240V Mini-split....thoughts? - Page 3

miscrms · 01-03-2018, 08:00 PM

I know there are dc units out there, but the ones I’ve seen are $2k and the SEER rating wasn’t that great as I recall. A higher SEER unit with a good quality inverter might actually end up using less battery power.

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cadillackid · 01-03-2018, 08:12 PM

The big issue is that these units need high voltage to operate the compressor, if you are using 120 or 240, they have a good start , I still have a lab unit in my basement I’ll have to look and see but I think they rectify the incoming line to DC and then run it through the voltage converters .. the inefficiency with solar is that you are going from low volt DC to high volt AC only so it can be converted yet again..
The compressor runs on 3 phase variable frequency drive.
Christopher

cadillackid · 01-03-2018, 08:19 PM

Here are some pics of the outdoor unit driver boards.

Input from line

SPI bus interconnect between comtrols and VFD driver

Compressor VFD board. Compressor is the Blue black brown.

Full over view of the boards.

This is a circa 2010 chigo sources unit ( sold under grunaire name). Chigo makes units under dozens of brand names. This one is a 20 SEER unit.
Christopher

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miscrms · 01-03-2018, 11:43 PM

Agree CK, cool pics.

Direct dc drive should be more efficient in theory, but keep in mind the internal conversion efficiencies are already taken into account in both the dc and ac units.

Here’s the dc unit I had come across.
http://sharkaire.com/epages/fd93bb61...f7/Products/60

They don’t spec the SEER rating, but do give EER as 15.8 and power as 340w for 6000btu at a cost of $1600. That would seem to exceed the EER given though, which would be 380w for 6000 btu. At the same price a top of the line Fujitsu with SEER 33 / EER 18 will do 9000 btu on 500w. If inverter efficiency is 94% the Fujitsu will use 20w more to 38w less power per btu, and produce 50% more cooling for the same equipment cost. For another ~100w a 23 SEER 9000 btu Pioneer will give the same cooling for $799.

I keep going back and forth on the cost vs efficiency trade. The efficiency of some of these units is pretty amazing, but the cost is challenging. Even when you take the cost of upgrading the battery into account for the less efficient unit. I’m currently leaning toward the 22 SEER Pioneer 12000 btu units for $900. That’s kind of feeling like the sweet spot.

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cadillackid · 01-04-2018, 06:05 AM

The other piece though is how efficient are they when the condenser is under a bus.. in theory for cooling after the bus is parked for a long time it should be good as long as the unit doesn’t recite its own air. But what about those hours right after you park and the breeze is such all your engine heat ends up on the unit.. what are the watts.. also again max efficiency is at 80% or less of capacity. I swear I have the curves in a book somewhere.. so how people use them is a big factor in how many btu per watt you get real world.

Oh and I’m finished with the lab tests on those units so the ones in my basement can probably be had cheap esp if you live local and want to put it back together.
Ironically I’m going to move to Fujitsu if my current units die off or I get a new house
Christopher

miscrms · 01-04-2018, 10:15 AM

Very good points. I suspect that’s why some of those higher end units in particular are rated below their actual max output, so they can run peak efficiency at their rated output. That confused me at first, but makes sense.

Agree placement is important. I have a rear engine bus, and am leaning toward placing one outdoor unit on each side behind the front tires, with the air flow cross ways. Parking (or even driving) on pavement that’s been baking in the sun could still provide a pretty hot local environment for them though.

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cadillackid · 01-04-2018, 10:19 AM

I think it still remains to be seen how well (if) they will work when driving.. I domnt know if somewhereinusa has run his while driving or not. I know my units have over-current protection on the outdoor fan and will shut the unit down if that is exceeded.. so not sure how the wind of driving 65 MPH on the highway would affect the outdoor fan motor and whether theyll run or not.. I had one of mine get blocked by snow in winter and when it tried to turn on, tossed an error code and shut off.. (which told my computer to throw my home system, into gas heat mode)..
-Cnristopher

Serengeti · 01-04-2018, 09:04 PM

Is @somewhereinusa still active on here? I could really learn first hand experience from him. Sometimes the number crunching does not come close to real life experience. His front installation is also a data source.

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dan-fox · 01-05-2018, 04:42 PM

Chris, you said (more than once IIRC) that the motors inside the minisplits are 3 phase driven by VFDs. Do you think that that subsystem could be scraped out of one of those that had died for different reasons? And how powerful do you think those motors might be? 1 hp? 2?

The build-your-own-tools community just loves to find a cheap source of variable speed motors and the current gold standard is to get a DC motor out of an electric exercise treadmill and either build or buy a controller. This is popular enough that folks who used to give their old treadmill away now sell them for parts on C'list. Not that it's not a good thing to be able to put together a 2 hp VF motor for $200, but free is better.

cadillackid · 01-05-2018, 06:34 PM

Quote:

Originally Posted by dan-fox

Chris, you said (more than once IIRC) that the motors inside the minisplits are 3 phase driven by VFDs. Do you think that that subsystem could be scraped out of one of those that had died for different reasons? And how powerful do you think those motors might be? 1 hp? 2?

