Thanks for the replies. Unless I am missing something the formula is sound
but not worded correctly? I will try to find more info on this. The reason
behind the extended formula's is for better understanding and also the end
result and second part of this question is that I plan on hooking this up to
a solar panel if possible. I was trying to get an idea about what I would
be using per day/hour if run 24/7 and what size panel I would need for this.
Then depending on how that works out $$$ wise for the size panel I would
either stay at that or look at some kind of timer setup that would allow the
unit to run for X hours a day. I would rather have it on 24X7 but the
actual real world usage of the unit would be around 3 hours per day on a
weekday and posssibly more on the weekends.

So I am still needing some help with the panel size I will be needing to
keep this thing up and running.

So given 144 watt-hours per day would that work out to?

144 / 5 hours of sunlight = 28.8 W panel?


"Bennett Price" wrote in message
. ..
I'm not sure you realize it but some of your figures/formulae are
unnecessary.

More simply Battery 110 AH (/2) Load = .5 A 55/.5 = 110 hrs

Typically batteries are charged at .10 of their 1 hr rate (when fully
discharged) but the type of battery (Gel-Cell, NiCad, NiMH, etc.), must be
considered. Also, while .1C might be good for a discharged battery, the
charge should diminish as the battery becomes fully charged (or some other
mechanism, temperature rise, e.g.), must shut down the charger.)

See the battery mfr. for recommended charge rate and charger technology.
Also, consider how fast a recharge you want. A 4 ampere charger will
recharge the battery (but slowly) as will a 100 Amp charger

Bryan Martin wrote:
The unit I will be using is 12V 0.5A

12V X 0.5A = 6 Watts
6W x 24hours = 144 Watts per day
144W / 12V = 12 amp hours

Now given a battery with 110 amp hours
(http://www.defender.com/product.jsp?path=-1|328|51495|306219&id=51496)

We should only draw the battery down 50% so we will actually only get

110 / 2 = 55 amp hours

12 amp hours needed / 55 amp hours available = 4.58 days
so with this battery we have enough juice to potentially run our unit for
4.58 days w/out charging.

Now if the above is not correct then please explain. And the next
question is how would I now figure out approx how large of a panel I
would need to keep the battery charged. I am really looking for the
formula and a understanding of how you got from A to B as oppose to "this
panel should work".