Contention Between Victron 100/30 and Morningstar PWM?

[jpendoley]

I just added a 200watts of solar to my bimini connected to a Victrom 100/20 MPPT controller. There is prexisting 160 watt array on my davits that is connected to a Morningstar Prostar 15M. When I flip on the Victron's breaker the current the Prostar is producing begins to drop. They are both wired to the same battery bank and the same posts (four 6Volt batts connected in parallel and series to yield 12volts and 400 amp capacity). Wjhats going on here? By adding the 200 watt panels I somehow am throttling the 160 watts on the davits...

[wholybee]

The interaction is complex, but the first question, what is the state of charge of the batteries at the time this happens? What is the total amount of charge current you are seeing? The most likely thing that is happening is that the battery is limiting the rate of charge, and so the current the battery will accept is being divided between the 2 controllers.

There can also be interaction based on the charge parameters of each controller. If you post all of the parameters of how the 2 controllers are programmed, maybe someone can find an issue.

[noelex 77]

It is likely that the solar controllers were just regulating the current to appropriately charge the battery. Try turning on a high load. The solar output should adjust to deliver the maximum output possible under the conditions.

[jpendoley]

Thanks Warren, the bank was high probably 12.8. You may be right because if I switch off the MPPT controller the PWM controller climbs to 8-9 amps but drops down to 2.5 A as soon as the mppt controller begins pushing in about 6A of current.
I think I will put a load on the bank to see how they work together with a battery that's not so full.

[mlydon]

Your problem is that the controllers interfere with each other. They each ‘see’ the others output as battery voltage, and reduce charge. “Gee, the battery is already at 13.4 - it’s full, so I’ll just float it….”

Best to run all your panels to one controller, which will manage charging your batteries. Btw - you should upgrade to the 100/30 controller to handle your power - it will charge at 30amps.

Others may have different insights, but I have a balmar 250 amp alternator and a victron multiplus 120amp charger. I do NOT get their combined output going into my bank, for the same reason.

AMatt