High A/C voltage -- inverter

[RRT2]

Getting ready to leave for winter. Turned on heat pump to take the chill off while we worked inside the coach. While outside, I heard a 'clack, clack, clack' sound. DH checked underneath and the squirrel cage was rubbing against the outside. OK...call dealer for appt. Bring in early, but appt is 11/25.

Now we are readying to pull out to go to dealer...start engine...pull in slides...happened to notice little volt meter showing 120 v. After DH unplugged the coach, meter jumped to 130 v. and the microwave clock was still registering. Man, whatever just happened?!

Once we got it parked at the dealer parking lot...we looked around again. Somehow the inverter had gotten turned on! Don't know when...never mind the 'how'!

Now then...our question: is 130 v normal when inverter on? What problems might we encounter from this?

Rose

[RRT2]

Getting ready to leave for winter. Turned on heat pump to take the chill off while we worked inside the coach. While outside, I heard a 'clack, clack, clack' sound. DH checked underneath and the squirrel cage was rubbing against the outside. OK...call dealer for appt. Bring in early, but appt is 11/25.

Now we are readying to pull out to go to dealer...start engine...pull in slides...happened to notice little volt meter showing 120 v. After DH unplugged the coach, meter jumped to 130 v. and the microwave clock was still registering. Man, whatever just happened?!

Once we got it parked at the dealer parking lot...we looked around again. Somehow the inverter had gotten turned on! Don't know when...never mind the 'how'!

Now then...our question: is 130 v normal when inverter on? What problems might we encounter from this?

Rose

[Clay L]

Unless they are true sinewave inverters -and most of the ones in RVs aren't - a true RMS meter is required to read the voltage accurately. It's possible (probable?) that the coach meter is not a RMS reading meter and is not telling you the truth.

I believe that the tolerance on 120 vac is +/- ten percent which would mean that 130 vac is still within the acceptable upper limit of 132 vac if it is accurate.

[FrontRangeRVer]

Clay is right on the money. If you own one of those cheap analog meters, they aren't very accurate, and they aren't true RMS meters.

SEE A RECENT POST about this.

[Route 66]

130 volts is within the 10% tolerance limits.

A True RMS voltmeter is required to read an accurate voltage from a modified sine wave inverter.

A NON True RMS voltmeter will read low.

[John_Canfield]

You would really need to use an oscilloscope to see exactly what you have coming out of the inverter. Measuring a pure sine wave, meters figure the voltage at about .7 times the peak of the wave (RMS= root mean square.) With a stepped sine or square wave, the meters aren't accurate as many others have pointed out. I forgot if you read high or low measuring a stepped sine wave with a standard voltmeter. It doesn't matter - you're fine.

(Mark - time for some Fourier analysis )

[RRT2]

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Thanks all, for your input. Guess we won't worry about anything....til it breaks!


We're getting antsy to be on our way South. 18 degrees just isn't my favorite temp!


BTW...clack clack clack on heat pump was just tightening up something. About 3' labor. But while he was 'in there', he noticed a problem with the gas furnace blower that damaged the 'wheels' . . . parts ordered. TG it's under warranty of vendor. He also found Trik-l charger not charging properly. We'll replace that ourselves.

We still plan on leaving 11/30. Or at least before Monday morning rush hour!

R