A/C on 30 amps.

[JorgeS]

Originally Posted by Mtn. Lion

It sounds like BTU to watt calculators aren't very accurate. Or I did it wrong, or both

Maybe wrong approach...
BTUs are how much heat (energy) the AC removes in a certain amount of time. Because the AC is just moving that energy from one place to another, it can do that using a smaller amount of energy.
It's quite possible for an AC to use 1.5kW of electricity to move 15kW of heat.
The EER you see on an AC is a measure of the ratio between heat removed and energy used to move that heat.


I have a question: on our first long trip, we spent a week in Kerrville TX June 2018. In order to camp near other members of our motorcycle club, we chose a spot with 30A service.
Because we didn't know any better, we ran both ACs during the days, with outside temperatures going into the mid/high 90s.
I do not remember tripping the breaker... The coach was sure nice and comfy every day when we returned. :-)

How do we get away with this?

[twinboat]

A 3600 watt generator will run 1 AC and the microwave, add in the 1900 watts and the second AC is no problem.

That's why they install 5500 watt generators.

[KanzKran]

Originally Posted by JorgeS

I have a question: on our first long trip, we spent a week in Kerrville TX June 2018. In order to camp near other members of our motorcycle club, we chose a spot with 30A service.
Because we didn't know any better, we ran both ACs during the days, with outside temperatures going into the mid/high 90s.
I do not remember tripping the breaker... The coach was sure nice and comfy every day when we returned. :-)

How do we get away with this?

By the skin of your teeth, I would say.

Some of the Dometics show FLA as low as 15A for 13,500 Btu/hr (a little less for 11k units), but that's not necessarily what they will actually draw. I don't know about A/C units specifically, but many motorized loads actually draw a little less than the nameplate value, and I suspect that's not an accident.

Just checked Coleman - the Mach 10 shows 11.6A cooling for 11,500 Btu/hr and 14.4A for the 15kBtu/hr models, so those could be well under 30A for the two.

[sibe]

in my experience, RV Park or home current can start AC and run a bit more than most Gennys of an equal circuit for ex 30A..

My old 15K AC when running on low fan with ful cold.. chugs around 13 amps.. 1480watts.. when the compresser cycles i see it spike 18-20A,, I just tested this today.. Only becasue by garage power is "weak" I have a temporary 14/3 wire run 250ft to feed my panel// LONG story it is a TEMP..
Any way I can run that AC on a 20amp breaker.. I also watched my amprobe meters and fluke .. when AC copm cycles.. I get 21A at panel and volt drop to 108 for a sec... I did dont run it too long,, 14/3 did not even get warm but on idle I have 120V,, with AC on running 114-115.. that long run kills it..

ANY WAY it works AC,, NOW I get a Ryobi 2200.. Running full.. 1800watt run.. If I start AC on fan then drop in temp.. she holds , BUT if I turn temp comtrol, kill comp and force a restart,, the Ryobi fails..

I did the same with my Honda 3000,, It works but only with eco OFF..
MY knock off 3500 Greenpower.. It will run AC from ECO but once if i keep forcing the compressor restarts it rather be off ECO,, it fails occasionally..
I also fired the microwave it is a 1200 watt... 1 minute is ran but 3500 was screaming hard..

Itried it with honda she tripped..

Genny power out put is a tad different from Service power...

OH by the way the ONAN4000 onboard, will handle the AC on high fan,, TV on , Fridge on and a burst from microwave,, it bunkered down, shook then climbed RPM.. I looked and we had 27.3 AMP,, 113V 3440RPM... I may be able to tweek carb and govener to get RPM up a bit..but I was pushing it ..

Just some useless info I know..

[dkoldman]

Originally Posted by JorgeS

Maybe wrong approach...
BTUs are how much heat (energy) the AC removes in a certain amount of time. Because the AC is just moving that energy from one place to another, it can do that using a smaller amount of energy.
It's quite possible for an AC to use 1.5kW of electricity to move 15kW of heat.
The EER you see on an AC is a measure of the ratio between heat removed and energy used to move that heat.


