cjhwhite7 avatar image
cjhwhite7 asked

AC Input Limit ignored when using Air Conditioning

24/5000 Quattro

Cerbo GX

Everything is updated with the latest firmware and I have tried a second new quattro to just test if the issue is in the unit itself.
When I set the input limit. It works fine, going over to powerassist when the amps increase. I have pulled between 600w-7500w of load with no issues using an array of heaters, lights and general loads like fridges. The inverter works fine with high loads and adding shore power and for the most part, works perfectly.

The boat had 3 different A/C units onboard. Each is about 1000-1500w

But, if I start 1 A/C module, there is a 50/50 chance that it keeps to the input current limit.

When I start the second A/C unit. No chance. It pulls a crap ton from shore power often blowing the fuse.


Input Limit set to 5 amps ~ 1100w and I'm using 1500w to run loads. Powerassist is happening on the diffence.

Start the 2 A/C units, Total load goes to 3000w, input power goes to 2700w completely ignoring the input limit until Iv turned most things off on the boat giving it a little time at low load.

Any ideas?

input current
2 |3000

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Jesse avatar image Jesse commented ·
I have seen others ask questions about the "assist current boost factor" in this context, but have yet to see any answers!! I suspect it might be relevant but am yet to find any useful explainer on how to adjust it without just guessing to see if it has any effect.

I have found the near instantaneous surge power required to start a single air con enough to completely overwhelm any input limit I set on my 12/1600 multi, and had wondered how things would behave in a setting with larger units. Your description is very interesting, please let us know if you find a solution.

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mt-geek avatar image mt-geek commented ·
check the neutrals. on my Quattro the amps are measured on the neutral leg if the shore power neutral and the neutral the quattro are connected together will cause that.
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1 Answer
Alexandra avatar image
Alexandra answered ·


Often items that have a poor power factor or triac based power regulation do this in the systems.

There are a few threads on this forum about how the input limit is ignored when compressors and ac units switch on.

Some soft starts for ac units also cause the issue as well so those need to be chosen wisely.

2 |3000

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