In article 2cfAg.306263$iF6.139599@pd7tw2no,
Gary wrote:

The panel I have is a 46 watt panel and I will be running it into two
100 amp batteries. It produces a maximum voltage of 14.6 and maximum
of 3.6 amps. I was wondering just how self regulating it would be.
Do you leave yours on all the time?

Ours is on full time. All indications are that it isn't overcharging
the 120 AH battery.

I no longer parallel even "identical" batteries for any length of time.
If one of them is slightly weaker, it will likely go south.

My preference would be to install an 8D or a couple of big 6v in series.
Doubt that panel would hurt either of those.

Of course, I'm talking without knowing anything about the
self-regulation. If it actively limits the current at high voltage,
you're safe. If it simply has a diode to keep from draining the battery
at night (like ours), you are less protected, though a max of about 50
watts is easily dissipated.

BTW, expect your panel to perform better than the numbers, as they rate
for what they expect after a few years' service.

As I think, with a max 15 volts, you probably have active regulation,
since modern cells are designed to charge even when slightly shaded.

Keep track of things for a bit. If you have to add water quickly, your
panel is too big for the battery, so get a bigger battery. It's tough to
have too many AH.

--
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/

Jere Lull wrote:
In article 2cfAg.306263$iF6.139599@pd7tw2no,
Gary wrote:


The panel I have is a 46 watt panel and I will be running it into two
100 amp batteries. It produces a maximum voltage of 14.6 and maximum
of 3.6 amps. I was wondering just how self regulating it would be.
Do you leave yours on all the time?


Ours is on full time. All indications are that it isn't overcharging
the 120 AH battery.

I no longer parallel even "identical" batteries for any length of time.
If one of them is slightly weaker, it will likely go south.

My preference would be to install an 8D or a couple of big 6v in series.
Doubt that panel would hurt either of those.

Of course, I'm talking without knowing anything about the
self-regulation. If it actively limits the current at high voltage,
you're safe. If it simply has a diode to keep from draining the battery
at night (like ours), you are less protected, though a max of about 50
watts is easily dissipated.

BTW, expect your panel to perform better than the numbers, as they rate
for what they expect after a few years' service.

As I think, with a max 15 volts, you probably have active regulation,
since modern cells are designed to charge even when slightly shaded.

Keep track of things for a bit. If you have to add water quickly, your
panel is too big for the battery, so get a bigger battery. It's tough to
have too many AH.

Thanks. I'll just wire it up and watch for a while. Too easy!

Jere Lull wrote in news:jerelull-94DCFA.21000703082006
@news.verizon.net:

In article 2cfAg.306263$iF6.139599@pd7tw2no,
Gary wrote:

The panel I have is a 46 watt panel and I will be running it into two
100 amp batteries. It produces a maximum voltage of 14.6 and maximum
of 3.6 amps. I was wondering just how self regulating it would be.
Do you leave yours on all the time?

Ours is on full time. All indications are that it isn't overcharging
the 120 AH battery.

I no longer parallel even "identical" batteries for any length of time.
If one of them is slightly weaker, it will likely go south.

My preference would be to install an 8D or a couple of big 6v in series.
Doubt that panel would hurt either of those.

Of course, I'm talking without knowing anything about the
self-regulation. If it actively limits the current at high voltage,
you're safe. If it simply has a diode to keep from draining the battery
at night (like ours), you are less protected, though a max of about 50
watts is easily dissipated.

BTW, expect your panel to perform better than the numbers, as they rate
for what they expect after a few years' service.

As I think, with a max 15 volts, you probably have active regulation,
since modern cells are designed to charge even when slightly shaded.

Keep track of things for a bit. If you have to add water quickly, your
panel is too big for the battery, so get a bigger battery. It's tough to
have too many AH.


I always hate that...along with having too much money! :-)

-- Geoff

My common knowledge, experience from other cruisers and other research
differs from the below:

GBM wrote:
"Glenn Ashmore" wrote
First of all 150 watts of panels is not going to produce 430 AH. You
would
be very lucky to get 300 or so. If you can produce 56 AH/day extra just
leave the refrigerator running and have the cold beer ready and waiting
for
next weekend. A half way decent refrigeration system should keep cold
without being opened on 50 AH a day.

You are right Glenn - 150 watt panels will probably not produce 430 AH. But,
according to this link it should have been about 405 AH:

http://www.qsl.net/ve3lgs/solarpnl.htm


Everything I've heard suggest that you'll get 1/4 typical minimum, 1/3
usually, and about 1/2 AH/watt..

This was confirmed recently by someone who came to check out my wifi,
whose 250W through an MPPT controller reliably gives an average of
80AH/day in St. Petersburg FL, for the last 8 months' experience.

I expect my 360W bank to provide us minimum 90, and probably more like
180 given that we're in the tropics (well, will be when we get there),
and on the order of 120 during our Bahamas winter time. During the day
here in St. Pete, with my batteries typically full because it easily
keeps up with our profligate use of electricity, but no electronics to
speak of, I routinely get 15-20A mid-day, and from 7 on get 7 or more
until the sun's up, or it's going down. If I have a 12 hour sunlight
day (typical in the tropics) and the top is 20-25A in peak times, I see
it as reasonable to get the above.

However, I'd love to be proven wrong and get a full 300AH from our
bank!!

L8R

Skip and Lydia, on the boat, over wifi while Lydia talks to her mother
in England on Vonage, free with the unlimited package we buy...

You could use a home water heater 120/240V AC thermostat on 12V DC. I just
needs contact with the inner tank. If the water heater has a 120V
thermostat, disconnect all the 120V wires and use it for 12V.
Lee Haefele
"Sailaway" wrote in message
...
"Geoff Schultz" wrote

You can get elements that have both 120V AC and 12V DC feeds. See
http://www.svhotwire.com/divert_loads.html


GBM wrote:
That's great, but:
- how is the water temperature controlled? Temperature should not
exceed
49C to prevent scalding (used to be 60C)
- Once water reaches maximum temperature, what do you do then?

Seems to be of limited value if engine is also used to heat water. Our
hot water gets up to about 45C after an hour of motoring at low speed. It
is self limiting because of engine thermostat.

Just curious because I'm not familiar that with them - do marine water
heaters have any sort of provision whereby you can insert a temperature
sensor, which can then be hooked up to a limiting circuit?