not big enough because: 1) It will
not supply enough power to be useful; and 2) It will not accept
recharge current at a high enough rate to recharge quickly.

I forget the original post, but though we have two 120 AH batteries,
I've been using only one for a couple of seasons. Started as a test of
our 12w solar panel, but I've come to like the system. Our major
consumption is the anchor light, VHF and interior lights. No fridge. I
discount the stereo, autopilot and such as they're small or infrequent
loads.

If it's partly sunny most of the day, the solar cell is sufficient. If
we happen to run the battery flat, a couple of hours' sunlight will
bring us up far enough to start the Yanmar.

--
Jere Lull
Xan-a-Deux ('73 Tanzer 28 #4 out of Tolchester, MD)
Xan's Pages: http://members.dca.net/jerelull/X-Main.html
Our BVI FAQs (290+ pics) http://homepage.mac.com/jerelull/BVI/

On Fri, 29 Dec 2006 09:21:11 GMT, Jere Lull wrote:

snip
If it's partly sunny most of the day, the solar cell is sufficient. If
we happen to run the battery flat, a couple of hours' sunlight will
bring us up far enough to start the Yanmar.

So what do you do if you suddenly need the engine on a foggy day!!!!!

I cannot see any sense in a setup like this.



Richard

Nb "Pound Eater" Parkend G+S

On Fri, 29 Dec 2006 09:21:11 GMT, Jere Lull wrote:

If it's partly sunny most of the day, the solar cell is sufficient. If
we happen to run the battery flat, a couple of hours' sunlight will
bring us up far enough to start the Yanmar.

Running the battery flat is not conducive to good battery life and
should be avoided if at all possible with some sort of monitoring
device (other than dimming lights). An inexpensive digital volt meter
is sufficient - at 11.6 volts under load, it is time to recharge.

"Electricky Dicky" wrote in message
...
On Fri, 29 Dec 2006 09:21:11 GMT, Jere Lull wrote:

snip
If it's partly sunny most of the day, the solar cell is sufficient. If
we happen to run the battery flat, a couple of hours' sunlight will
bring us up far enough to start the Yanmar.

So what do you do if you suddenly need the engine on a foggy day!!!!!

I cannot see any sense in a setup like this.



Richard

Nb "Pound Eater" Parkend G+S


You wait. Actually, a bit of fog should still let allow some charging...
certainly true for our home solar panels.

--
"j" ganz @@
www.sailnow.com

In article ,
Electricky Dicky wrote:

On Fri, 29 Dec 2006 09:21:11 GMT, Jere Lull wrote:

snip
If it's partly sunny most of the day, the solar cell is sufficient. If
we happen to run the battery flat, a couple of hours' sunlight will
bring us up far enough to start the Yanmar.

So what do you do if you suddenly need the engine on a foggy day!!!!!

I cannot see any sense in a setup like this.

As I said, it was a test. In practice, we don't run the battery down
that far, and we *can* charge when it's foggy or partly overcast.

AND we do have a fully-charged second battery.

My next iteration on the system will be a group 31 directly connected to
the engine with minimum-length leads, the house bank considerably larger
and usually disconnected from the starting battery and alternator, but
hard-wired to the solar.

--
Jere Lull
Xan-a-Deux ('73 Tanzer 28 #4 out of Tolchester, MD)
Xan's Pages: http://members.dca.net/jerelull/X-Main.html
Our BVI FAQs (290+ pics) http://homepage.mac.com/jerelull/BVI/

Shaun Van Poecke inscribed in red ink for all to know:
I'd be really interested to know how much power peopleare using on their
boats. It neednt be too exact, though it would be nice if you had some real
Ah figures, but just generally what size of battery bank you have, what you
use on a daily basis in terms of power, and how often/how long you need to
charge for.


Im about to fit out a thunderbird 26 for cruising and its really tough to
figure out how much power and how much charging im going to need. What im
thinking is probably a single 100Ah AGM battery, a 2000watt generator hooked
up to a 30A charger. I dont really have a lot of power needs, just lighting
(flourescent), a cd player that gets used a couple of hours a day, Nav
lights, and power for my GPS/notebook as needed.

Im hoping to get 2 to 3 days use without charging.

Shaun




In the Pacific NW:

Refrigeration: 60-90 ah/day
anchor light: 16 ah/day
inverter loads: 50 ah/day

bob

On Tue, 02 Jan 2007 10:12:05 -0800, RW Salnick
wrote:

In the Pacific NW:

Refrigeration: 60-90 ah/day
anchor light: 16 ah/day
inverter loads: 50 ah/day

That jibes very closely witn my experience in the North East. In the
south refrigeration takes a bit more, probably more like 120 A-H/day.

Wayne.B wrote:
On Tue, 02 Jan 2007 10:12:05 -0800, RW Salnick
wrote:

In the Pacific NW:

Refrigeration: 60-90 ah/day
anchor light: 16 ah/day
inverter loads: 50 ah/day

That jibes very closely witn my experience in the North East. In the
south refrigeration takes a bit more, probably more like 120 A-H/day.

Same as mine, though with my big freezer I don't see 60 AH from the
fridge, its more like 70-110. Also, my inverter loads are lower
because I try to use as many 12V appliances as I can. In particular,
I found that the AC/DC TV uses a lot more power in AC mode. TV, DVD,
FM, cell phones, etc all run off DC. The computer is the only thing
that uses the inverter, and that only about an hour a day. Other AC
loads, like the occasional microwave and coffee grinder are only a
minute or so and don't add up to much. In fact, the big inverter is
left off almost all the time and only turned on for special needs.

But the totals aren't much different - around 120 to 170 a day, with
around 30-40 recovered with solar and the rest either engine run or
the small Honda gennie.

purple_stars wrote:
All that said, yes, I ran an electrical system with nav lights, laptop,
handheld radio, handheld gps, etc, using a Honda EU1000i generator for
about a month and it worked fine. But I had to run that generator a
lot mostly because I had a very small battery bank and was using a
charger from an automobile parts store. If I would have had a charger
big enough to use all the amps the generator was capable of and a
battery bank big enough to absorb them all it would have been a good
system, but as it was it was a lot of trouble and I always spent a day
or two doing nothing but charging up devices and batteries before I
made any passage anywhere.

I regularly charge with a Honda EU1000 generator (to avoid the noise
and stink of running the engine) and found that a Lewco 40amp charger
pretty much loaded the generator to its rated 800 watt continuous duty
rating when the batteries were low. That's not a lot of charging
power, 40 amps being appropriate for about a 100 to 200ah battery bank.

Yea, 800 watts @ 12.5volts should be more like 65 amps, but transformer
based chargers are notoriously inefficient, note how hot they get when
at rated load. Although newer switching type chargers are claiming
efficiencies of about 80%, which would be more like 50 amps using an
EU1000.

On 3 Jan 2007 21:09:59 -0800, "Mark" wrote:

Yea, 800 watts @ 12.5volts should be more like 65 amps

Don't forget that actual charging voltage is more like 14.2 volts
which equates to 568 watts with no adjustment for losses or power
factor.

Assuming 90% efficiency and 90% power factor (inductive load), you
would need something like 700+ watts from your generator.