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Improving a small solar charge controller for higher amps, ideas.. (Read 6198 times)
electron
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Improving a small solar charge controller for higher amps, ideas..
Jun 7th, 2011 at 5:43pm
 
After seeing posts and videos about this controller, I had some ideas to improve it.

XRinger posted pics of the insides, it looks pretty simple, and looks like all they do is simply switch a mosfet on and off like a relay.

The mosfet looks to be a IRFZ34, which is rated 30A at 60V, 88W dissipation, on resistance is .05 ohms.

So I am thinking you could run this at higher amperage than the rated 8A somehow. You could push that mosfet to 20A no problems.

Mosfets are easily paralleled, and there are two more spots on that heat sink already pre-drilled. You could wire in two more and just connect them all in parallel. In most circuits I've seen they just put a 50 or 100 ohm resistor in series with each gate.

From the pic I can't tell what the diodes are but all you would have to do is parallel more diodes on top of what is there to increase the current they can handle. They look to be at least 5A each.

You could increase the size of the heatsink easily (if needed, you would have to test that since the mosfet has a pretty low on resistance) by just bolting on more metal and not use the plastic case it came in.

The wire size and possibly the main circuit traces may have to be beefed up, easy to do by just soldering some extra wire on to the bottom traces. I've seen them do that in some inverters.

Fearlessthinker posted some testing results and found that it would draw 1 mA from the battery at "night" and doesn't trickle charge, it actually draws 5 mA from the battery when it shows that the battery is charged, meaning the mosfet should be off.
http://www.youtube.com/watch?v=FORTX-4p600

I'm not sure what to do about the 1 and 5 mA draw. As soon as someone draws a schematic I am sure it will be easy to spot why that happens. There may be a way to put a cmos 555 timer chip in there and eliminate a lot of that circuitry and possibly the 5mA draw.

All in all, for about $20 you get a nice circuit board and case, and for another dollar or two you might be able to make it work at much higher amps.

It looks so simple you could make your own with parts you have laying around!

(just so it's clear, I don't own one of these, just going by what has been posted so far)

XRinger's original post:
http://www.wind-sun.com/ForumVB/showthread.php?t=10326
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« Last Edit: Jun 7th, 2011 at 5:55pm by electron »  
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