Tips on using a Honda 2KW Briefcase to run a Mini Split AC

Surfpath
Surfpath Solar Expert Posts: 468 ✭✭✭
in Off Grid Solar & Battery Systems #1
Hello there,
I am advising someone who would like to air condition a couple of guest bedrooms (~350-375 sq feet) over a period of 10-14 days this Summer using their generator (a 230v Honda EU briefcase). They are thinking of installing a Samsung 12k btu mini-split inverter AC (I have not got my hands on the specs for this 230v unit yet). They anticipate running the AC for about 8 hours a night.

After this 14 day period (when their guests leave) they plan to periodically use the AC, but only on still hot days. Incidentally, they do have an off-grid PV system, but their battery bank and panels would not enough to handle the AC's night time draw down at this point.

The rooms are concrete block construction (ie fairly well insulated). The windows will probably need additional insulation.

The specs for their genny:
Honda EU20i
Rated Watts 1600
Voltage 230V
Fuel Tank Capacity 4.1 Ltrs
Running Time 10.5 hours @ 1/4 load

I have read many of the useful mini-split threads here, so I know that it's possible to do this. But are there any specific tips or suggestions I can pass on to them about running their generator during this 14 day time? I know many here have Honda briefcases so I thought I'd seek your advice.
  • Will the Genny's gas tank be big enough to make the 8 hrs?
  • Should they flip the switch to ECO?
  • Are there any other tips that you'd suggest?
Many thanks
SP

ps. Vic, no word on my own generator still :-(
Outback Flexpower 1 (FM80, VFX3048E-230v, Mate, FlexNetDC) 2,730watts of "Grid-type" PV, 370 AmpHrs Trojan RE-B's, Honda 2000 watt genny, 100% off grid.
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Comments

  • vtmaps
    vtmaps Solar Expert Posts: 3,741 ✭✭✭✭
    #2
    Re: Tips on using a Honda 2KW Briefcase to run a Mini Split AC
    Surfpath wrote: »
    • Will the Genny's gas tank be big enough to make the 8 hrs?
    • Should they flip the switch to ECO?
    • Are there any other tips that you'd suggest?

    If it doesn't last 8 hours you can easily hook up one of the several inexpensive auxiliary fuel tanks for it. The honda is perfect for this type of aux fuel tank because it will suck the fuel out of the aux tank.

    As for the eco switch, try it and see. if it works ok, definitely use it. Some of the minisplits have inverter controlled motors and should be soft enough start for the eco throttle to work.

    --vtMaps

    btw, your genny has been out of action for quite some time... I take it you're managing OK without it? If I recall, weren't you going to have a hydro resource?
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
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  • Surfpath
    Surfpath Solar Expert Posts: 468 ✭✭✭
    #3
    Re: Tips on using a Honda 2KW Briefcase to run a Mini Split AC

    I have been absolutely fine without my generator. Turns out PV is all I have and need.
    Thanks for the tips on this question. More are welcome.
    Outback Flexpower 1 (FM80, VFX3048E-230v, Mate, FlexNetDC) 2,730watts of "Grid-type" PV, 370 AmpHrs Trojan RE-B's, Honda 2000 watt genny, 100% off grid.
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  • jonr
    jonr Solar Expert Posts: 1,386 ✭✭✭✭
    #4
    Re: Tips on using a Honda 2KW Briefcase to run a Mini Split AC
    Surfpath wrote: »
    The rooms are concrete block construction (ie fairly well insulated).

    Block construction is typically poorly insulated. On top of that, it has high thermal mass, which means that if you want to only cool it for part of the day, there is a lot of thermal inertia to overcome.

    Also verify that the room is very well air sealed. Latent load is significant and high humidity is uncomfortable.

    I am available for custom hardware/firmware development

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  • Blackcherry04
    Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    #5
    Re: Tips on using a Honda 2KW Briefcase to run a Mini Split AC

    As VT said, you'll have to see if it will run with the ECO throttle on and cycle the compressor without faulting. The best way is to have the A/C powered by a Inverter with Generator Support available and have the generator connected on pass through. The idle output of the Honda is about 400 W anytime it's running. With a A/C on it alone it's just pulling the fan off cycle ( 50 - 100 W ), the rest of that power is just wasted. By having it on a Inverter with pass through you can charge the batteries during the compressor off cycle. Even with small batteries and small PV you can do a lot with good management and the right equipment.

    If you don't have a Inverter with Gen Support your still better off using it with a stand alone charger and using it as a charging source @ about 50 % output of the Honda. At night the compressor cycles don't justify keeping it on the Generator alone even with the conversion losses. A Honda EU running with the ECO throttle off and full load gets about 2.7 hrs per gallon and unloaded I don't know how much that would be, it's variable. The only way to use it's fuel savings is to use the ECO throttle ON and load it less than 700-800 watts, above that you won't save much with a constant load.
    .
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  • Surfpath
    Surfpath Solar Expert Posts: 468 ✭✭✭
    #6
    Re: Tips on using a Honda 2KW Briefcase to run a Mini Split AC
    Blackcherry04 wrote: »
    If you don't have a Inverter with Gen Support your still better off using it with a stand alone charger and using it as a charging source @ about 50 % output of the Honda.

    Thanks for the reply. Nope, no apparent reliable inverter with gen support (it's a long story and another thread). Also, no stand alone charger. But I understand how those could be beneficial.

