Modifying 12v controller

[RobT]

A friend has just blown his Xantrex C60 Charge controller, fried 4 100 amp transistors, which can be replaced, but also damaged the PCB, for which I need a schematic. A week searching, no go!  I have found another schematic for a 20 amp controller, but it's only 12v. Any ideas as to whether I can modify it to take 24v in?  The idea is to make up a couple of these to replace his Xantrex, IF it's possible. (He's running 12 x 120w solar panels, and puts out around 55 amps!)

Any help at all would be much appreciated!  Thanks! RobT

Hopefully the schematic will show up below

[Flux]

Rob

At a quick glance it looks as though you need to change Z1 (24v)

R1, about double it and possibly you may need to tweek R2 a bit.

You ought to check the voltage spec of the Mosfets, but probably they are ok.

Flux

[baggo]

You might have to watch the voltage into the 7805 regulator (IC3) as well. I think the maximum input voltage is 30 to 35 volts and you may exceed this if the panels are lightly loaded. Probably just increasing R12 will be OK. I see that this circuit uses a dump load whereas a lot of charge controllers just short out the panels which seems a bit of a waste. You could make the dump load a water heating element and utilise the wasted power.

John

[Nando]

Rob:

The Xantrex C60 controller is a low frequency ( about 100 Hz as I understand it) using a small microprocessor to limit the current to 60 amps and as well to detect the voltages of interest.

It seems that the schematic, you are showing, ( too dim and missing connections )is from one circuit offered by Home Power if it is such, reply to me directly and include the schematic, the tell me the solar panel total voltage a peak sun as well as the current capacity of the solar panels.

With this info I may be able to tell you what type of circuit changes you need to do to work with your friend's system.

A better design would be a PWM charger controller like the ones made by OUTBACK Company that operate about 30 KHZ and do a much better job.

Regards

Nando

nado37 at comcast dot net

[ibedonc]

that circuit is from here - http://www.solorb.com/elect/solarcirc/scc3/index.html

and the mosfet is rated for 55v 74 amps