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Letsgoagain · 05-31-2009, 06:21 PM

Good evening,
Recently took a long cross country trip in the motorhome and one day while using the invertor only to power the laptop my wife said she smelled something hot. She noticed that the voltage meter I keep plugged into an outlet was pegged all the way over to 130 volts.
First of all I can't really say for sure that it normally is at a lower voltage output, say 120 volts but it seems strange that it would be at 130 volts. When I'm hooked to shore power or when I used the generator it would be in the 120 volt range.
Does anyone know what problem if any this could be indicating?

I felt the outlet to see if possibly it was getting warm (the hot smell) and it wasn't and otherwise I couldn't tell any problems. Didn't use the inverter for a few hours and then used it again the next day with no problems although the meter was maxed out again.
Appreciate any thoughts or idea's about this.
Letsgoagain

Letsgoagain · 05-31-2009, 06:38 PM

Okay, after reading some of the similar threads that pertain to this issue I think that maybe its just the volt meter not reading the modified sine wave correctly.
Seems this problem has occurred for other folks also. Think I'll do a search before posting a new thread from now on.
Letsgoagain

Cruzer · 06-01-2009, 02:09 PM

I believe you are correct. Modified sine waves don't operate regular voltmeters accurately. The 130 volt reading is about right for that scenario. For deatils on Modified Sine Waves check out http://www.rvtechlibrary.com/electrical/sinewave.htm

Route 66 · 06-01-2009, 04:48 PM

I believe reading a modified sine wave with a voltmeter that is not True-RMS capable will result in a lower voltage reading.

Usually around 104 volts or lower, whereas a True-RMS voltmeter will read correctly.

130 volts is within the 10% tolerance of the standard 120 volts, and should not normally cause a problem, although we rarely see 130 volts. Low voltage is the common problem.

Eddie Foy · 06-02-2009, 12:20 PM

If the meter is PEGGED at 130, you have no idea what the real reading is. Something above 130.

Quote:

Originally Posted by Route 66

I believe reading a modified sine wave with a voltmeter that is not True-RMS capable will result in a lower voltage reading.

Usually around 104 volts or lower, whereas a True-RMS voltmeter will read correctly.

130 volts is within the 10% tolerance of the standard 120 volts, and should not normally cause a problem, although we rarely see 130 volts. Low voltage is the common problem.

wa8yxm · 06-03-2009, 11:19 AM

I responded to this in another forum I suspect.. ROUTE 66 has it right, Usually a Peak Reading volt meter (most inexpensive meters are peak reading) will read LOW on a MSW inverter, properly on a TSW,

If you wish a short course in electricity I can explain why, but alas, Don't wish to type that much today. (Just ask)

The 130 reading (in the other forum I simply said "Don't risk it") is high.

And if you have an analog meter.. It may be reading RMS, not peak

I'd go with a True Sine replacment inverter if you can afford it.. ELse, a replacement.. If you are parked near me I might have one (But I think they are elsewhere)