generator and ac on the playa

[paula]

my generator powered my ac in my driveway. but when i got to playa. it didn't make enough juice. any of you super smartie pants can 'splan it to me?

[jkisha]

my generator powered my ac in my driveway. but when i got to playa. it didn't make enough juice. any of you super smartie pants can 'splan it to me?

Yes. Many years ago, I discovered the same thing and posted about it here.

Altitude and Temperature
Altitude and temperature can have adverse effects on generator output. Let’s begin by looking at the effects of altitude. Gasoline powered gensets will decrease by 3.5% in power for each 1,000 feet of elevation above sea level.

Example: A 6 KW generator in Denver, CO
5,000 ft. elevation
3.5 x 5 =17.5% decrease
Maximum output is now 4,950 watts.

High temperatures can also decrease the efficiency of your generator by 1% for each 10° above 60° Fahrenheit.

Example: A 6 KW generator in Phoenix, AZ
It’s Labor Day weekend; the temperature is 120°
120° - 60° = 6 x 1 = 6% decrease
Maximum output is now 5,640 watts.

Now let’s see what happens when you combine high altitude and high temperature.

Example: 6 KW Generator in Denver, Colorado
Elevation: 5,000 ft. elevation
Temperature: 100° Fahrenheit.
Altitude: 3.5% x 5 =17.5% decrease
100° - 60° = 4 x 1 = 4% decrease
Total decrease = 21.5%
Maximum output is 4,710 watts.

[Savannah]

Awesome, JKisha, thank you. I'm glad to know this now, even though I don't even own a gennie!

[motskyroonmatick]

Sometimes the load on the generator is more than just the AC at the time you want to start the AC. Lets say it has been 15 hours since you last ran the generator hooked up to the trailer. In that time you used the bathroom fan, water pump and house lights plus that gizmo that you hooked up to the house battery that makes your camp look super cool. So in desperate need of AC you dive outside start the generator and hit the AC switch. BOOM! overload light flashes or generator dies. The trouble could be your trailer battery charger is trying to charge the hell out of your house batteries to get them up to par and you are simultaneously trying to start the AC and the generator (my generator) just can't do it. I was able to get my AC started by allowing my generator to warm up by putting a light load on it and waiting 5 min between start attempts on the AC. Sometimes running the generator in non eco mode and then plugging the trailer in to it worked to start the AC. Once the AC was started I switched on the eco mode and it just chugged along nicely.

What was the generator and what was the AC unit?

[Eric]

Even with our RV generator we couldn't turn the AC right on. We'd turn on the genny & then run the fan for a while. We'd only put on the AC when the fan wasn't cutting it. The few times we tried to go straight to AC we blew a breaker.

[paula]

Wow. Burners really are smart. That whole altitude/temperature thing was what I kind of suspected. I also thought maybe the dust made the gennie not pull in enough oxygen to get a hot enough burn going to turn gas into electricity.
thanks so much for the info....but i don't have a math equation for it. Maybe 2013 I need to spend more time at Math Camp...love U!

[dragonpilot]

I'll add something else slightly OT...

check the oil level on your gen. Ours was an RV mounted Onan...it failed to start for the morning coffee pot...we checked everything...fuses, breakers, inverter panel...finally just happened to look at the dip stick to find it dry. First time in 8 years...apparently there's an automatic safety cutoff when the oil level drops too low. Not sure if portable gens are so equipped.

Added a quart of Onan oil that a good Sam gave us...she fired right up...and we had coffee and no one got hurt.

[FIGJAM]

The low oil cut off is on most gennys now.

[jkisha]

How many people actually bother to change the oil per the mfg specs? I know we don't, just keep topping it off and then changing it when we get home. Just wondering, as we should probably have changed the oil 4 times in two weeks based on the hours we were running it.

[ygmir]

also remember it takes roughly twice the wattage, to start an electric motor, as it does to run it.......so, if your motor pulls 8 amps running, it'll take around 16 at initial startup. only for a few seconds, but, that can blow things.

[unjonharley]

The low oil cut off is on most gennys now.

Don't make the mistake of telling a newbe about the low oil thing , like I did.. He got it started, set it next my camp and left for the day.. Bout two hours of that shit and grandfather put the spark plug in his pocket..

[dragonpilot]

I'm sorry UJ...That's prolly my fault...I always advise gen users to place them away from their camp and next to the neighbors'...I mean, we're all Burners and love each other and all kumbayaa, right?

[Fiver]

Living at 7,500' in Utah, I was happy to get a little extra juice out of my Honda eu3000is down low on the Playa. Nice to get down to the lower altitudes once in awhile, it's amazing how you don't sunburn as easy and you feel like you could run for miles without getting out of breath.