Run Both 13.M A/C Units on 30 Amps?

[69RoadRunner]

Can you run both 13.5M A/C units on a hot day with 30 amp service? I found a campground that's first come/first served, and the 50 amp sites go quickly.

It gets hot there (100 degrees 2 years ago with 3000% humidity). It's a very convenient location, though.

If I can't keep the coach cool on 30 amps, I'll stay at a nearby KOA where I can reserve a 50 amp spot.

[69RoadRunner]

Can you run both 13.5M A/C units on a hot day with 30 amp service? I found a campground that's first come/first served, and the 50 amp sites go quickly.

It gets hot there (100 degrees 2 years ago with 3000% humidity). It's a very convenient location, though.

If I can't keep the coach cool on 30 amps, I'll stay at a nearby KOA where I can reserve a 50 amp spot.

[Norm Payne]

If it is a "good" 30 amp you can run both air conditioners. I have done it often, but i turn off the electric to the water heater, put the refrigerator on LP and don't use the microwave.

[Ecker]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by 69RoadRunner:
Can you run both 13.5M A/C units on a hot day with 30 amp service? I found a campground that's first come/first served, and the 50 amp sites go quickly.

It gets hot there (100 degrees 2 years ago with 3000% humidity). It's a very convenient location, though.

If I can't keep the coach cool on 30 amps, I'll stay at a nearby KOA where I can reserve a 50 amp spot. </div></BLOCKQUOTE>

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Assuming these are Carriers, but others will be similar, these units require 13.4 amps at full load. Thus if both were working you would be 26.8. However, that leaves no room for one starting and drawing more current or for other appliances like refrigerator,battery charger, etc. In addition, many motorhomes are wired so only one can be run on shore power. Other motorhomes do have shedding controls so it would shed off one if the total current exceeds 30 amps. Bottom line not likely you will be able to run both especially since the power draw in park will be high, voltage will drop and current will increase thus exacerbating the problem.

[Dav5942]

Exactly why you should have the EMS. It will shed and allow both ACs to run most of the time. However even without EMS(we forgot to order) we have been able to run 2 of the 3 15k BTU ACs most of the time(requires turning off the major consumption devices and for the batteries to be fully charged so the Inverter/Charger does not eat up a lot of current).

[69RoadRunner]

I REALLY wish I could get EMS, but it's not an option on the 2009 Ventana, and they won't do a special.

What happens if you run the generator while on shore power? Is it like crossing the streams in Ghostbusters?

[Ecker]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by 69RoadRunner:
I REALLY wish I could get EMS, but it's not an option on the 2009 Ventana, and they won't do a special.

What happens if you run the generator while on shore power? Is it like crossing the streams in Ghostbusters? </div></BLOCKQUOTE>
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The generator is considered the primary source - so the transfer switch will drop off the power cord after a few seconds of programmed delay and then your unit will run from the generator. Then depending on the genset option you chose you have 60+ amps of available current.

[jmon129]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by 69RoadRunner:
Can you run both 13.5M A/C units on a hot day with 30 amp service? I found a campground that's first come/first served, and the 50 amp sites go quickly.

It gets hot there (100 degrees 2 years ago with 3000% humidity). It's a very convenient location, though.

If I can't keep the coach cool on 30 amps, I'll stay at a nearby KOA where I can reserve a 50 amp spot. </div></BLOCKQUOTE>

Can be done, but should not be done. It takes 19 amps to get the compresser up and running after a few minute it will be drawing between 12.9-13.9 amps. Depends on the unit.
It is bad to run both because the compressers will try and run, sometimes they will but your putting a hard load on them. Will shorten the life span considerbly.

[69RoadRunner]

Thanks. It's better to ask stupid questions now than to do stupid things later.

[Dav5942]

[QUOTE]Originally posted by jmon129:

Can be done, but should not be done. It takes 19 amps to get the compresser up and running after a few minute it will be drawing between 12.9-13.9 amps. Depends on the unit.
It is bad to run both because the compressers will try and run, sometimes they will but your putting a hard load on them. Will shorten the life span considerbly.[/QUOTE
]

Maybe true in theory, but highly unlikely to be noticed by the average RVer in actual use of an average use RV AC(IMHO based on real world experience). Worst case maybe a start cap after 3 years. You will most likely(if you do a lot of camping) have 30 amp service quite often-use it and enjoy!

[Norm Payne]

The 13.5M air conditioners in your 2009 Ventana will draw between 11 and 12 amps each, depending on temperature and other factors. The fans come on first and after they are up to speed the compressors will kick in one at a time. They have soft start or capacitor assisted starts so they won't draw a heavy current like the old units.

You can run both air conditioners on 30-amp without doing any harm to them.

Now, this is not necessarily true on older air conditioners or even 15M units. But your modern 13.5M units will do just fine.

[RVDude]

Theory and practice can be different. Simply put, you really do NOT want to run your units at less than 105v. That is your deciding factor (aside from exceeding 30amp total). Check your A/C manual for min operating voltage, it may be higher.

You said HOT (100 degree) operating conditions. That is going to tax the CG power heavily. That means you will likely be getting low voltage. If the CG has mostly 30amp service, it sounds a little dated thus exacerbating the low voltage possibility. And of course, the lower the voltage the higher the amp draw thus making everything even worse.

So, running 2 units though while quite possible given a really good 30amp supply as mentioned above (i.e. holding 120v), it sounds like you are in less than ideal conditions and only one unit will (should) be operated.

Keep your voltmeter handy. If you are running your Progressive electrical protector, be prepared for frequent shutdowns.

[Dav5942]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by RVDude:
Theory and practice can be different. Simply put, you really do NOT want to run your units at less than 105v. That is your deciding factor (aside from exceeding 30amp total). Check your A/C manual for min operating voltage, it may be higher.

You said HOT (100 degree) operating conditions. That is going to tax the CG power heavily. That means you will likely be getting low voltage. If the CG has mostly 30amp service, it sounds a little dated thus exacerbating the low voltage possibility. And of course, the lower the voltage the higher the amp draw thus making everything even worse.

So, running 2 units though while quite possible given a really good 30amp supply as mentioned above (i.e. holding 120v), it sounds like you are in less than ideal conditions and only one unit will (should) be operated.

Keep your voltmeter handy. If you are running your Progressive electrical protector, be prepared for frequent shutdowns. </div></BLOCKQUOTE>

Most of the newer ACs will cutoff below 105v and have seen very few 30 or even 50 amp services that maintain 120volts(most are in the neighborhood of 115 or less under load). Would not be concerned as even without a Progressive voltage/surge protector in over 30 years of camping/boating we have never lost anything electrical because of low or high voltage, now lightning and hot neutral leads thats another story(just get out there and enjoy).

[Spikester]

One thing no-one has mentioned is that you will get some air-flow to the rear of your coach with just the front AC unit running and visa-versa. With 30 Amps of SP power once you have cooled the MH off you can shift to one AC with the fan mode in high or low which will probably keep your MH cooled down. Remember you have common supply and return headers, 2 AC's suppling one common discharge header running the length of the entire unit.
I have ran both of my AC's 30Amps but you cannot run much else, shifted to one AC as mentioned above, kept MH at 71 degrees with outside temp of 92 degrees, but MH is 34' not 39'.
A previous post mentioned making sure your batteries are fully charged to limit your inverter draws, you should be able to manually turn off the battery charger on your inverter control panel so this will not be an issue, I can on my Ventana. Your inverter should be turned off also.
Once you become familiar with your electrical system and HVAC you will be able to keep your coach at the temperature you desire regardless of the amount of power available in the campground.

Spike