You should design the whole thing using scrap items.
Here is my idea:
Solar panel - One VW panel should do. Use the embedded controller too. Heck, use your own controller! Connect that stepper motor windmill in parallel as well. Lamp - salvaged, repaired & painted. SLA Battery. Old UPS 7AH one. LED bulb - handmade, using my recipe. By using one PWM circuit (I build one using a 555 timer) you could dim the light when you don't need it so bright. Wires - new. Telephone wires? UTP cable? LED controller - LM 117 adjustable voltage regulator set to output 9V for strings of three LEDs. This way you will have power even when the battery goes down to 11.8V.
220 USD is WAY too much in my opinion. DIY skills can lower that cost. To me time is the most expensive asset.
Claude
Wunner'n
Doug[ Parent ]
With respect to G-s post. I'm with you, but I would scrap the SLA and go with a NiCd set. I have been testing these and can run a 12Vdc LED set on 10.80Vdc and they light up with almost as much brightness. Plus they can be run down to near empty >20% charge left and come right back up.
Cheers Bruce S [ Parent ]
Go for 3 volts instead and use small encapsulated panels in series and parallel for your requirements. Nicads are the way to go, charge them and let them run completely down, recharge them again. If you match your solar output to your daily usage you can just let them run down (like outdoor solar garden lights). Nicads can cycle everyday for 3 or 4 years or more without replacement.
You could get the system down to little money out of pocket, especially if you score cheap garden lights and use the batteries and leds out of them.[ Parent ]
It's simple to make. One thing is that it won't go down to 0% or up to 100%. You could adjust (by using germanium type diodes) the output in between 2% -- 99 %. It's good enough for me.
I made it and used it along with a LM117 voltage regulator and a MOSFET-based current limiter and so I got a regulated voltage¤t driver + PWM adjustment. Sweet.
It all looks like this (to the right, the 555-based PWM):
[ Parent ]
Claude[ Parent ]
Thanks Again Bruce S [ Parent ]
