On December 23, I was quite happy that the new prototype pump controller circuit didn’t blow out in the 30 seconds or so that it took to burn out before I worked out a solution to the voltage spike issue.

From that point, I left the pump running 24 hours a day until today, and the good news is that the controller circuit is still going strong.

The bad news is that the temporary vee belt we installed broke some time overnight:

This isn’t a big surprise. We initially bought an adjustable one that you cut down to size and then screw the end together with a small metal latch. This gave us a chance to test the pump and find out what is the right size that won’t slip off. The first few times it did slip off within a few minutes so we adjusted the tightness, and in one case had to trim down the length. Well, now it ran for over 100 hours without pause and didn’t slip off until the latch came undone, so I figure this size works. Now we should try to find a more permanent vee belt manufactured to this size and hopefully that one will last a lot longer.

Over the course of the test, since the pump was running 24 hours a day, the batteries discharged at night but were charged by the solar panels during the day. This was the peak charge power I saw on a very sunny day around 11AM:

15A @25.2V comes out to about 380W of battery charge current, which might correspond to about 450W of solar power of the controller is 80%-90% efficient. This is still less than the 600W the panels are rated at, but most of the way there. I still believe that the charge controller may not have any voltage boost capabilities, and the panels may not be able to push 24A at 25.2V (maybe closer to 26V on the input side since there is presumably a transistor of some form controlling the charge rate) in order to produce full power. I think I will experiment with a better charge controller once the shops open after the New Year holiday to see if I can get the rest of the power out of these panels.

Still, having enough juice to run a pump for 24 hours per day, 7 days per week without any charge from the mains electric supply is pretty cool.