Banging my head on window AC mods to reduce start up amp spike!

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TucsonAZ
TucsonAZ Solar Expert Posts: 139 ✭✭
in Off Grid Solar & Battery Systems #1
So I've been messing with a 5,000 btu window AC unit in preparation for my next build.  So far I added a SPP5 hard start cap to it (plan on adding one to my chest freezer to fridge conversion as well).  Here are the results of that:

Amps drawn on startup before 17.9
Amps drawn startup after 12.6

Additionally amps drawn when manually starting the fan and waiting 5 seconds to start the compressor were 6 amps which levels off to 3-5 amps fairly quickly.

I'm very curious about running this on my 1,300 watts of solar as I'm expecting a draw of roughly 500 watts per hour. My hopes are that I'm able to get 4 hours of use on occasion to let me sleep in a little if the morning is hot.

The biggest issue I'm having would be avoiding rapid cycling and how to start the fan and have the compressor come on 10 seconds later.  Here's the best I've got:



My build is 100sqft and mobile, I will have R12 walls and R15 in the roof so I don't think I have a major concern of rapid cycling. 

Anyway, just sharing my thoughts in the event anybody else finds themselves with the same struggles. 


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  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,746 ✭✭✭✭✭✭
    edited July 2018 #2
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    I was there where you are once. I think you should read this thread I did. I have seen a 6K btu mini split. 
    http://forum.solar-electric.com/discussion/23007/mini-split-update-for-offgrid
    Good Luck
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

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  • Photowhit
    Photowhit Solar Expert Posts: 6,003 ✭✭✭✭✭
    #3
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    Not sure why you are adding start features, would it not start on your inverter?

    I've run a 5200 btu window air for 4 years on a small system, I did build the cabin to run an air conditioner, about R-20 walls R-30 floor and ceiling. It was 10x16 and fixed. The array started at 1000 watts and grew to 1600 watts allowing for more daytime use when the batteries became full. 24 volt, 4 golf cart battery bank, ran on 1800 watt pure sine inverter.

    I suspect you need to worry about other things. In the morning you won't have much solar input, you will mostly be running off your stored energy. What battery bank voltage and size? Also being mobile, you will need to worry about having optimal angle on your solar panels. Also free of obstructions, just a little shading can rob 90% of output. Also a pure sine inverter will make a difference, in energy used and life of the air conditioner.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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