A New Solar / Wind Charge Controller Based on the 555 Chip

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Here is a brief video I shot during the test run. It shows how the charge controller automatically switches over from charging to dumping when the upper set point is reached. Multiple solar panels and/or wind turbines can be connected to this unit. All the power sources can be connected in parallel and fed into the single input connection. Each individual solar panel or wind turbine needs to have its own blocking diode though. Here is a diagram of a typical system with a wind turbine and two solar panels feeding the charge controller. Typically an AC inverter is included in the system to power AC loads. Click on the image for a larger version. People write me and ask why they need a charge controller and batteries? Why not just connect the solar panel or wind turbine directly to the inverter and be done with it? Well, the answer is that the sun doesn't always shine and the wind doesn't always blow, but people want power anytime. The batteries store power when it is available, for use when it is needed. I may develop a printed circuit board for this project, if time permits and there is sufficient interest. I'll post further updates on this project as it progresses. UPDATE My friend Jason Markham has created a PC Board layout for this project almost as soon as I posted it. Click the PCB to go to his web site. UPDATE People are writing me and asking if this charge controller can be used with 24 Volt systems, 7 af 9 and what changes would be necessary. The circuit should work fine for 24 Volt systems. The relay will need to be replaced with one rated for 24V coil voltage, and the pots will have to be re-calibrated for new high and low set points for the higher battery voltage. The 7805 voltage regulator is rated for up to 35 Volts input voltage, so no other changes in the circuit should be necessary. UPDATE In an effort to create a compact, neat and portable solar power system, I have mounted the charge controller on top of a battery box. I have also mounted an AC inverter on the box. This is a much larger and higher capacity battery than I was using in my early tests of the charge controller. The inverter and charge controller are mounted on the battery box with industrial strength, sticky-back Velcro. Here is another view of the setup. As you can see, I have also included a cigarette lighter style plug for powering 12V DC loads. It is a complete solar power system in one small (but heavy) package. All I have to do is connect a solar panel or two to it. I can't wait to try it out on my next camping trip. I'll have plenty of power in the wilderness. I have finally decided to ditch my old battery bank, which I had been lugging around on my wilderness outings for years. It was a bank of 14 smaller 12V AGM batteries. I got the batteries essentially for free, so I wired them in parallel, put them in a plastic bin, and used them with my portable solar/wind power system. The setup was very heavy and unwieldy. I kept telling myself I'd get rid of it and go with one big battery once the little batteries started dying. They hung on for years and years. I must have been treating them right. Finally they started loosing capacity and dying off one by one. So I went out and bought one big battery to replace them all. It is about the same size and weight as a car battery, but it is a deep-cycle design, perfect for solar/wind systems. It has about the same AH capacity as the old bank of 14, but is much smaller and quite a bit lighter. It only set me back about $200. If it lasts as many years as the old bank, I'll be very happy. My back will also be happy that I don't have to lift the old bank of 14 batteries anymore. 8 af 9
UPDATE This 555 based solar charge controller project has won first place in the Utility Category of the 555 Design Contest!!!!! Yahooooo! For anyone interested, here is a Youtube video of Chris Gammell and Jeri Ellsworth announcing the 555 contest winners. The bit where they talk this project at about the 47 minute mark. Just to clear up one detail mentioned in the video, this project was not actually created to be a contest entry. I had already had my "Eureka Moment" about using the 555 to replace a whole bunch of parts in the original design, and was building the prototype before I even heard about the 555 Contest. It just turned out to be great accidental timing. Hearing about the contest did spur me to quickly finish the prototype and get this web page up in a timely manner though. Many thanks to Jeri, Chris, the other judges, and the sponsors of the contest. [Back to Mike's Homepage] [Email me] Other places to visit: [Mike's telescope workshop] [Mike's home-built jet engine page] [Mike's Home-Built <strong>Solar</strong> Panel page] [Mike's Home-Built <strong>Wind</strong> Turbine page] [Mike's gold prospecting page] © Copyright 2011 Michael Davis, All rights reserved. 9 af 9
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A New Solar / Wind Charge Controller Based on the 555 Chip

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