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@JustMurph I think in some ways you have answered your own question there. You already know a bigger capacity generator is needed. Also ambient temperatures will mean you have to de-rate both the inverter and battery capabilities. Motors are a particularly interesting load for any power source as the KvA rating can be massive especially if the power factor is not great due to age and other factors.

In any case at 8000Va from a 24V battery the battery alone woul have to be able to deliver over 330A of power. I dont know any that can do that without issue at 25 degrees C never mind higher. Possibly consider a 48V system. The Victron can handle quite a surge current for short bursts if the battery can deliver, but go with one that will handle the load under operating temperature de-rating.

Hello Justin

The Multiplus 5000 alone could not start our compressor (Bavaria FUN, allmost identical to the Bauer Junior). Together with our generator FischerPanda 5000i Neo it works fine. Once running, the generator can handle the load. Neither the generator nor the Inverter can start it on its own.

Kind regards
Botnic

As a quick update, we've been bench testing my system with our 2.2kW single phase shop compressor (while waiting for the Bauer). Quite impressively the Multiplus managed to start the compressor every time, both unloaded and loaded and even when fully heat soaked. This compressor does have a start capacitor on it as standard, which I believe the bauer doesn't. This is where the Sure Start from Hyper Enginering will help.

We should have the Bauer this week and will test some more.

Well, I have a clear answer now, no, you cannot run a Bauer Junior on a 5kW Multiplus. It turns out the Hyper Engineering made a big mistake when they originally told me they'd tested this combination with their Sure Start on a 5kW inverter.....and now tell me the smallest they tested on was 7.5kW.

Big omission guys. I now have a massively oversized inverter and a compressor with a hacked up terminal box that I can't run.

Anyway, moving on to plan B. 3 phase motor and a 1 to 3 phase VFD.

@JustMurph I'm converting my existing Bauer II Jr to electric as part of a LiPo upgrade. I've been pondering the exact issues you've faced - and with the same products. Are you you still chipping away at that problem? I"m keen to find out how it turned out.

Interesting post, but still not sure about what we should use, please, help !

We are a van conversion company. One of our next customers is a scuba diver and will be off grid with I suppose 370W solar panel. His Sprinter 2019 doesn't have a smart alternator. He wants to have a compressor in his van to fill the Oxygen tank. He wants Victron material with about 300W solar panel and a relay charger. He will have a hook up possibility but won't have regular access. Traveling in Africa and Scotland ... extreme temperature.

Here is the link for the compressor that would run for about 30min every 2-3 days.

I emailed the company to have more info regarding the starting power, here tare the different answers I received.

“The start up current for the MCH6, 2.2kW 50hZ compressor is approximately 66 Amps

The compressor must be free of residue pressure, the gauge must read 0 bar before start up otherwise AMPS could be more”

“The answer is 83 Amps.

At the start, the electric motors need a variable amount of Ampere from 3 to over 5 times those written on the plate.

It depends on the type of engine and where you get the electrical power from.

I'll give you an example:

3kw 16Ampere in the house and the compressor is able to start and work.

However, if you have to use a power generator, it must be at least 8KVA otherwise it won't start.”

In top of this compressor,

electric induction hob, 12V fridge 100L, lights, laptop 4h/day, phone charging, standard 12v lights.

I don’t know which type of system and batteries he should use ?

Thanks for advising me. XX

Cecile

@Vanpuravida

2.2kW is the same size as my compressor, so you'll have the same issues trying to start it. The ultimate solution is a DC motor conversion, but that's not a quick or simple exercise. The easiest electric solution is pretty much what I've done. You'll need the three phase motor version of the compressor (or to convert it - easy) and to then run it with a small single phase to three phase VSD (variable speed drive). You would run this from the inverter (minimum of 3kW continuous output @ ambient temp).

Batteries will need to be lithium. Lead acid can't handle the currents. A fill on my system uses about 1kwh, so you'll need to factor this into the battery sizing, seeing as most of the power will come from the batteries. That's a fair chunk of the days generation from a 300W solar panel, so I'd recommend getting a bit more solar up there if possible. You can do up to 600W in a single panel (2.4m) these days, or maybe a pair of 400W 1.7m panels turned sideways.

I'd be going at least 400AH for the battery bank.

Hi Justin

We are trying to run a similar setup but are having some issues.

Can you please specify what VFD you are using?

And do you have any fluctuating in Voltage or amp, and if so how much?

Best regards Thorsten

I just got my Bauer Jr running onboard. It took changing to a 3ph motor, (same frame, 2.2kw), and a Siemens V20 inverter, 1 phase to 3 phase. Standard motor info for setup, ramp time 5 sec.

Starts right up, heavy draw on the DC side, but w/ Lithium - solar - engine alternator running, we are filling away from the dock.

Thanks to Justin for pointing me in the right direction! Cheers