Fluctuating hum on multiplus

Kinda related to my other post here Stopping generator from pulsing while using washing machine or 3d printer .

I have an easysolar 24/3000/70 on a 24v system made of 8 190F batteries, fully offgrid.

I recently bought a 3d printer and while it’s running (most of the day), there is a distinct hum in the multi.
I am sure its normal but what worries me is that as soon as something else runs (water pump, vacuum) it starts fluctuating as well.

Will that ruin my equipment in the long run?
Is there a way to avoid the fluctuations?

Attached are a video of the multi with only the printer going, one while the pump is going as well and one of the pump “revving”.
Appreciate anyone that can help this noob out once again.
Cheers



@Deliotron
Hum is normal. There is a big transformer in the Multi.
Over the internet it is difficult to diagnose as there are many reasons.
When there is a pulsing in the inverter it could mean that the battery bank can’t supply surges to keep the transformer core saturated for pulses.

The pulsing pump is could be a pump or pump control problem. Unless for some reason there are fluctuations in the voltage from the inverter output or a something is messing with the sine wave. Or could also point tomi sufficient battery or battery related.

It can also point to inverter damage. Does it only happen with the specific load?

Yes it happens with the printer exclusively.
I don’t think it’s the pump alone as even a cheap led light I have in the home flickers.
Same flickering I had while running the old non inverter washing machine on passtrough to a generator (I now have substituted the washing machine with an inverter one and everything is smooth as).
Could be the printer messing with the sine wave? Very low on power consuption but If I add load to the system I still have that problem.
The printer is definitely the culpit here, wondering if there’s something I can put between the printer and the multi to help?
Thanks for your time

Pump is running fine when the printer is not on, batteries are healthy and can provide no problem.
Inverter output doesn’t flactuate when printer off

The sound is harmonic noise. The printer is probably changing the frequency and sine wave hence the pump speed change. (Mostly related to frequency)
Ideally you would switch your power source to a high frequency inverter with no transformer. You could isolate the printer power it from its own source.

Other option is to oversize your battery cable alot it will reduce the effect but definitely not eliminate it because of the physics involved

I might hook another inverter on my battery bank (after the smartshunt yes?) and use it only for the printer.
Someone else was suggesting to hook it to a ups to smooth the wave, will that work too?
Is not too bad as the pump runs sporadically but I’m wondering if it’s harming the multi in the long run?

A UPS wont smooth the wave to my knowlege.
And yes just put it as a load after the smart shunt. That way the system will keep the correct SOC.
As far as i know the humming wont damage anything. I have a few longer serving systems with strange noises that are load related and so far (more than 5 years) no issues to date.

When you are sizing your other little one, just be aware of its power factor. And size the inverter larger.

Thanks man, I’m reading into AVR ups but not sure they will work indeed and are not cheap.
Might dive deep and see if there’s a possibility there otherwise I’ll just hook the other inverter and dedicate power to printer/shed on the side. Probably best solution as doing so I can run the generator (non inverter, 2k little thing) to charge batteries in rainy days as for now if I do it will flactuate as well like crazy and walk down the hill lol. Appreciate your time bud, plenty to learn but surely keen! Cheers

Yea printer runs 200w barely but peaks 1kw when starting, I have a crude 2kw pure sine sitting there for emergencies that will do

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