[Public-list] Solar Panel

[Robert Kirk]

At 04:08 AM 12/4/05 -0800, Peter Staehling wrote:
>Do you guys usually stay hooked up to shore power and
>have a trickle charger running when the boat is not in
>use?

Pete... Isobar swings at a mooring so I can't use shore power.  Up until an 
unfortunate windstorm last week, I had for about 10 years,  a small ~ 5 
watt portable solar panel which I would  rig topside for when Isobar was on 
the mooring during the week or on the hard over the winter as a trickle 
charger. It wasn't really necessary since all it did was offset a battery's 
self discharge which is minimal anyway. I don't use an electric bilge pump 
(I have a wave driven mechanical one.) so there is no load beside self 
discharge while she's moored.  My batteries didn't die even if I didn't use 
the solar panel for a couple of months, nor did I  need a solar panel the 
first 5 years I had the boat.

>After the comments from the group and looking at the
>logistics of buying and installing solar panels, I am
>thinking that for the short haul at least, I will not
>buy panels with substantial charging capability.  I
>still an thinking of a small panel to keep things
>topped up at times when the boat sits unattended for a
>while (especially over the winter).

That's probably a good idea. With a small cheap panel you can help top off, 
but  it would take a month to recharge a dead battery. For that you would 
need the expensive ugly array of panels that John Birch mentioned. They 
seem only useful for long distance cruisers who spend a lot of time at 
anchor and watch TV, etc.


>George's comment about "equalizing charge" has me
>wondering about whether I can charge both batteries
>with one panel.  I assume "equalizing charge" means
>that it independently charges both batteries at the
>same time.  Is that right?

George's type of charger is only applicable if you keep your boat at a pier 
with electricity available. An equalizing charge  is a short time 
overvoltage charge every once in  a while, meant to blast the crud from the 
battery plates. It doesn't have anything to do about independently charging 
the batteries - though George's neat new charger will do that, too.

>One other naive question.  There were comments about
>upgrading the alternator and the voltage regulator.
>How do I know what I currently have?  Can I tell by a
>visual inspection?

I'm not sure I would worry about  upgrading the alternator. I have whatever 
ancient alternator that came with my atomic-4 and it keeps the batteries 
charged. My electrical use is modest. For day sailing, the short motor use 
in sortie and returning to the  marina makes up for the autotiller which is 
about the only drain while sailing.  For overnight and longer cruises,  I 
only add drain from cabin lights, fan, & an inverter to recharge all my 
electronic toys. The power budget is easily balanced by the motoring 
necessary in a typical Chessie summer cruse and motoring the last day 
homeward bound with a case of get-homitis.

For ship's power I use 2 deep discharge 12V batteries and get better than 5 
years life each. There is no need for a high current "starting battery". 
The deep discharge batteries do a fine job of starting the faithful A4 
without even paralleling them. Beware "Starting Batteries" or "Dual 
Purpose" batteries; they can't take a significant discharge and will die 
young. (Maybe you need one for a diesel? I don't know.)

Bob Kirk
Isobar #181


 1133725103.0