Monthly Archives: April 2014

Battery Charger Controller

The next step in the construction of the Magic Bus, is getting some electricity going. Too many things are dictated by the need of electron flow. So it’s time to start. I figure the best thing to do, is to break up the blogs. This will be a little more technical than the other construction.

I am going to need a battery, a way to charge it, and something to control the charging of the battery. You can find systems that do this pretty cheaply on ebay, but you can get it a little more cheap if you do it yourself. I bought some solar cells on ebay. I got ten 4 watt solar cells for $17.84, and that is with shipping. That’s 40 watts for under twenty bucks. I will need more, but it’s a start, and for the price, I am happy. I haven’t got the battery yet, but I have built the battery charger controlling circuit. This is how I did it.

Don’t click on this link yet, but I first found this webpage where a guy tells how he built a controller. I started getting everything together to build his plan, and then I kept reading. If you read all the way down, you will find out that he ditched all that created a better one here. That link is really the only link you need to look at. If you want to know the history of how he came to make the controllers, then you can go ahead and click the first link. The second link is what I am going to show how I did it. First I would like to thank Mike Davis for his wonderful work. Who ever he is. Seems like a smashing man.

Here is a list of the items you will need, and a link to what I used from Radio Shack…

5 Volt Voltage Regulator
555 Timer
Push Buttons
10k Multi-turn Potentiometer, you need two.

Those are the main components, but you will need some resistors and capacitors.

Here are the resistors, you will need package of 1k ohm, 330 ohm, and 100 ohm. You will need this capacitor, the other capacitor called for a 0.33uf Capacitor, but my local store didn’t have one. So I used this capacitor and it works great with no problems. You will also need some LEDs, a green and a yellow. It also calls for an automotive relay, but I used a heavy duty relay that I already had. I had to change the schematics a little since my relay is rated for 6 volts. Here is what I did. The red is what I got rid of, and the green is what I added.


I followed those schematics, and followed the instructions from Mike, and I made a battery charger controller in a couple of hours. It works great. After calibrating it, putting under 12 volts on the battery terminals causes the green LED to light up but the relay doesn’t trigger. Put over 12 volts on the terminals, and the the yellow LED will light and the relay triggers. When I get the battery hooked up to it with the solar cells, the relay will stay off when the battery needs to charge, but as soon as it is charged, it triggers the relay and kills the power charging the battery. Here is mine. Maybe not the prettiest of all my circuits, but it works and it’s pretty simple. I even built my own heatsink from some aluminum. The voltage regulator needs it.

charger controller