AC Question - Boost capacitor for window unit run by small generator

Fish HaidFish Haid Posts: 7,885 Admiral

I recently changed the AC on my camper from a 5,000 BTU to 6,000 BTU.  The old one ran fine powered by my Honda 2000 generator, even on ECO setting.  The new one won't start the compressor with generator on ECO setting.  It tries, then something inside the AC senses low voltage and keeps compressor from even trying to turn on until unit is turned off and back on.

It will run fine with generator on Normal (ECO off).  I can switch to ECO after compressor comes on, and it will keep running, but after next cycle it won't restart.

Will one of these "booster capacitors" fix this?  Any way to wire that to the power cord so I don't have to remove AC from wall to install it?  Not a typical installation, sort of permanent.

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Replies

  • mindyabinessmindyabiness Posts: 3,586 Captain
    Are you using a 3-12 extension cord?
    Arguing with idiots is like playing chess with a pigeon... No matter how good you are, the bird is going to crap on the board and strut around like it won anyway. nj
  • Fish HaidFish Haid Posts: 7,885 Admiral
    Are you using a 3-12 extension cord?

    Maybe.  I can check and try.
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  • mindyabinessmindyabiness Posts: 3,586 Captain
    edited June 8 #4
    It happens with my portable compressor on 120vac house current. If I don't have a 3-12 cord, it short cycles...and that's bad for everything.
    If you have a refrigerator in your camper, it may do the same thing as your air conditioner except you won't know it until your frig quits.
    The cord should be as short as possible. I made one from 3-10 SOOW cord for my camper.
    Arguing with idiots is like playing chess with a pigeon... No matter how good you are, the bird is going to crap on the board and strut around like it won anyway. nj
  • ScoutboatScoutboat Posts: 1,722 Captain
    Fish Haid said:

    I recently changed the AC on my camper from a 5,000 BTU to 6,000 BTU.  The old one ran fine powered by my Honda 2000 generator, even on ECO setting.  The new one won't start the compressor with generator on ECO setting.  It tries, then something inside the AC senses low voltage and keeps compressor from even trying to turn on until unit is turned off and back on.

    It will run fine with generator on Normal (ECO off).  I can switch to ECO after compressor comes on, and it will keep running, but after next cycle it won't restart.

    Will one of these "booster capacitors" fix this?  Any way to wire that to the power cord so I don't have to remove AC from wall to install it?  Not a typical installation, sort of permanent.

    You probably need a higher capacity generator.
  • TarponatorTarponator Under a BridgePosts: 9,873 Admiral
    Have you put a meter or scope on the voltage and watched it during the cycle? 

    Presuming you've correctly diagnosed the problem, I'd be looking into a battery, but an array of capacitors should also work.  They will both buffer the current draw from generator and provide some stability to the voltage -- however sizing them might be a bit of a challenge.

    Hopefully someone that does this for a living will pipe up....
  • Gary SGary S Posts: 674 Officer
    Not sure why a battery would do anything, A hard start kit might help if it doesn't already have one. Yes it would have to come apart to be wired in, It connects to compressor terminals. The problem is the compressor draws a lot of current on start up and the 2000 needs a head start to get it started. You really need to take the generator off eco even though it will run without it once the compressor is running. If the compressor cycles at nigh it won't be able to restart if it's in eco. Running on low voltage is very hard on the compressor. If running off eco isn't the answer you want upgrading to a Honda 3000 would solve you problems.
  • TarponatorTarponator Under a BridgePosts: 9,873 Admiral
    edited June 9 #9
    Gary S said:
    Not sure why a battery would do anything, A hard start kit might help if it doesn't already have one. Yes it would have to come apart to be wired in, It connects to compressor terminals. The problem is the compressor draws a lot of current on start up and the 2000 needs a head start to get it started. You really need to take the generator off eco even though it will run without it once the compressor is running. If the compressor cycles at nigh it won't be able to restart if it's in eco. Running on low voltage is very hard on the compressor. If running off eco isn't the answer you want upgrading to a Honda 3000 would solve you problems.
    A battery would buffer the current draw by the compressor, which is leading to the drop in voltage and the compressor not starting.   Said a bit differently, by providing additional current, the battery (or cap bank) would allow the generator's voltage to not drop and the AC to function normally.  

    That said, I agree, getting a bigger generator would solve the problem.  It's also much more expensive than a battery and/or a bank of capacitors -- and why I suspect Fish Haid suggested this in his post.
  • Gary SGary S Posts: 674 Officer
    Could you show me a picture of a battery you would use or maybe a link where I could read up on how to do this? I was in the trade for 38 years and never heard of a battery being used to boast voltage. I have been retired now for 6 years and something new might have come up.
  • Fish HaidFish Haid Posts: 7,885 Admiral

    My Honda 2000 is a bit old.  Not sure if they "lose power" when they age.  I would not mind getting a new Honda 2200, if the extra 200 watts would make a difference.

    The 2000 easily ran the 5000 btu unit on ECO mode.  Didn't even stumble when compressor kicked on.  The microwave actually drew more current.  I could even run the microwave with the AC running, but just barely (on ECO mode).

