AC voltage and line loss

There are several things happening that you do not show with your meter readings. What you do not show is the increase in amperage, and voltage drop, when one of your AC units is first starting the compressor. This can add several more amps as well as drop the voltage 2-5 volts for a short period of time until the compressor is up and running.
Another things is that as the voltage drops, your amps used will increase for all electrical items in your coach.
If you hear your AC compressors struggling to come on, that is the best indication that the voltage is too low. This is especially true if the AC compressor cannot get started and drops back in to a fan only mode.
Volt meters are fine but they only give you an instantaneous voltage reading on a power supply that is constantly changing.

MrWizard wrote:
want to know what volatge the A/C unit is seeing

remove the covers from the circuit breaker panel
use a multimeter set on AC volts 200vac or higher (usually something like 600vac on the meter )
read from the neutral bar (the white wires buss) to the A/C breaker

probably safer if you get somebody else to do it

Thanks for the info! So there is no set info on whether the AC’s are getting the voltage coming into the rig or getting the voltage after the line drop on the internal VM?

I see you have near the same rig.. my rig is a 1997 F53 chassis too.. how do you run your AC’s together on 30 amps? Thanks!

pianotuna wrote:
A 30 amp service should only be used at 24 continuous.

If the autoformer is raising the voltage 10%, then on the input side of the autoformer the current would be much higher than 29 amps.

Anything above 107 volts is safe for the air conditioners. How are you checking the voltage inside the RV?

Thanks guys! Good to know about the amp thing, but if that’s the case how do they expect you to run both AC’s? With the Intelligec system running two AC’s at the same time is supposed to be it’s feature. Other than that the converter, fridge, and a bunch of smaller electronics are running. When AC is off completely all my toys run at 4 amps.

I have the Autoformer plugged into the shore power, the surge guard into the Autoformer and the RV into the surge guard... the surge guard was showing 29amp when both AC’s were on earlier. I have the little digital voltmeter from Hughes that came with the Autoformer plugged into an outlet over my couch.. the AC units seem to drop the internal voltmeter by about 3 or 4 volts per AC. I would consider upgrading to a 50 amp service if my Intellitec would still work for my heating and cooling but I don’t know if that’s the case... With the heat we are having here I need to run both AC’s here for a few days.. these units are now about two months old and the main unit has ran about 12 hours today for the first time ever.

want to know what volatge the A/C unit is seeing

remove the covers from the circuit breaker panel
use a multimeter set on AC volts 200vac or higher (usually something like 600vac on the meter )
read from the neutral bar (the white wires buss) to the A/C breaker

probably safer if you get somebody else to do it

A 30 amp service should only be used at 24 continuous.

If the autoformer is raising the voltage 10%, then on the input side of the autoformer the current would be much higher than 29 amps.

Anything above 107 volts is safe for the air conditioners. How are you checking the voltage inside the RV?

Can you get a reading to compare the voltmeters in the same place?
Otherwise I would trust the SG and let it run. Although 29 amps is a bit high for continuous service on 30 amps. I would have all breakers off except the mains and A/C. Put the converter back on to charge the battery when the voltage rises or in the morning.

Thanks! But I’m wondering which voltage is correct for the AC units? Are they getting the voltage the surge guard is reading or the voltage the voltmeter inside the rig is reading after line loss? Thanks!

You want you voltage to 110 or higher. Kept the sun off the power cord if you can heat drops voltage. Pick the part of motor home that has the smallest area to cool and use that AC.