Sep 1, 2008 09:48 am
Re: using 12v dc appliances during the day
Got to answer my own question yesterday. Now that I have my system up and running. The laptop pulls 1.6 amps. I have 60watts of solar making 3.4amps+/- of power during the day.
I turned on the computer hooked up via DC only.(no inverter) at 10:30am and was able to run a very intensive application that kept the computer draw at max 1.5 amps continuously.
The day was full sun and I was able to run the computer non-stop till 4:30pm in the afternoon without pulling amps from the battery. The charge controller kept flipping back and forth from "charging" to "charged" state for the battery about every minute or so, keeping the battery fully charged all day. After 4:30pm I disconnected the computer and allowed the system to run normally with the battery showing "charged" on the "Trimetric" meter.
So....running 12v DC appliances during the day greatly extends run-time, as long as the load amps are less than the array amps, you never really touch the battery bank.
This reminds me of an article from Home Power Magazine, where the off-grid couple had a massive array for their daytime use and only needed a 650ah bank that they cycled only about 30% deep.
This is sort of the reverse way of designing a system, in that you see sun as "the battery" and concentrate on maximum direct "solar power" for daytime use and size the bank for just simple night-time use-age. Since I'll be using the studio only during daylight hours, this scenario works perfectly.