    The new AC (6000) has digital controls.  Old one had analog (thermostat dial).  I wonder it the low voltage safety switch is built into the digital circuit?  Maybe I should get a new 6000 AC with analog control?

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  • mindyabinessmindyabiness Posts: 3,586 Captain
    edited June 10 #12

    This 6000 BTU unit needs 4.9 amps. The start up current is probably a little lees than 2x that.
    9 amps.....
    Your 2000 watt generator is providing you with16 amps at 120 vac.   in a perfect world.When the amp draw goes up the engine rpm must increase. There is usually a lag when this happens and this lag becomes greater on an older unit. Its a gas engine and things wear, wires get old as do spark plugs, air cleaners,,,,you get the idea
    It should work if everything is running correctly. So something is not working right and I suspect it's the generator.
    If you have a volt meter your could see the voltage provided. If you a really nice volt meter you check the sine wave which should be 60 hz. If the frequency is off just a little, that's a problem.
    If the volts are low the amp draw goes up.
    Are you maintaining the generator correctly, is it running smooth. easy to start?

    What about the extension cord?

    Arguing with idiots is like playing chess with a pigeon... No matter how good you are, the bird is going to crap on the board and strut around like it won anyway. nj
  • Fish HaidFish Haid Posts: 7,885 Admiral

    Generator is fine and maintained.  Like I said, generator ran the old 5000 AC fine.  It runs this one too, just won't start it.  Normally, if generator is overloaded, the generator will just quit.  This new (6000) AC has electronic controls.  Generator doesn't quit, nor does AC fan - it just triggers AC not to try and turn on compressor anymore (a red light flashes).  So, I think my problem is just the AC "brain" is too sensitive.  I just ordered another 6,000 AC with non-digital controls (2 knobs like the old days).  Of course, maybe low voltage was why the 5000 failed after 2 years.  Or- it is just modern crap - only cost $100 brand new.

    New non-digital 6000 AC was $169.  Same as I paid for the digital 6000.  I will try the new non-digital with generator before I remove the other one.  Never bad to have an extra around - I can sell the unneeded one (which will still be new) for $250 after the next hurricane!

    I will report back after I test it.

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  • AC ManAC Man Posts: 3,658 Captain
    edited June 13 #14
    If the new mechanical controls machine start you just got lucky. The compressor is kicking off on the compressor thermal overload, not related to electronic controls per se. That said, you will be far better off with mechanical controls. They are getting hard to find.and a million times more reliable 

    #1 If you have a power failure or a glitch in the compressor starting with electronic controls it will cycle off and will not reset automatically and try to start again. You have to reset it. This is bad at remote unmanned sites and not an option.

    #2 We haven't serviced window shakers in many moons, but I am almost sure they still have a recip compressor VS Scroll as  in all central A/C these days. Recip has much more starting torque required so you still may need to add a start kit.At least it wont shut off like electronic controls and you are dead in the water. The mechanical control machine will keep trying to restart the compressor till the A/C or generator gives out.

    #3 If the compressor does start and is running, if it cycles off or you turn it off, you have to wait at least 5 minutes to restart the A/C to let the pressures equalize. 

    #4 You are pushing the limits of a 2000 generator on ECO to start the compressor. Most of the time the generator cant catch up  with the start load of the compressor.

    #4 When I had a 5000 generator on my house back in 2004 with a 1.5 ton recip compressor on the bedroom side it would not start it till I installed a start kit.

    #5 I have never in my life had a reason to add a start kit to a window shaker, but if you do, add the one designed for the compressor..Guarantee it will work.

    FWIW  My camper has a 12k roof top A/C and a 3k Honda generator will start the unit in ECO mode no problem. I found that my minimal camper which is nothing more than a car hauler with a few sleeping arrangements at the race track required the Honda 3000 whisper quiet generator. Works great on the house too when the power goes out.Might want to move up.
  • Fish HaidFish Haid Posts: 7,885 Admiral

    Don't have room for the 3000 generator.  I was wondering if the new 2200 would be strong enough.

    The old 5000 btu cooled good enough at night, but just need more in bright sun on 95 degree day.  The new 6000 was definitely cooler.

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  • mindyabinessmindyabiness Posts: 3,586 Captain
    Your not answering the questions regarding the extension cord.
    That could very well be the problem
    How long is the cord and what is the wire size?
    Arguing with idiots is like playing chess with a pigeon... No matter how good you are, the bird is going to crap on the board and strut around like it won anyway. nj
  • AC ManAC Man Posts: 3,658 Captain
    Your not answering the questions regarding the extension cord.
    That could very well be the problem
    How long is the cord and what is the wire size?
    I missed that and yes it could be a issue. Heavy short cord is a must.
  • Gary SGary S Posts: 674 Officer
    I still want to see this battery that will solve the problem.
  • mindyabinessmindyabiness Posts: 3,586 Captain
    Gary S said:
    I still want to see this battery that will solve the problem.
    Yea.....me too. But that's not going to happen.
    I was looking forward to learning how you connect DC cell to AC current without a charging circuit.
    And what kind of battery?
    Arguing with idiots is like playing chess with a pigeon... No matter how good you are, the bird is going to crap on the board and strut around like it won anyway. nj

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