The build-your-own-tools community just loves to find a cheap source of variable speed motors and the current gold standard is to get a DC motor out of an electric exercise treadmill and either build or buy a controller. This is popular enough that folks who used to give their old treadmill away now sell them for parts on C'list. Not that it's not a good thing to be able to put together a 2 hp VF motor for $200, but free is better.

the compressors are sealed units.. typically what ive found is that A/C compressor motors are cooled by the return refrigerant flow.. so not sure what kind of use you would get if you cut open the compressor and sniped the motor im not sure it would do you much good.. seems pretrty specialized... the VFD board? maybe if you can determine the protocol it uses to run.. its not a standard 0-10 volt or 0-2 amp signal.. the boards are all made by chines companies.. sometimes in house by the unit manufacturer.. there are 100 different nameplates on minisplits.. but theres only a few companies in china that make the discount brands.. rest is OEM.. there are lots of options each OEM can spec on their boards and units..

some of the mainstream manufacturers are mucn more controlled in the manufcacture of their units.. Fujitsu and Mitsubishi are a couple..
-Christopher

dan-fox · 01-08-2018, 11:52 AM

Quote:

Originally Posted by cadillackid

the compressors are sealed units.. typically what ive found is that A/C compressor motors are cooled by the return refrigerant flow.. so not sure what kind of use you would get if you cut open the compressor and sniped the motor im not sure it would do you much good.. seems pretrty specialized... the VFD board? maybe if you can determine the protocol it uses to run.. its not a standard 0-10 volt or 0-2 amp signal.. the boards are all made by chines companies.. sometimes in house by the unit manufacturer.. there are 100 different nameplates on minisplits.. but theres only a few companies in china that make the discount brands.. rest is OEM.. there are lots of options each OEM can spec on their boards and units..

some of the mainstream manufacturers are mucn more controlled in the manufcacture of their units.. Fujitsu and Mitsubishi are a couple..
-Christopher

Cutting a sealed unit open probably isn't worth it, particularly when you add the hassle of trying to reverse engineer the control circuitry. Thanks anyway though.

amrick_nz · 01-12-2018, 10:55 PM

where are these alternators at that price ?????

john61ct · 01-13-2018, 04:06 AM

Quoting would help

amrick_nz · 01-13-2018, 07:39 PM

Quote:

Originally Posted by john61ct

Don't even think about batteries much less solar with loads that big.

Remember a 3500W load when running may pull a surge double that when starting up. Check out starting capacitors, may help a bit.

Robust grid power, or a very large, very heavy AC generator is the normal way to go.

There are CEN alternators that put out 400+ amps @ 24V while driving, designed for military vehicles, excellent value at $450+ NOS.

But a big enough, good quality inverter to get that to 240VAC will cost as much as many buses.

where are these alternators ... $450 + NOS ... im in australia so what is nos?

Twigg · 01-13-2018, 07:50 PM

Quote:

Originally Posted by amrick_nz

where are these alternators ... $450 + NOS ... im in australia so what is nos?

New, Old Stock.

john61ct · 01-14-2018, 08:36 AM

I don't know if C.E.N. is imported into Australia, best to stick to brands that are, for parts and assistance with service. Leece Neville, Delco Remy are other brands used in NA market.

Look for surplus from military, agriculture, construction, marine, mining or emergency services, any vehicles that have large power needs while not under way, the propulsion engine is just high-idling.

If you have to order from the US shipping will add a lot to the cost, these HO units can weigh like 60kg.

Rawlings · 08-22-2019, 02:17 PM

Hi guys I am jumping on this thread as we are getting ready to size our off grid system and we are going to use a mini split from Pioneer. the 220 volt may give issues when you go into a camp with 30 amp service as that only provides 1 hot leg..you will need to hack the panel and jumper the 1 leg to the other side of panel but that may lead to power issues :s not entirely sure.

Anyways on our side we are looking to run a pioneer mini split 110volt 12000 btu off grid. We are looking at the following system

Tesla Battery 5.2 KWH $1019

Peimar 310 watt panels x 8 for 2480 watts of solar = $1492

Aim 3000 watt 24 volt inverter $1074

Are we safe to assume a system this size will be able to turn this Mini split on? Is this mini split enough for a 1978 crown bus 35 footer.

How long will the battery keep AC on during the night?

I am thinking 110volt times 20amp circuit required is 2200watts for the Pioneer per hour however I know its not gonna be cranking 20 amps every second... So am I safe to assume it cranks more like 10-12 amps?

Has anyone done something like this? We are willing to have a generator as backup for days with low sun. But would the battery be enough to keep the AC on for the night?

Booyah45828 · 08-22-2019, 03:03 PM

Quote:

Originally Posted by Rawlings

Hi guys I am jumping on this thread as we are getting ready to size our off grid system and we are going to use a mini split from Pioneer. the 220 volt may give issues when you go into a camp with 30 amp service as that only provides 1 hot leg..you will need to hack the panel and jumper the 1 leg to the other side of panel but that may lead to power issues :s not entirely sure.

Yeah, don't do that.

A typical 30 amp camper plug will have 1-120 volt hot, 1-neutral, and 1-ground. There's no way for you to get 240 out of that circuit.

A typical 50 amp plug will have 2-120 volt hots, 1-neutral, and 1-ground. This plug you can get 120 volts by going from a hot to a neutral, or 240 by using both hots.

Hopefully this picture explains it better.

As far as the rest of your question goes. You'll have to do the math. Mini-splits are super efficient, and like you assumed, have much lower power draw after initial startup. As far as what it consumes while running all depends on the size of the room and how well insulated it is. If nobody has any direct experience, I would suggest you install the unit and your insulation, see how much it draws over a time period, and then size your solar, battery bank, and inverter accordingly.

o1marc · 08-22-2019, 04:22 PM

It will turn on with no issues at all. I have a 12kBTU minsplit running off 600watts of panels and 430ah in batteires with a 1200w inverter. The problem will be how long you can run it before depleteing the batteries.

Rawlings · 08-22-2019, 06:15 PM

Quote:

Originally Posted by o1marc

It will turn on with no issues at all. I have a 12kBTU minsplit running off 600watts of panels and 430ah in batteires with a 1200w inverter. The problem will be how long you can run it before depleteing the batteries.

These Tesla batteries are 5.7kwh what would that be in amp hours and how long would that give your 12k btu ?

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