This is my second (and only other) question for the experts here, my first problem was resolved perfectly thanks to the help I received. First a little background; 6 months ago I decided to leave the rat race and fit out a box truck as a self sufficient home complete with solar electricity and solar hot water.
I have just one remaining annoyance with the PV system; I have a 2000W modified sine wave inverter and a 600 watt true sine wave inverter both 12V/120V and both with over-voltage protection. This means that with an input of above 15.5V they will each trip and need to be manually reset.
The problem with this is that several times during the day due to various loads switching or the PV controller changing mode the voltage will momentarily climb to 16V before being attenuated, this happens in the blink of an eye too fast for a voltmeter to register it BUT the controller records it and the inverters trip. The controller manufacturer refers to this as “battery bounce” and states that is due to the type of battery I am using, however to change battery types is a $1,600 cost I can't afford. When I leave the “home” a 16V surge is likely to shut down the fridge until I return to reset the inverter; Not a good thing so I need a fix.
I estimate that the surge is well under one second duration and only rarely occurs, I need to limit this surge voltage to below 15.5V but without the limiter drawing load below normal charging voltage of up to 14.8V. How many amps this circuit/device should draw as a dummy load will need to be ascertained by trial and error but I expect 300w or 25 amps would do. As this load will only be active for a fraction of a second it will be of no consequence to my overall efficiency.
I was thinking a dummy load resistor in series with a large Zener diode both across the 12V PV output?
If not possible maybe a small zener powering a relay coil which then switches a dummy load?
Any thoughts appreciated.
I have just one remaining annoyance with the PV system; I have a 2000W modified sine wave inverter and a 600 watt true sine wave inverter both 12V/120V and both with over-voltage protection. This means that with an input of above 15.5V they will each trip and need to be manually reset.
The problem with this is that several times during the day due to various loads switching or the PV controller changing mode the voltage will momentarily climb to 16V before being attenuated, this happens in the blink of an eye too fast for a voltmeter to register it BUT the controller records it and the inverters trip. The controller manufacturer refers to this as “battery bounce” and states that is due to the type of battery I am using, however to change battery types is a $1,600 cost I can't afford. When I leave the “home” a 16V surge is likely to shut down the fridge until I return to reset the inverter; Not a good thing so I need a fix.
I estimate that the surge is well under one second duration and only rarely occurs, I need to limit this surge voltage to below 15.5V but without the limiter drawing load below normal charging voltage of up to 14.8V. How many amps this circuit/device should draw as a dummy load will need to be ascertained by trial and error but I expect 300w or 25 amps would do. As this load will only be active for a fraction of a second it will be of no consequence to my overall efficiency.
I was thinking a dummy load resistor in series with a large Zener diode both across the 12V PV output?
If not possible maybe a small zener powering a relay coil which then switches a dummy load?
Any thoughts appreciated.