Xantrex C40 PWM 24v in to 12v out did it work?

Yep. Heated the controller up a bit and wasn't effient at all but it worked. Ran it for a week that way. Why? Why not it was working. Totally pointless but proves the C40 is near bullet proof as long as it isn't shot at.

Sounds interesting but,

More details please?

More details? Okay. A PWM controller is 12v in 12v out, 24v in then 24v out, they can't be mixed like I did. PWN was the original solar controller design, it simply took the 20ish VOC from the panels and well, bridged it to the 13-14v a 12v battery needed to charge while regulating the amps to prevent overcharge. The PWM was amazing at the time but NOT in anyway a MPPT. Panels on a PWM are always parallel unless using a higher system voltage then panel voltage, however you typically can never put 24v into a PWN with 12v out- the PWM can't do anything with the extra voltage like a MPPT can so it's bad, forbidden and could fry a controller.

The C40 now owned by Scheider Electric was designed at the time with protection after protection- thermal, reverse polarity, other stuff I don't care about. I simply looked at it's then advanced design as a 12/24/48v controller with a jumper one sets for a 12, 24 or 48v system, set it to 12v, turned the rotary knob for 14.6v bulk/absorb and the other dial for 13.6v float and shoved 24v into it and it worked. Totally pointless but it allowed it to work and didn't balk, error out or amazingly overheat after a week. That's it.

Only thing I hate about the C40 is the hardcoded 2 hour absorb time.

Kcp said:

More details? Okay. A PWM controller is 12v in 12v out, 24v in then 24v out, they can't be mixed like I did. PWN was the original solar controller design, it simply took the 20ish VOC from the panels and well, bridged it to the 13-14v a 12v battery needed to charge while regulating the amps to prevent overcharge. The PWM was amazing at the time but NOT in anyway a MPPT.

Click to expand...

There's no harm in using a '24 V" panel & 12 V battery bank with a PWM controller. You will be getting only about 50% of the panel's rated capacity. The controller will do just fine. Depending on the control loop algo for absorb, you may see some wild swing in volts/current during absorb.