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derrick thomas asked

Same old issue with power assist

@Guy Stewart (Victron Community Manager) I have seen several topics or questions on the same issue with no solutions regarding power assist. I have 2 multiplus2 2x120 24/3000 in parallel in an RV. Input current limit set @ 18.6 (the lowest it can go with power assist on) with loads @18.2 the inverters are only pulling 10amp from shore with the rest being pulled from batteries. I let it go for several minutes in hopes that it would level out somewhere closer to the input current limit but it stays at 10amp. Obviously this is not optimal as it will just continue to drain the battery bank. I would expect to see maybe a few amps difference between the input limit setting and the current drawn for a safety margin but this seems very excessive, about 46% if my math is close. This seems to be an issue that has been brought up repeatedly with no real answer or solution. Is victron working on this?


Both inverters are running 498 firmware, imbalance on the ac side is within about 15 watts and DC side within 2 amps. Power assist and dynamic current limiter are ticked, weak ac input is not.

power assist
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klim8skeptic avatar image klim8skeptic ♦ commented ·

Repeat with Dynamic Current limit un-ticked?

dynamic-current-limit.png


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dynamic-current-limit.png (89.5 KiB)
derrick thomas avatar image derrick thomas klim8skeptic ♦ commented ·
I fail to see how this would help? The dynamic current limiter only has a temporary effect when a load is initially introduced, then the load is transfered to the ac input up to the current limit setting.
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Alexandra avatar image Alexandra ♦ derrick thomas commented ·
@derrick thomas

Since set up and installs. Ary so much replication is not always easy.

What I have seen in some systems wiring has alot of influence on the system. Wiring size length and connections has an effect on the resistance in a system.

So if your incoming has high resistance this can be a cause of the inout being lower. So can voltage.

I have a 12/1600 in a mobile set up. I have seen the extension used for charging up (have a 7m 4mm one and a 15m 2.5mm one) affects how much it will pull and use. No other settings changed.

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derrick thomas avatar image derrick thomas Alexandra ♦ commented ·
From the 200amp service connection is run 60 feet of 2 awg to a 50 amp outlet, then a 25 foot 6 awg 50amp shore cord to the ats, and then 12 feet of 6awg to the multis. Voltage and frequencies are very stable even under higher loads. It acts the same when running from the onboard generator as well. My old hybrid magnum always worked flawlessly under the same conditions in the same location. It seems to be something to do with the multis logic.
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1 Answer
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derrick thomas answered ·

I think I found my own answer. After further testing it appears that the multis combined input l1 and l2 while in power assist mode even though they were connected to split phase 240 input. This was unexpected behavior but it is repeatable. When connected to single phase 120 the multis are mostly within an amp or two of the current limit setting when power assist is active. That seems right. But when connected to split phase input again it seems to be combining l1 and l2 inputs and holding the input current to this limit, instead of the limit applying to each leg individually. I realize power assist only functions on l1 but I would expect the current limit to be applied separately while in split phase.

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