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corvus avatar image
corvus asked

Power assist with 30 amp RV

The manual suggests that wiring to my power distribution should be upgraded because of the power boost feature. However, the manual only addresses 50 amp services. I have a 30 amp RV, so…from what I can tell I should use 6AWG wire from the multiplus to the the power distribution panel, and then upgrade the breaker there to handle any additional load from the power boost feature. Is there any documentation about using power boost in a 30 amp camper?

powerassist
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blutow avatar image blutow commented ·

Crazy, I just logged on looking for an answer to the same question, exact same situation. I will limit shore power to 30a, but it's not clear in the manual how much power assist will add. I have a victron 12/3000 120v inverter. The following is what is stated in the manual:

"With its PowerAssist feature the Multi can add up to 3kVA (that is 3000 / 230 = 13A) to the output during periods of peak power requirement. Together with a maximum input current of 50A this means that the output can supply up to 50 + 13 = 63A. ".

This looks like it might be a "cut and paste" typo from the 230v version of the multi, because 3000/230 doesn't make sense to me for a 120v unit. If the 12/3000 120v unit can also do power assist up to 3000kVA, wouldn't the calculation be 3000/120v = 25a of assist? That sounds pretty extreme though if it could pass through 50a and assist another 25a for a total of 75a. If limiting to shore power of 30a, that would mean output on AC1 of 55a, which I think would be fine with 6awg, but too much for 8awg. I'm not sure what the difference is between 3000kVA vs. 3000watts, so maybe I'm not thinking right on this and my math is flawed.

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Alexandra avatar image
Alexandra answered ·

@Corvus

Always use the recommended wiring size for the inverter or components being installed.

The power boost (I assume you are referring to power assist) uses battery/solar power to add to the incoming power for loads.

See this video for more information.

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blutow avatar image blutow commented ·
I don't see any wire size recommendations in the manual for the AC output, just the main DC inputs. The video link doesn't work for me.
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Alexandra avatar image Alexandra ♦ blutow commented ·
https://youtu.be/Odo6LNSjykQ

If you look on the Victron channel there is one with the title

Did you Know - How to add power to a limited shore power hook up

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kevgermany answered ·

Watts/kVA. Look on kVA as max watts that can be drawn, depending on the type of load, watts is usually less. It's a 'feature' of AC.

My reading of power assist is inverter capacity plus AC in. Afik same for 120V.

Size the cables for the full current. Plenty of calculators on line. If there are breakers in your unit, check what they're rated at,

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blutow avatar image blutow commented ·
I guess that could be right, but 75a on a single wire/circuit at 120v is kind of nuts. The biggest 120v single pole breaker I've seen is 60a and that that would be massive wire. Since I'm limiting to 30a shore power, it's "only" 55a, but that's still a big 120v load. I don't think I'll ever draw that much, but I guess I'll go with 6 awg and a 50a or 60a breaker. 60a breaker on 6awg is pushing the limits, so might just need to limit to 50 and it should be rare I ever exceed that.
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corvus avatar image
corvus answered ·

@tmartin000 you answered what I was really getting at. For the record, I'm not really interested in getting 50 amps. Two devices often does not exceed 30 amps, but it does often exceed the 80% of a 30 amp breaker. I will look further into my particular power distribution.

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tmartin000 avatar image
tmartin000 answered ·

Who says that extra 50a wouldn't be less than 30 seconds and cause no harm? Likely (in my 30a RV, it would be only short durations....air conditioner and a 1 min coffee pot, most likely...I used 6/3 and do not feel short bouts of 50a use.

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