Electric Compressor on boat, changing Single Phase to 3 Phase

[2ge]

Hi all,

I am in process of buying small electric dive compressor suitable on 47 foot catamaran, looking on Bauer company either Junior II, Oceanus, or Poseidon PE100...I dont want to buy new one, so looking in Europe for 2nd hands - not too old..., and there are some good deals for Single Phase compressors, but if I understand correctly there is problem with high load in begging to start them, I checked soft start solutions, but it seems it is better to go 3 Phase and VFD converter.

It would be ideal to power it from batteries, I like how this guy did this:

Question is - how hard it is change Single Phase motor to Three Phase motor on compressor ? How much it would cost approx and if it is not better way to go with Soft Start solution then.

For now, there is no genset on board (I will buy one, looking for 3kw), just batteries

Thanks for recommendations.

 

[CycleCat]

I used to work at a rural winery that only had single phase power but we needed to use one of these to simulate 3-phase for some of the larger equipment.

Ronk converter

 

[-JD-]

If you are going to be running off of a battery bank, you may be better of going directly to a DC input controller w/ 3phase-brushless motor setup. With the development of EV/E-Boat tech, stuff is becoming more available and it saves the cost and inefficiencies of multiple power conversion and control steps. I see 5kW sets going for < $2000 US sold for sailboat drives and you could likely get away with something in the 3kW range for those compressors.

There are basic 3-5kW kits going for < $1100 US on Amazon from Golden-Motor which also sells e-drive outboards: www.goldenmotor.com
3KW 48V 4000RPM Fan Cooling BLDC Motor and Controller Electric Motorbike Conversion Kit
48V 5KW 4000RPM Fan Cooling Motor with Controller for E-motorcycle Conversion (HPM5000A)

First (big) question is what type of bank you have. A BIG 36V (realistically 48V) is going to be the minimum.

 

[100days-a-year]

Alternator will unlikely be able to keep up with demand.
Figure roughly 1 hp per cfm.
745 watts continuous per hp.
Best if the battery bank and compressor are close to each other.

 

[2ge]

thanks for answers. There are 12.8V LiFePo4 batteries, 100 Ah, 1280Wh with max Discharge current 100A from Victron - it is not a big problem put another, if 4 batteries will be not enough. I am going to replace inverter, now it is Victron 1600VA, max 70 AMP, for at least 3kw inverter.

Going via DC way is really interesting, I understand those conversions losing quite a lot of percent of power, not sure how it is with VFD. But I never saw compressor running on DC power on boat, that would be nice to know more details.

Anyway, it seems seller can change 2 Phase to 3 Phase on compressor, so via VFD be it.

 

[BRT]

thanks for answers. There are 12.8V LiFePo4 batteries, 100 Ah, 1280Wh with max Discharge current 100A from Victron - it is not a big problem put another, if 4 batteries will be not enough. I am going to replace inverter, now it is Victron 1600VA, max 70 AMP, for at least 3kw inverter.

Going via DC way is really interesting, I understand those conversions losing quite a lot of percent of power, not sure how it is with VFD. But I never saw compressor running on DC power on boat, that would be nice to know more details.

Anyway, it seems seller can change 2 Phase to 3 Phase on compressor, so via VFD be it.

Please tell us how it works when you are done!

 

[happy-diver]

The Oceanus is so much faster for less noise

 

[Angelo Farina]

I think you need to work out some energy balance calculations.
A compressor usually requires a continuous power of 2-3 kW and sucks 4-5 cubic meters of air in one hour, which are enough for a couples of tanks, if not entirely empty.
For 4 tanks it runs two hours, hence requiring something as 5 kWh of energy.
Apart the conversion lossess, if you use LiFePO4 batteries storing 1250 Wh each, you need 4 of them, possibly costing more than the compressor!
Here at home I have an LG battery storing 10 kWh, which costs 6000 eur. And you have to add the inverter....
Simple solution: no energy conversion, just use a Briggs & Stratton gasoline engine, or perhaps an Honda if you like Japanese engines...
Driving directly the compressor.
Just take care that the engine's exhaust is always downwind the compressor's intake.
That is the solution employed on most boats...

 

[-JD-]

Even with the upgraded inverter you would be likely to be overextend.

@Angelo Farina nailed it.
Petroleum - small gas or diesel is your best bet to keep the cost reasonable if you want portable.
Other possible fixed option is to drive off of the main diesels somehow ..

 

[clownfishsydney]

No possibility that you can run off batteries. Change to petrol motor and all okay. Simple, cheap.