Oshkosh Camping - Battery Power

[Tom McQuinn]

This year will be my 5th consecutive AirVenture. If ever there was a
born camping hater, it's me. But I have slowly gotten the hang of it.
Last year was fantastic, and I have some of the regulars here for the
ideas that made it that way. (Eye shades & ear plugs... how could that
have not occurred to me?)

Having electrical power for Game Boys and my throwaway laptop made a big
difference. Last year I bought one of these to charge a good sized gel
cell:

http://www.goldenpsx.com/image1.jpg

It worked fine but I'm not sure what would have happened in an 'over
charge' situation. Since several of you are expert in electronics and
engineering, can anyone take a quick look at this and tell me if this
unit would be advisable to use between the 12V solar panel (13 watt) and
a 12V gel cell? Not knowing what keywords to search on make this sort
of thing a bit difficult.

http://store.solar-electric.com/sg-4.html

Tom

[RST Engineering]

It is a little bit of overkill, but the price is sure right and it looks
like it will prevent serious overcharge.

Jim
--
"Dream as if you'll live forever. Live as if you'll die today."
--James Dean



"Tom McQuinn" > wrote in message
...

Since several of you are expert in electronics and
> engineering, can anyone take a quick look at this and tell me if this unit
> would be advisable to use between the 12V solar panel (13 watt) and a 12V
> gel cell? Not knowing what keywords to search on make this sort of thing
> a bit difficult.
>
> http://store.solar-electric.com/sg-4.html
>
> Tom

[Vaughn Simon]

"Tom McQuinn" > wrote in message
...

I have a bit of experience with PV systems and normally I never discourage a
charge controller but here goes...

For occasional camping duty, I don't know if you really need a charge controller
with that setup. You will only get full output from that panel when it is
directly pointed at the sun, and then the national average is something like
five hours per day (effective full sun hours). That optimistically comes to
something like 70 watt-hours per day from that panel. In four or five days of
camping and with normal loads, you are unlikely to seriously overcharge your
battery. If fact, it is more likely that you would damage your battery by
continuously draining it flat.

If you still insist on a controller, the one you found would do the job just
fine.

Vaughn

[[email protected]]

Tom McQuinn > wrote:
> Since several of you are expert in electronics and engineering, can
> anyone take a quick look at this and tell me if this unit would be
> advisable to use between the 12V solar panel (13 watt) and a 12V gel
> cell? [...] http://store.solar-electric.com/sg-4.html

I don't think I'd call myself an expert, but I have hooked up PV solar
panels before and IMHO this looks like it would do the job. It's even
somewhat sanely priced, something of a rarity in the solar power world.

On the other hand, I also agree with Vaughn Simon. The solar panel you
have is effectively a 1 A charger. If your gel-cell is bigger than
about 10 Ah, and you use some power from it every night, you'd be
hard-pressed to overcharge it with that solar panel alone.

If you have a digital voltmeter, you can check it out at home. Set up
the solar panel and battery, then measure the voltage at the battery
terminals on a sunny afternoon. If it never goes over about 14.80 V,
you're most likely not going to overcharge the battery.

Matt Roberds