atspringhill Report post Posted February 9, 2012 I have a recently installed Magum M2012 inverter / charger. When inverting it appears to be putting out 135 to 140 volts AC. Switch to generator or shore and it is 120 volts AC. Anybody have any thoughts or comments as to cause and / or correction? Lee 1999 Tradewinds Share this post Link to post Share on other sites
dickandlois Report post Posted February 9, 2012 Lee, is the voltage reading with a load on the inverter ? Have you got one of the Halogen work lights, that would put about a 500 watt load on the unit and then read the voltage level. R.M. Share this post Link to post Share on other sites
Guest BillAdams Report post Posted February 9, 2012 What makes you think (what are you seeing) that the inverter is passing voltage of this amount? Have you contacted Magnum? What did they say? Is anything else powered up when you see this or is it in an idle mode? Is this a new occurrence or something that happens from time to time? Did you have an inverter previously? If so, why did you replace it? Is this a MSW or PSW (TSW) inverter? Any additional information you can provide will help those in the know. Share this post Link to post Share on other sites
bizsmith@yahoo.com Report post Posted February 9, 2012 It is most likely that you are using a digital voltmeter that doesn't like the modified square wave of the inverter. I saw the same results, an apparent 140+ volts from the inverter but a true RMS voltmeter read right. Look at the voltage output on your coach's power panel. Some times they will show the true RMS value. The volt meters that you get at camping world that plug in to a receptacle are fine for checking shore power voltage but they will almost certainly read 140 volts from inverters and the indicated frequency is likely to be wacky. Share this post Link to post Share on other sites
atspringhill Report post Posted February 9, 2012 I will test as you suggest and see what type of reading I get. Thanks!! Lee Share this post Link to post Share on other sites
McKnight Report post Posted May 8, 2013 It is most likely that you are using a digital voltmeter that doesn't like the modified square wave of the inverter. I saw the same results, an apparent 140+ volts from the inverter but a true RMS voltmeter read right. Look at the voltage output on your coach's power panel. Some times they will show the true RMS value. The volt meters that you get at camping world that plug in to a receptacle are fine for checking shore power voltage but they will almost certainly read 140 volts from inverters and the indicated frequency is likely to be wacky. Share this post Link to post Share on other sites