I have a question: on our first long trip, we spent a week in Kerrville TX June 2018. In order to camp near other members of our motorcycle club, we chose a spot with 30A service.
Because we didn't know any better, we ran both ACs during the days, with outside temperatures going into the mid/high 90s.
I do not remember tripping the breaker... The coach was sure nice and comfy every day when we returned. :-)

How do we get away with this?

What size are both units. It is 1990, are you sure it does not have soft start? or possibly some energy management system? If none of the above, next time you get a chance see if both compressors are actually running at the same time? If they are you have highly efficient startup compressors. I have 2 13.5btus, my power management system knows if I only have 20 or 30amp services and will control the 2nd AC from trying to start, unless I insist to do some damage

[Old Scout]

Wont debate the numbers but think we can/should agree that running 2 AC's will push the "typical" 30 amp service to its limits.....the problem is that for a lot of campgrounds, the 30 amp pedestal plugs have been used and abused over the years [probably from RVs using two AC's], so poor contact at the plug could raise amps and reduce volts....regardless, you always need to monitor volts when on 30 amp shore power, the breaker won't always protect you from yourself.....

[JorgeS]

Thanks a lot, Oldscout! Make me feel guilty :-(
I'll have to check how much current the ACs are actually pulling.
It's probably due to both compressors not during at the same time-



Dkoldman, I think the only per management they knew back then was the accelerator.

I've read about Soft Start, but I'm pretty sure I don't have one.


I've got decent meters, including peak- hold, so I should be able to capture the inrush for the compressors.
Live and learn. Thankfully, I got away with it with no here to the ACs.


Thanks for the comments.

[dkoldman]

Originally Posted by JorgeS

Dkoldman, I think the only per management they knew back then was the accelerator. I've read about Soft Start, but I'm pretty sure I don't have one.
.

Well if your coach was made before they started using round wheels.... oh well I might be beating a dead horse ...

[SailorSam]

Originally Posted by JorgeS

I've got decent meters, including peak- hold, so I should be able to capture the inrush for the compressors.
Live and learn. Thankfully, I got away with it with no here to the ACs.


Thanks for the comments.

Unless you have custom designed a meter, you probably won't catch the initial inrush. Mateo, the engineer who has a couple of u-tube on the EZ-Start made one. The initial inrush value is only present for a nano-second or three... If you look at the motor on your compressor, it may have a LRA rating - that is the inital inrush amps.

[JorgeS]

Round wheels... When?
Really, our Beast has none of the newer tech stuff like power management. On the 120V side, it's pretty much circuit breakers and wires and nothing else... simple old school stuff.


I'll have to look up those videos.

Thank you.

[glennwest]

1000 watt generator will run mine. But it is a mini split

[StepandWolf]

Originally Posted by profdan

Someone mentioned that no one boondocking will complain about a generator. Maybe not, but I have done some grumbling about other boondockers who run loud generators day and night.

Grumble.

That makes me want to bring up the comparison to "job site" type gens that are flat out loud. In comparison, the inverter generators run a lot quieter and can throttle down when use drops, like when AC is off.

They are all "too" loud when we want total peace and quiet.

[Phil G.]

...

[Phil G.]

Originally Posted by Old Scout

Wont debate the numbers but think we can/should agree that running 2 AC's will push the "typical" 30 amp service to its limits.....the problem is that for a lot of campgrounds, the 30 amp pedestal plugs have been used and abused over the years [probably from RVs using two AC's], so poor contact at the plug could raise amps and reduce volts....regardless, you always need to monitor volts when on 30 amp shore power, the breaker won't always protect you from yourself.....

I've monitored some discussions in forums where 30 amp RV owners use the 50 amp pedestal connector and an adapter to get "better"- or at least more "reliable" - 30 amp power for their RVs.

This seems to make sense as maybe a way to get full(er) power on hookups in a 30 amp rig.