I've read through many posts here and learned a ton about Powerjack inverters already. My search for good solutions to the overvoltage shutdown problem that seems common to PJ inverters is what led me to this site, and the best answers I've seen so far anywhere. Thanks, thanks, thanks! Someone commented previously that Oztules was a genius. If not I'd have to say that he's at least a reasonable facsimile!
The last and apparently generally accepted fix is the 1 meg resistor soldered in parallel to the 10 meg resistor R14 (says cut if low next to it) on the control board, with the alternate being a 5.6v zener diode instead of the 1 meg resistor.
I do have some questions, though:
1. Does anyone know what the 1 meg resistor does to the setpoint? At what voltage will it shutdown now?
Does it not shutdown on high voltage ever now?
2. Has anyone tried a potentiometer at R14 to try to set the setpoint to where it should have been set?
3. Is a 1 meg resistor used on all voltage models? 12v 24v 48v? Other values?
4. If the value isn't important in reducing the resistance, why not just short the resistor? (Maybe the ic it feeds doesn't like zero resistance?)
5. I'm assuming the use of the zener instead is intended to prevent ANY overvoltage shutdowns, yes?
6. Does this change have any effect on the low voltage shutdown setpoints?
7. Could have sworn I had a couple more....
I'm not a fan of disabling safety functions, but correcting design errors is always good. A 12v "name brand" inverter generally has its high voltage shutdown at at least 16v, and as high as 19v. I would guess that PJ setting it at 15v on 12v units (30v on 24v and 60v for 48v units) is either poor understanding of the world market's intended usage, or more likely their attempt to safeguard substandard parts/poor quality assembly and limit burned units that get returned to them. Maybe both
If it sounds like I'm disparaging Powerjack, sorry. Not my intent. I actually agree completely with Oztules that for the money they are GREAT inverters, especially since he and others here have solved most of the design shortcomings.
So, with that all said, I would like to nail down a resistor value that sets the alarm/shutdown to say 17v (thats 68v on my 48v unit)
I can now prevent the annoying midday low load full sun high voltage shutdowns using that zener or resistor, but it would be nice to know that if something really DID go south, that there is still some protection in there.
So that's the current quest.
More to follow