Looking for advice on having a solar panel keep my batteries topped
up. I have two group 27 dual purpose batteries on Quint, use the boat
on weekends and occasional trips (working stiff, ya know). The
batteries are connected in parallel with the usual 1-2-both-off
switch. The boat is in the NE and will be on a mooring for the first
time and I want to keep the batteries up with a solar panel. I plan
on a flexible panel on the dodger. Any ideas on size, whether I need
a controller and how to connect it (plug into the cigar lighter with
the switch on both or something more permanent)? Your experiences
would be helpful. Thx

In article .com,
"Quint" wrote:

Looking for advice on having a solar panel keep my batteries topped
up. I have two group 27 dual purpose batteries on Quint, use the boat
on weekends and occasional trips (working stiff, ya know). The
batteries are connected in parallel with the usual 1-2-both-off
switch. The boat is in the NE and will be on a mooring for the first
time and I want to keep the batteries up with a solar panel. I plan
on a flexible panel on the dodger. Any ideas on size, whether I need
a controller and how to connect it (plug into the cigar lighter with
the switch on both or something more permanent)? Your experiences
would be helpful. Thx


We have about that setup and schedule: Two 31s and a 12w hard solar cell
that just sits on a bench -- or the bimini while we're out. Hardly ever
switch to the second battery, even when we're out for a couple of weeks.
We ran one battery down once. As a test, I just turned things off to see
what would happen. By at least 11AM, the cell brought it up enough to
start the Yanmar.

No controller needed on that small a cell; they have their own blocking
diode.

--
Jere Lull
Xan-a-Deux ('73 Tanzer 28 #4 out of Tolchester, MD)
Xan's NEW Pages: http://web.mac.com/jerelull/iWeb/Xan/
Our BVI FAQs (290+ pics) http://homepage.mac.com/jerelull/BVI/

On Feb 23, 9:57 am, "Quint" wrote:
. . . Any ideas on size, whether I need
a controller and how to connect it (plug into the cigar lighter with
the switch on both or something more permanent)? Your experiences
would be helpful. Thx

1% of battery capacity in amps is about right for floating, so 2x105a
batteries would be about 2 amps or a 24 watt panel. Bigger, you risk
gassing electrolyte off in the summer; too small, and there's not
enough oomph to keep things topped off in winter. Pluggin' into the
cigar lighter is fine with just a 2 amp load, but the receptacle
should be fused, they usually are fused at 20 amps or so. Directly
connecting to the batteries without a fuse is a no-no, fire hazard.

One thing to watch out for is: disconnecting (switch "off") the
batteries while the panel is plugged in, as the panel can drive your
DC circuitry up to 18 volts or so with just a tiny load present, like
status lights, radio memories, etc., and blow them out.

I've been running 40 watts of panels on 500ah of batteries, and it's
amazing, all the cell's S.G. have stabilized at 1.275 after a few
months of 5ah or less of load each day. Before, I was intermittantly
charging the batteries and the S.G. range when fully charged varied +-
0.010 after a few months, requiring an equalization charge.

I think a float panel on a boat that's intermittantly used is really
kind to the batteries.

In article .com,
"Mark" wrote:

I think a float panel on a boat that's intermittantly used is really
kind to the batteries.

That's the truth. My batteries are much healthier. One that seemed on
its last legs came back nicely.

--
Jere Lull
Xan-a-Deux ('73 Tanzer 28 #4 out of Tolchester, MD)
Xan's NEW Pages: http://web.mac.com/jerelull/iWeb/Xan/
Our BVI FAQs (290+ pics) http://homepage.mac.com/jerelull/BVI/

Jere Lull wrote:
In article .com,
"Mark" wrote:

I think a float panel on a boat that's intermittantly used is really
kind to the batteries.

That's the truth. My batteries are much healthier. One that seemed on
its last legs came back nicely.



Volkswagens are shipped with a small solar panel that plugs into the
cigar lighter. This is used to keep their batteries up during the
journey to the dealer. Dealers remove them as part of dealer prep.

The dealers usually just throw away these panels so mostly they're
available just for the asking.

I had one for my sailboat. Worked great keeping up the two gp 27
batteries. I've also seen them on small charter fishing boats.