Solar battery charging/LED setup

Post anything about batteries here. Lead acid, rechargeable, whatever.
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dyeager535
Posts: 2
Joined: Fri Nov 09, 2012 12:15 pm

Solar battery charging/LED setup

Post by dyeager535 » Fri Nov 09, 2012 3:37 pm

So first, thanks for inviting me over! You really seem to stay on top of your posts, and your videos are fun to watch.

I haven't done a TON of research on it, but from what I did find, if not careful, slow charging NiCd and NiMh batteries can be harmful to them. The belowsetup has been running for two years on the same batteries thus far, so the "slow" charging so far (at best I'm guessing 300mAh into 5000mAh batteries) doesn't seem to have hurt them. I am fairly confident however that the storage batteries will be cooked in the summer, after I increase the charge current. I have yet to find a very cheap/small charge controller that will stop the batteries from overcharging. If I could get my hands on a small one of those, I'd be confident the batteries would last just as long as they have so far.

I haven't gotten my 410mA 2V panels yet, but if I ever got really good sunlight (not likely in winter in the NW) once my "array" is built, I'll have 1A going into 5000mA rated storage cells. If nothing else, I'll have quadrupled the available current, even if it's half of that based on sun exposure, it will be better than it is now.

What I did was take a couple of these http://www.harborfreight.com/solar-spot ... 95388.html and disassembled them. These lights are/were unique in my opinion because they do not use a photocell to control circuit operation...once the setup detects voltage from the solar cell, it shuts off the light, and starts charging. Also, the little solar panels are just screwed to the light housing...you can remove those and screw them directly to a board. There is an on/off switch that is easily bypassed/removed. The three LED's are attached to a very small circuit board that would be easy to mount/use somewhere else. I don't know how it could be correct, but I measured the output to the LED's at tenths of a volt...I expected to see somewhere around 3V. I verified multiple times...

I mounted two of those panels to a board, and stuck it on my roof. Using scrap telephone wire (just a long term experiment at this point) I extended the leads from the panels to a water-resistant battery box I made (repurposed a bad cordless drill battery housing) which houses two Harbor Freight NiMh 2500mAh D cell batteries. From the box come the leads FROM the batteries, which powers the three LED circuit board from the donor light. The circuit board that controls operation is contained in the battery housing.

At full brightness these LED's provide a very effective night light through the prismatic glass in the bathroom. Unfortunately with the two original panels, and our dim light during winter, the batteries get hardly any charge. I have some AA's that are 2700mAh that I will probably use in place of the D's, which will shrink the size of the battery holder by quite a bit, while increasing capacity.

The eventual intent is to mount the panels somewhere a bit higher with more exposure (like one of my large trees) and bury the cable/control box. Original intent was a solar powered driveway light, but I may stick with the LED night light. Really handy this time of year, being up before light, and going to bed well after dark.

rfnreynders
Posts: 6
Joined: Sun May 19, 2013 8:19 am

Re: Solar battery charging/LED setup

Post by rfnreynders » Sun May 19, 2013 8:50 am

Check this out !
http://www.youtube.com/watch?v=lvKa4zneaRQ


grtz

Rene / EMC4U2

techman
Site Admin
Posts: 1329
Joined: Thu Dec 22, 2011 11:49 am

Re: Solar battery charging/LED setup

Post by techman » Sun May 19, 2013 9:53 am

Wonder if someone has time to try this out at home. I am in the middle of so much construction here right now it will be a while before I get my electronics lab back in shape.

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