Jared Wellman avatar image

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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2 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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Mike Dorsett avatar image
Mike Dorsett answered ·

good to have some detail on how this behaves.

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