    Thanks for the figures on the idle output (400w), ECO running (ie. < 800w), and full load fuel consumption (2.7 gals - seems high, even for full load).

    Sounds like it's be a bit of a fuel draining exercise, but perhaps for just the 2 weeks it'll be OK.

    I am actually working with them on a different tack now....

    1. Evaluating their loads (for an off grid house they have a hog of a fridge. I measured it at 2.50Kwh/d).
    2. Selling/replacing appliances (such as the fridge) and reducing loads in general.
    3. Running good, low energy use fans instead of AC.
    We shall see.

    Out of curiosity, (while directly hooked up to the genny) what are the consequences of fuel running out of the Honda 'briefcase' while the AC is compressing? Are there any potential adverse consequences? Just curious myself.
    8)
    Outback Flexpower 1 (FM80, VFX3048E-230v, Mate, FlexNetDC) 2,730watts of "Grid-type" PV, 370 AmpHrs Trojan RE-B's, Honda 2000 watt genny, 100% off grid.
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  • Blackcherry04
    Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    #7
    Re: Tips on using a Honda 2KW Briefcase to run a Mini Split AC
    Surfpath wrote: »
    Thanks for the reply. Nope, no apparent reliable inverter with gen support (it's a long story and another thread). Also, no stand alone charger. But I understand how those could be beneficial.

    Thanks for the figures on the idle output (400w), ECO running (ie. < 800w), and full load fuel consumption (2.7 gals - seems high, even for full load).

    Sounds like it's be a bit of a fuel draining exercise, but perhaps for just the 2 weeks it'll be OK.

    I am actually working with them on a different tack now....

    1. Evaluating their loads (for an off grid house they have a hog of a fridge. I measured it at 2.50Kwh/d).
    2. Selling/replacing appliances (such as the fridge) and reducing loads in general.
    3. Running good, low energy use fans instead of AC.
    We shall see.

    Out of curiosity, (while directly hooked up to the genny) what are the consequences of fuel running out of the Honda 'briefcase' while the AC is compressing? Are there any potential adverse consequences? Just curious myself.
    8)
    The consumption is full load gets about 2.7 hrs per gallon is what I get, some may get more, what you stated was backwards. If you run out of fuel, the generator will stop, I can't see where it would hurt anything. In a Inverter Generator once the DC was not powering it the inverter would drop out, no wind down.

    As was stated you can hook up a auxiliary gas tank to extend it's run time, I use 3 gallon tanks on mine/

    Here is some Internet results on fuel use.

    1,600 watt load: Run time 2.97 hours/gallon. 4.75 kWh/gallon, RPM = 4,300
    465 watt load: Run time 8.92 hours/gallon. 4.15 kWh/gallon, RPM = 3060
    555 watt load: Run time 8.06 hours/gallon. 4.47 kWh/gallon, RPM = 3150
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #8
    Re: Tips on using a Honda 2KW Briefcase to run a Mini Split AC
    Surfpath wrote: »
    ......
    Out of curiosity, (while directly hooked up to the genny) what are the consequences of fuel running out of the Honda 'briefcase' while the AC is compressing? Are there any potential adverse consequences? Just curious myself.
    8)

    Best case, you loose the prime in the fuel system and have to re-prime when you fill up the tank.

    Worst case, it's a hot day, full load, and it stops, and the cooling fan stops too, and you BBQ the alternator windings/diodes/inverter
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
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  • Surfpath
    Surfpath Solar Expert Posts: 468 ✭✭✭
    #9
    Re: Tips on using a Honda 2KW Briefcase to run a Mini Split AC

    You are right blackcherry, I got the gals/hr mixed up. Thanks for the clarification.
    Thanks also for the Genny gas running out scenarios. Sounds like the inverter AC with it's reduced load and inverter would handle that situation better than an 'ole window unit. I can advise an aux tank. Nice job guys, much appreciated.
    Outback Flexpower 1 (FM80, VFX3048E-230v, Mate, FlexNetDC) 2,730watts of "Grid-type" PV, 370 AmpHrs Trojan RE-B's, Honda 2000 watt genny, 100% off grid.
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  • PhilS
    PhilS Solar Expert Posts: 370 ✭✭✭
    #10
    Re: Tips on using a Honda 2KW Briefcase to run a Mini Split AC
    jonr wrote: »
    Block construction is typically poorly insulated. On top of that, it has high thermal mass, which means that if you want to only cool it for part of the day, there is a lot of thermal inertia to overcome.

    Also verify that the room is very well air sealed. Latent load is significant and high humidity is uncomfortable.

    I concur about the thermal mass. Our mini-split installation a few years ago is undoubtedly in the top 10 benefits I've received from this forum, maybe #1.

    Our unit (12K BTU) will keep 1/2 our home cool (78F) on 350 watts or less (about 500 sf) even when the outside temps are over 100, sometimes over 110F (well, then the interior can get up to 80F). This is in an old mobilehome, crappy insulation, metal siding, thin walls, etc.

    What the mini-split WILL NOT DO is cool the interior down once it has gotten hot. We've tried it.

    It's that "heat load"... if you can keep those bedrooms cool during the day, the mini-split will keep them cool at night. If you just turn on the mini-split in the evening and try to cool down some warm bedrooms, it won't work very well.

    I suspect you already know this but it can't be emphasized enough.

    Phil
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