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derrick thomas avatar image
derrick thomas asked

Not getting full DC charger output from parallel mp2

As the title suggests I am not seeing full DC charging output from parallel multiplus 2's. I have 2 MP2 24-3000-70-50 2x120 in parallel. Ac input feeds from the ac in junction box are the same size and length, as are the ac output leads to the junction box. Both ac in and out are 12/4, the manual is very clear about not oversizing the ac wiring for the purpose of balancing between the 2 multi's. I have checked and the multi's are within less than .5 amps of each other under various load conditions. The DC side is fed from a lynx distributor with same size and length wire going to both units. (0000 wire connects 400ah lifepo4 battery bank to the lynx, and 0 connects each inverter to the lynx. Initially each inverter was connected to the lynx with 2guage and I thought to try different size when I wasn't seeing full DC output but no change) everything is connected to a cerbo and I also have a smart shunt. I am only seeing 120 amps combined from the inverters in bulk. I have confirmed that each inverter will put out the full 70 amps in stand alone. The battery bank can take 1c charging (the full 400). If I start the RV and the alternator starts to supplement the inverter charging the batteries will take way over 140 so I don't believe it is a limitation anywhere in the system. DVCC is enabled but these are self managed batteries so no bms connected to cerbo and only shared voltage and current are enabled in DVCC. Max charge current is set to 250.

Unfortunately my clamp meter only reads ac amps and not DC so I can't tell if both inverters are throttled back equally on charging or not. Oh and the firmware is 497. Any ideas? Or is this one of those "it is what it is" situations? Same behavior on shore power and generator.

battery chargingmultiplus in parallelDVCC
2 |3000

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2 Answers
Adam avatar image
Adam answered ·

Make sure that 70 amps is set in the charger tab in VE config on both multi's , sometimes , particulary with the Quattro 15's the charger tabs from default is set lower than 200amp usually 150.

might be worth a shot to check

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derrick thomas avatar image derrick thomas commented ·
Yes have verified 70 amps is set in both multi's in the charger tab
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nickdb avatar image
nickdb answered ·

You really need to check it with a meter, also worth checking that you don't have a current limit set in DVCC.

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derrick thomas avatar image derrick thomas commented ·
Current limit is not set in DVCC. I thought for some reason I had set it to 250 but upon rechecking it is not enabled. Only thing active in DVCC is max charge voltage which is the same as absorption, and svs and scs.
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Adam avatar image Adam derrick thomas commented ·

Maybe try removing the max charge voltage in DVCC temporarily to see if it makes any difference? maybe also try toggling shared voltage sense and current sense off to see if that changes thing. Even can try turnig off DVCC and see what happens as long as you have charge voltages set correct in the equiptment for your.

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