Just got it soldered up yesterday, going to mount the heatsink and do some load testing today after work!

(The board works already, I've tested all of the voltages and they're all fine, but I need to make a decision for what kind of heat sink I'm going to use, so I need to do some load testing.)

There was a mistake on the board, specifically in the low battery part of the circuit. (Smack dab in the middle of the board.) I used the wrong package for the little NPN transistor and switched two of the pins. Nothing a few cut traces and bodge wires couldn't fix! I also made the board WAY too compact. Many of the pieces are VERY close to the regulators, meaning they're going to get hot. I underestimated how big some of the components were. If I were to make another one, I'd spread everything out a bit.

EDIT: Pics

It's going in this box. You can see the board and the battery (obviously.) Nothing is bolted down yet, I need to drill a bigger hole (it's 10:30 here!) Securing the battery should be easy enough, I'm just going to make some "U" out of aluminum. Maybe wrap the side that touches the battery in tape to make it more gentle. I'll put one of those on the right side above the circuit board and one on the top. (Of course the pictures posted upside down, take that into consideration.) Maybe shove insulation to fill in the rest. I'm going to put a piece of foam between the lid and battery to keep the battery from moving in and out (in the reference pane of the picture.) I'll probably do all of that tomorrow. Also, none of the wires are there, obviously.



Waterproof lid closed.

Circuit board. Three regulators attached to a largish homemade heatsink. You can see the two potentiometers (green things) that adjust the voltage on the far left and far right regulators. The one should be around 9V to balance between heat dissipation in the light and regulator, and the other one should be set to whatever my rear lights take! Don't mind the obvious bodge wire around the LED. The low battery light comes on around 10.8V. I think that's a bit high for most lead acid batteries, but I'm not one for completely discharging my batteries if I can help it! And the light should be plenty visible through the clear top of the box. The white connectors on the sides are as follows. (Battery, switch, 9V adj. out, 9V out and 4.2V out (for rear lights with 3 AAA batteries.)

I'm also going to hot glue everything in place eventually, especially the potentiometers, so they don't change voltage when I hit a bump!

Back of circuit board. I overexposed the copper, so it's patchy in places, but everything is connected just fine.

As for the load testing, I plugged my actual bike light into it today and it worked a treat! The regulator only got to 55C, which is absolutely fine. The light itself was warmer! Probably due to the increased voltage. But that's not a problem because it'll have a ton of air running over it when it's in use! Talk about the ultimate heat sink.

Speaking of which, my homemade heatsink worked fine. It it didn't work well enough I was going to flip it around so that the part at the bottom would be sticking the other way, then I'd cut a slit in the side of the box, so that part of the heatsink would be outside (in the cold!). I could also braze some right angle pieces on the aluminum and cut more holes in the side of the box, but for now it doesn't seem to get that hot, so I think I'll be good. I'll test it again eventually with the box shut, but the highest temp those regulators can run at is 125C, so I'm not even near it.

As for mounting it to my bike, I'm going to attach it to the side of my rack with some bolts. I want to make it quick release somehow, so I can bring it inside and not worry about the battery freezing when not in use. Alternatively I could just take the battery out of the case! That may be a bit easier since the battery is only connected by a few wire connectors.

Anyway, I should have it done in the next few days, definitely by next week! I'm also buying a new rear light for my winter bike soon, since my summer rear light doesn't transfer to the rack I have on my winter bike. (I stole the light my GF had on her summer bike for now... SHHHH, don't tell her.)