If you bought a higher quality set of solar Christmas lights, you can probably skip this step unless you really want to increase the capacity of the lights. I've not tested this yet, but I suspect the solar panel I used will be able to send enough power to the battery to light the bottles up for a while even on a gray and short day.
Testing the solar panel revealed that it was producing about 1.4 volts at around 100ma, which SHOULD be BARELY enough to charge the supplied 1.2v 1000ma battery. What I discovered was that the battery was a dud right out of the box, and even putting a functional battery in its place resulted in about an hour's worth of full power and two to three hours of steadily declining brightness.
Obviously this would not do.
My solution was to gut the whole thing, get a new and better solar panel and replace the single 1.2v 1000ma battery with a pair of parallel wired batteries that would work as a single 1.2v 5000ma battery. This is clearly overkill, but hey, it will definitely keep it's brightness for quite a while like this!
First you'll need to dismantle the solar panel and driver
. Really, the only part we're keeping here is the circuit board.
Next up, find or build a better solar panel
that can charge your new and improved battery pack. There are already instructables detailing both how to build a solar panel out of broken solar panels
as well as how much power you'll need to charge a battery with the sun
, so I won't duplicate them here. The general rule of thumb when determining how much juice you'll need is that you match of slightly exceed the voltage of the battery and get about 10-15% of the maximum amperage of the battery. I know that's not a super technical or precise explanation, but living by those guidelines I've never set a battery on fire or anything. The solar panel I made puts out about 2v at 600ma in full sunlight, more than enough to charge the batteries I used.
Speaking of batteries, I used two standard NiMH AA batteries for this project, wired in parallel
. That means positive to positive and negative to negative, rather than in series (positive to negative) like you see in most electronics. The difference is that when you wire in series you add the batteries' voltages, but when you wire in parallel you add their amperage. Since I knew the circuit board was designed to operate at 1.2v, I figured I'd keep that and just increase the amount of power available to it by 5 times!
After you've got your parts, you'll need to build some sort of water resistant case with a clear panel
to shove everything into. I used the paper catch tray from an old Epson CX5400 and a sheet of perspex from Home Depot, but you could use pretty much anything of the right size and shape!
Basically, I just installed everything as best I could and started hitting it with the epoxy and silicone. What I ended up with was a panel about 1 foot by 8 inches that had the solar panel in the middle, the circuit board on one side (with the control switch sticking through the back), and the batteries on the other. Check the pictures below and image notes for more details if you need them, but this is really just a step where you'll need to improvise.
After that was done, I built a little stand for it to be mounted to the top of the arbor, hopefully avoiding the grape leaves. I used cedar as I've heard about a million times that cedar is weather resistant.
After this is done, I recommend taking everything outside for a day and making darn sure it works before installing!