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Old 12-12-10, 05:08 PM   #5
Xringer
Lex Parsimoniae
 
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Default Solar+LED=Bliss?

Well, I got another LED array (for a total of four) and did a little current test last night.

I wired all 4 in parallel and connected them to 12.54 volts. They used about 2.7 watts total!
Since they were rated for 30volts, I decided to try two batteries is series.
At 25 volts, they got brighter, but the watt meter displayed over 20 watts!!


Very warm!! I quickly went back to using 12.54.. I left the array running until midnight,
and checked the battery voltage every hour of so.
The old Toyota battery must have warmed up a little, after sitting on that cold 60f floor,
because in about an hour, the voltage went UP to 12.59v!
It stayed at 12.59v until midnight.

At midnight, I switched to the smaller Honda CRV battery, and let it run until the next morning.

Toyota: 10.8 Wh and Voltage went up for some reason.
Honda: 18.1 Wh voltage dropped over night. 12.54v to 12.28v

Anyways, I've decided to make these into a small reading lamp for the headboard.
They are good enough for reading and as backlight for watching the little
20" LCDHDTV that's mounted on the wall beside the bed.


Anyways, if my wife and I use this light for a few hours a night, that 2.7w
discharge rate can easily be made up by the 10w PV that's charging the battery.
Under average conditions (unless the sun is absent for weeks on end),
I think for each hour of good sunshine, we should get over 2 hours of good LED lighting.
It's very likely that the SOC will remain high, on average.
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