Solar panel for boat battery
JERD
between fising trips and extended non usage.
What size panel would you suggest - that will not require a regulator?
Would 1 amp be OK or is that too large?
JERD
Eric Sears
You haven't really supplied enough information.
What is the capacity of your battery?
Approximately what are the "sun hours" where the boat will be left?
(I am presuming the battery is to be left in the boat - as otherwise a
small plug-mounted smart charger would be better).
But if you are talking about a battery of 80 -100 amp-hr size, about 1
amp-hr per day is probably enough. For this a panel up to about half
amp rating should be sufficient - and will only lead to a small amount
of lost water by electrolysis without a controller of some sort.
Topping up each month or two should be sufficient.
At one time solar panels were available having only 32 cells, which
were called "self-regulating" because they had very much reduced input
when the batt voltage rose to 14v. I haven't seen them on the market
recently - but you could approximate the same by putting about 4
silicon diodes in series with a standard type of panel (either
crystalline or amorphous). Probably the "open circuit" volts (in full
sunshine) should be about 15 - 17volts when measured through the
diodes.
This is an idea I haven't tried, but I think it would work.
Although you say "not require a regulator" - perhaps you should look
at the low cost regulators which are available. Compared with the cost
of a solar panel - a small 2 amp regulator might be a good investment.
Eric Sears
