Hi,
I've rescued several small PV panels along with a pair of gel-cels from an electric wheelchair that still have useful life. I'd like to put together a charge controller to run the irrigation pump "for free".
Any pointers to suitable designs? The PVs are small so Isc is on the order of 100-200mA (though I may double that)
On 11/4/2009 2:09 PM D Yuniskis spake thus:
I found this one at Harbor Freight:
I thought I had seen smaller ones there, but didn't find them. Perhaps a more careful search might turn them up. They do sell some very small solar battery charging kits, including panels, for cheap, so they probably have smaller controllers.
-- Who needs a junta or a dictatorship when you have a Congress blowing Wall Street, using the media as a condom? - harvested from Usenet
On Wed, 04 Nov 2009 15:09:47 -0700, D Yuniskis put finger to keyboard and composed:
If the battery capacity is big enough, and the PV panel voltage is not too much higher than battery voltage, then you won't need a regulator, only a 1N5817 Schottky diode to prevent the battery from discharging into the panel.
- Franc Zabkar
-- Please remove one \'i\' from my address when replying by email.
This is inefficient. You want to find the "sweet spot" where you get the most power from the panel. I.e., at no load you get no power and at short circuit the same applies.
Ideally, you want to coax the most from the panel by operating it where it "wants" to be operated. Then, move this into the battery incurring the least losses possible in the process...
What is the power requirement of the "irrigation pump"? The pumps I've used wouldn't run long off of a couple wheelchair batteries.
I'm harvesting rainwater. So, I only need to move a few hundred gallons at a time (i.e., I'm not watering an orchard! :> ). I'm more concerned with restoring the level of charge in the batteries quickly enough with these tiny little PV's...
On 11/5/2009 8:48 AM D Yuniskis spake thus:
Did you check out that Harbor Freight link I gave earlier? Hell, for as cheap as they are, you could get one of their smaller solar battery charger kits, with controller, and just add your panels to theirs for more power.
-- Who needs a junta or a dictatorship when you have a Congress blowing Wall Street, using the media as a condom? - harvested from Usenet
aka Maximum Power Point Tracker. Google MPPT
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.