Tuesday, August 16, 2011

Solar Buoy

My family has a place in Georgian Bay, Lake Huron.

It's remote, and fairly primitive. The entire area is solid rock, occasionally covered by scrub brush and pine forests. The area itself is a deep lake broken by numerous islands. Occasionally a spire of rock is completely surrounded by deep water.

Marking these rocks is a completely DIY effort. Some islands in the area have fairly decent markers.

Our island is not one of them. The vast majority of our markers are empty 1 liter to 1 gallon bottles, with rope. I don't know if they're weighted or actually secured to the obstructions they mark. They seem to stay in place, despite the hard freeze that occurs every year.

Some of these markers are small enough that they're virtually invisible during daylight glare. Forget about trying to see them at night. It's just not going to happen.

For many of the visitors, this isn't a problem. They know the waters like the back of their hand. These folks tear through the area at top speed, and some could possibly do it blindfolded and survive.

I, on the other hand, am not that daring yet. I think I'm a pretty good boater, but I definitely lean on the side of caution. There are times when I'll put someone in the bow of the boat to warn of unmarked obstructions.

I've been going to the island routinely for four years now. One of the things that strikes me is the pure beauty and nature of the area. Anything man-made is the exception to the rule, and it is very easy to keep a "Green-Mind" while I'm up there. I decided my first year to make my Islander Projects as green as possible.

While in Canada, we saw some cheap solar garden lights (Less than $3 at WalMart). We picked one up to mark the path to our camp from the opposite side of the island (we do a fair amount of late night partying). Looking at the light started the ball rolling for a solution to marking shoal hazards around the island.

I wanted a cheap, solar powered solution, with the ability to program the (potentially multi-colored) light pattern. In terms of buoy, I wanted a 4-6" PVC pipe, with a solar collector on top, a battery, and a BlinkM LED in a sealed enclosure.

I hit Home Depot yesterday, and grabbed one of these guys:

Mine was just under $10... Your mileage may vary.

I disassembled and opened everything up as much as I could. The whole thing is basically a solar array, a 3.2V Lithium Battery, and a circuit board. I wasn't able to figure out how to completely disassemble the unit to get at the pieces-parts I wanted, so I grabbed my Dremel.

I cut the sucker:
If you cut along this line, you will miss the circuit board while still preserving the reflector and lens assembly. Take caution to avoid the wires. I then did an additional cut to create a channel to free the wire from the upper connection hole. This allowed me to get the circuit board removed, and I was left with a small, intact system comprised of a solar cell, circuit board and LED's, and the battery.

I fired up the soldering iron and removed the LED's. Thankfully the LED's all use the same ground and power lines. I didn't want to spend too much time figuring the circuit out (later, ok?). I marked which side of the LED's were notched (in the top view of the board, the sharpie scribble in the bottom of the picture is supposed to be an "N").

I then cut one of my breadboard wires in half, so I would have two easy female sockets to supply to my BlinkM.

The images are from the ThingM website and SparkFun.

There are a bunch of cool things about the BlinkM LED module. First, the cost is pretty low at ~$13. The next is the form factor. These things are pretty small. Third is the well integrated multi-color LED, with the stand-alone microprocessor to control it. You can program the LED patterns, and then just supply power. The system will blink, fade and change color, however you have programmed it.

All of this makes it perfect for this project. The cheapie solar array, battery and board will store power, and then supply power to the LED's when the light level goes down. From there, the BlinkM just does it's thing. ThingM has even provided a very easy graphical programming tool for the BlinkM's

I used the breadboard wire to connect the power to the solar array, so that I could easily remove the BlinkM to program it. Once it is programmed, I just hook the power up to the board. The "notched" side of the LED's is the negative feed. You can see in the circuit board picture (Picture #3) above how I soldered the wire (again, you do have some options here).

I tried the system out, last night, and it lasted all night. I didn't really do a formal test of the charging time versus discharge time, but the LED was blinking away this morning after being in the dark for 12 hours.

I need to figure out how to mount this thing. Clear four inch PVC pipe is hideously expensive. I think I'm going to look for a clear Pelican case or Otter Box. That still remains to be seen. I also want to work a switch into the BlinkM connections so that I can re-program these things if I need to.
Finally, I'm going to get a $3 solar light from Home Depot, and compare that one. If I can get the same (or similar) performance for less cost, I'm all for it.

There is one possible upgrade, and that is to a BlinkM MaxM. These things put out an insane amount of light, but I think I'd need to upgrade the power. As it stands, this thing is completely kit-bashed, with no real original circuitry on my part. I think I would have to actually do some circuitry work to get a BlinkM MaxM running off of a solar charged battery.


Malibu Solar Powered Flood Light $10 Home Depot
BlinkM Module $13 SparkFun Electronics

Enclosure: TBA