Jared Wellman avatar image
Jared Wellman asked

Power Assist Boost Factor and overloading MutiPlus

I have a 12/3000/120 MultiPlus and I'm trying to understand some Overload issues that I'm experiencing and wondering if the Boost Factor is potentially causing the issue.

Setup is as follows:
Input Limit: 30A
Power Assist: Enabled
Boost Factor: 2.0
UPS: Disabled
Input Power: 4500W Inverter Generator (3800W running)

I've noticed when a large load comes online that the MP will overload and disconnect. I also get an error from my EMS that the voltage has gone "out of spec" (sadly it doesn't tell me which way). What is interesting is that the load is under the 30A input limit and can easily be handled by the generator alone. I'm wondering if the MultiPlus is "preparing" to power assist approximately 7200W (Boost Factor * Input Limit) and causing the overload itself?

If I set the MP to "Charger Only" the Generator can handle these loads just fine. So it seems to be something specific to Power Assist causing the issue. I do plan on turning down the Input Current and running this same test to see if Power Assist successfully assists without disconnecting but I haven't ran this test yet.

Should I lower the Boost Factor down to 1 (or maybe even lower) to stay within the 3000W that the MP can provide? Is there anyway to configure this so that it is not reliant on the input limit? For instance if I'm connected to 15A power I would want a higher boost factor.

Thank you!

MultiPlus Quattro Inverter Chargerpowerassist
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3 Answers
Jared Wellman avatar image
Jared Wellman answered ·

So answering this myself.

Basically "Yes". The MultiPlus was actually overloading itself because of the Boost Factor.

I set the input current to 15A with the generator connected and started both AC units no problem with the MultiPlus happily filling the gap:

However I will primarily be on 30 or 50A power so the main goal was to figure this out when on a 30A circuit. After finally understanding what the boost factor does it was pretty apparently that setting it to `2.0` and having the input be 30A was almost certainly causing the MultiPlus to overload. 2nd post explains it:

Basically the `boost factor` is how much power the MP will prepare when Power Assist is engaged. So with a boost factor of 2 and an input of 30A, this is 60A of power...or 7200W, which is substantially more than the MultiPlus 12/3000/120 I have is capable of. Thus any load over the 30A input limit would send the MultiPlus into an overload situation when it tried to "spin up" that much power.

I ended up setting the Boost Factor to 0.8 since
(Input Limit) * (Boost Factor) * (AC Voltage) = MP Boost Wattage Requirement
30A * 0.8 * 120 = 2880W


So this will work for 30A but will likely not be adequate for 15A input limit. Honestly I feel that the "Boost Factor" is a poor way of setting this up. Ideally the MP should handle this internally without the need for configuration and it seems very odd that it is related to the input current. If the MP can supply 3000W then it should prepare 3000W for the Power Assist operation. Or maybe I'm just missing why this has to be related to the Input Current? It's also very frustrating as if I move to a location with 15A power or run off of a smaller generator that I now have to reconfigure the MultiPlus.


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1 comment
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What's the actual *total* power output of this MP model boosting the AC shore power via the PowerAssist mode? Is it the rated 3000W maximum output, or is it 3000W added to the input power?

I think you're the first person to answer this question for me, albeit indirectly. The total output power is limited by the MP output rating, in this case, 3000W. PowerAssist does not *add* 3000W additional power AC input shore power. I was hoping that I could use the MP to boost, say a 2000W AC power input and *additional* 3000W, to 5000W total. But this doesn't appear the be the case. The inverter can only handle *up to* 3000W when the AC input shore power is less than 3000W.

So, the PowerAssist boost factor is a multiplier factor applied to the AC input current, but is limited to the maximum rated power output of the MP inverter model? And if that total current exceeds the inverter's rating, the inverter will shut down with an error.

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Mike Dorsett avatar image
Mike Dorsett answered ·

good to have some detail on how this behaves.

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Paul B avatar image
Paul B answered ·

What you may find is that you are going over the MAX passthrough limit there are two versions a 16amp pass through and a 50amp passthrough versions of the multiplus 3000

if the load goes over the max figure that multiplus will disconnect the gen

Some motors have very large startup currents that push the amps over the max limits

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