Hard Start Capacitor

teamlkc

Member
I recently purchased an NT 32BUDS that has a 13,500 A/C unit. I also purchased a Yamaha 2400 generator to run the A/C unit and thought, based on the specs, that it would work. Much to my surprise, the Yamaha doesn’t run the A/C at 10,000 ft altitude. I then read about a “hard start capacitor” and that it will help the generator to start the A/C from the initial surge at start-up. Just talked to the parts guy at my dealer and he has never heard of it.
Does anyone know anything about this “hard start capacitor” and if it is the golden bullet that it claims to be?
 

danemayer

Well-known member
If it was the 2400 inverter generator, you might want to visit this page that shows applications for each generator. It shows you need a larger generator to run a 13,500 A/C (presumably at sea level). Also, while I'm not sure how much loss there would be on gas generators, gas truck engines are said to lose about 30% of their power at 10,000 feet.
 

pegmikef

Well-known member
Yeah, there was quite a discussion about them somewhere on this forum. I have run my 15K btu ac unit at 8,000 feet with my two Hondas (about 33 amps) and they bog down pretty good starting the a/c, but they settle down as soon as it is started and it only uses about 1400 watts when it is running. Be careful modifying your ac as you might void your warranty.
 

teamlkc

Member
The good news is that once I rejetted the generator for altitude, it was able to run the A/C without a problem. Very thankful for all of the input.
 

piet10

Active Member
I bought a Honda eu2000i and wondered if it would run the A/C on the Greystone. To my surprise it worked fine! It helps that the fan comes on first for a few seconds to lower the inrush current than if both came on at the same time. I didn't try to turn on any lights, so don't know how much reserve I had. Probably not much.
 

pegmikef

Well-known member
I bought a Honda eu2000i and wondered if it would run the A/C on the Greystone. To my surprise it worked fine! It helps that the fan comes on first for a few seconds to lower the inrush current than if both came on at the same time. I didn't try to turn on any lights, so don't know how much reserve I had. Probably not much.

Wow. I haven't tried running my 15K A/C with just one. I know it wouldn't work in real hot weather like we have in TX because it routinely blows the 20 amp shore power circuit breaker. The line is dedicated, but only 20 Amps. When the temperature is cooler (80 to 90) it runs just fine on it, but once it gets warmer than that it blows it. When it cools off I am going to try running it on just one generator. I know it only draws about 1450 watts after it is running because I metered it. I don't know what the startup power is because my meter only goes to 1800 watts so it displays an error.
 

57chevyconvt

Well-known member
I have installed the additional starting capacitor as per the information on <ModMyRV.com> and it works well. I could immediately tell the difference on generator starting load requirements. I have also installed the 220 volt version on a number of house A/C condensing units to relieve some of the inrush current load that additive to the electricity consumption. Based on my experience I would say go for it, it is a easy modification.
 

evolvingpowercat

Well-known member
I replaced the OEM PTCR and 43-53 MFD Start Capacitor with the Supco SPP6E Integrated Electronic Potential Relay Style Hard Start Starting Capacitor 88-106 uF unit. My 2010 model Dometic 13,500 BTU air condition started fine at 1000 ASL in 105 degree weather with my Yamaha 2400 iSHC generator even with the OEM stuff but I thought this modification this would aid in starting when I camp at higher altitudes. I did not want to mess with changing between two sets of jets depending on what altitude I was camping at.
 

evolvingpowercat

Well-known member
FYI I found an equation for a non turbo charged engine for HP loss vs altitude:
HP loss % = Elevation (ft) * 0.003

This would predict you don't re-jet the carb, you will lose 24% of the horsepower at max RPM when running the Yamaha 2400iSHC at 8000 ft. vs. Sea Level. I have not tried mine at altitude yet to see what happens when I try to start my Dometic 13,500 AC with the Supco SPP6E replacement for the OEM start cap + PTCR, going to 8000 elevation in September so will find out then.
 
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