dual AC on 30 amps - I think I made it work

[tim1970]

Here is what I did. Middle of day once temperatures start heating up, I switched my water heater and refrigerator over to propane. I unplugged cofee pot, curling iron, and anything else drawing electricity. I even cut off the breaker to the microwave so the clock wasn't drawing power. I also shut off the breaker that charges my batteries. I then turned on one of the AC's and let it run for about a minute. Then I turned on the other one. I have the fan set to "ON" and the thermostat for each unit all the way down, so the two units will not end up cycling at the same time. I realize this is extreme, but so far it is working. Am I harming anything by doing this? Once the sun goes down, I will turn off one of the AC's and resume everything else as normal.

[pianotuna]

From your own figures 3 x 13 = 39 amps = not able to run all 3 on 30 amps.

Cummins12V98 wrote:


I how have 3 AC's and use them ALL. If I were to be at a 30A park I would do the same.

This is what my 15k AC draws once it starts pulling power.

There was already 1A draw on L1 before I turned on the AC.

[Cummins12V98]

I did the same when on 30A with our 07.5 Mobile suites. Never an issue!!!

I how have 3 AC's and use them ALL. If I were to be at a 30A park I would do the same.

This is what my 15k AC draws once it starts pulling power.

There was already 1A draw on L1 before I turned on the AC.

[K3WE]

This is not relevant to the OP, but if you only run one AC is it generally adequate for ‘typical’ weather? (I know things vary widely- just assuming that an average camper in average weather, there’d be adequate cooling at night, and during the day you could close off the bedroom kind of deal.). Sure, if hits 100, you’re out of luck.

Just curious to hear what some other folks do.

[mowermech]

Well, golly...
Our coach has 30 amp service, with 2 air conditioners.
I frequently run both air conditioners on campground power and also on the 5500 watt generator. No problems.
The electrical system in the coach is built to handle the power distribution. I don't understand how it works, but I don't have to. It does, that's all I need to know.
But then, most of my electrical experience has been with aircraft systems; 28 VDC and 115 VAC 400 Hertz power.

[pianotuna]

Low voltage? Solve with an autoformer.

myredracer wrote:

philh wrote:
Get a soft start unit for the AC's. It really rocks!

I'm aware of the Micro-air starter. Works fine for generators that would otherwise struggle to start but isn't a cure for low CG voltage.

[CharlesinGA]

RVGeeks just did a video on running two A/C units on 30 amps, using soft start modifications to both units (and conservative use of other power users).

https://youtu.be/1mCeNRODDxc

Charles

[myredracer]

Seriously? Another double post! This needs to be fixed...

[myredracer]

philh wrote:
Get a soft start unit for the AC's. It really rocks!

I'm aware of the Micro-air starter. Works fine for generators that would otherwise struggle to start but isn't a cure for low CG voltage.

[philh]

Get a soft start unit for the AC's. It really rocks!

[myredracer]

OMG, the double posting issue is getting boring...

[myredracer]

Not recommended to run 2 ACs on 30 amps. Some will do it and claim it works just fine, but...

The momentary starting current of AC units is 50-60 amps and that will be on top of an already running AC unit and any other loads. The 80 or so amps can really drag down the voltage and an AC can struggle to start. It causes the motor windings to overheat and will cause damage. You may find you can get 2 ACs to start but the damage is cumulative and you can have an AC unit prematurely fail one day for no apparent reason. AC units are not cheap to replace...

Running AC units on chronically low voltage (at full load) is also not good when it gets down towards 105 volts. Yes, the current draw does go up somewhat too at lower voltage, although I've never been able to find data on RV units. A compressor load remains the same but as voltage goes down, a motor will generate less power and will work harder to keep the compressor going and draw more current. Again, the excessive current will cause damage to AC motors.

It's always a good idea to monitor your voltage in a CG. Newer CGs usually have decent voltage depending on where you are on a run of pedestals and if everyone else isn't running AC units. Older CGs can have high voltage drops and some sites can have long individual runs of smaller gauge wire to them which can worsen voltage drop.

A few folks have connected a 2nd AC to the 20 amp receptacle in a pedestal. But that can also be a voltage drop problem because the electrical code doesn't require wiring to pedestals to be sized for a 30 & 20 amp recept. to be running together at the same time.

If you still decide to run 2 AC units on 30 amps, I'd at least plug into a 50 amp pedestal using an adapter, *if* you can find a 50 amp pedestal (often hard to find one).

[wnjj]

twodownzero wrote:

valhalla360 wrote:

time2roll wrote:
Check your plug at the pedestal for heat.

Probably worth taking a look at the back of the breaker panel and all along the cord.

30amp is only rated for 25amp continuous, so you are really pushing the limits. If everything is in perfect condition and the voltage in the park is good, it can work.

Voltage can play a role here. If you are in a park with high voltage (but within nominal specs), it can work but if voltage drops, it will become a problem. Watts = Volts * Amps...so to maintain the same power (watts), if the voltage drops the amps will go up. If you are lucky, the breaker trips.

Never heard of Ohm's law I take it?

Ohms law has nothing to do with inductive motor loads. The current goes UP when the voltage goes down which is why windings can melt when motors aren’t fed the proper voltage.

[RoyB]

I solved my coffee pot problem of always being 'ON' keeping the coffee hot.. I went with the CUISINART BRAND Grind and Brew Coffee maker. It is only 'ON' for the five minutes or so for grinding the coffee beans and making the coffee then it pours up into a thermos carafe. This keeps my coffee hot all day... Then it shuts completely OFF... We also bring along our favorite taste bottled water just for making coffee. This insures the same good coffee taste every time... I also have a MR COFFEE grinder to grind up the beans if necessary. My truck has a low wattage PSW Power Inverter in it perfect for running the Mr Coffee grinder when needed... This way I can use my ole standby COLEMAN stove top perc to make somewhat the same taste of coffee when off grid running off my batteries... I usually however just plug the Cuisinart Grind and Brew into my 2KW generator for five minutes... That works too...


Google image

Gotta have my coffee first then I can do everything else when camping hehe

Roy's image

This all fits in great in our tent camping as well...

Roy Ken

[twodownzero]

valhalla360 wrote:

time2roll wrote:
Check your plug at the pedestal for heat.

Probably worth taking a look at the back of the breaker panel and all along the cord.

30amp is only rated for 25amp continuous, so you are really pushing the limits. If everything is in perfect condition and the voltage in the park is good, it can work.

Voltage can play a role here. If you are in a park with high voltage (but within nominal specs), it can work but if voltage drops, it will become a problem. Watts = Volts * Amps...so to maintain the same power (watts), if the voltage drops the amps will go up. If you are lucky, the breaker trips.

Never heard of Ohm's law I take it?

[dodge_guy]

You can be assured the voltage is too low for safe operation.