I've been having some concerning issues with my RV's electrical system and I'm wondering if my inverter might be the culprit. I have a 2000 Winnebago Ultimate Advantage with four deep cycle house batteries and recently installed a Xantrex 758 inverter to replace my old Freedom 15 unit. The first time I tried using the inverter power while unplugged from shore power, something very strange happened - a hair dryer in the bathroom started running by itself and wouldn't shut off when I tried the switch. I had to unplug it, and the handle was warm. The hair dryer appears to be ruined now.
When I bought the Xantrex 758, I paid around $725 for what I thought was a good unit, but I'm now learning there's a difference between modified sine wave and pure sine wave inverters. I wasn't aware of this distinction when I made the purchase, and it turns out the 758 is a modified sine wave unit. I've since heard that modern electronics, especially things like residential refrigerators, computers, and sensitive electronic components, can be damaged by modified sine wave power.
I'm really concerned about potentially damaging my new residential refrigerator, stereo system, and computer equipment. Should I be worried about using this modified sine wave inverter with modern RV electronics? Is the hair dryer incident a sign that I need to upgrade to a pure sine wave unit, or are there other factors that could have caused this problem? I'm trying to understand if my current setup is putting my expensive electronics at risk.
Your modified sine wave Xantrex 758 likely caused the hair dryer malfunction due to waveform incompatibility with sensitive electronics. While some devices work fine with modified sine wave inverters, modern residential refrigerators, computers, and electronics require pure sine wave power to prevent damage and ensure proper operation.
Your 2000 Winnebago Ultimate Advantage 38k with the new Xantrex 2000 modified sine wave inverter is indeed putting your sensitive electronics at risk, and your hair dryer incident confirms this concern. The hair dryer starting by itself and getting hot indicates the modified sine wave was causing erratic behavior in its electronic controls. While your $725 Xantrex 2000 works for basic loads, upgrading to a pure sine wave inverter is the right call to protect your new residential refrigerator, stereo, and computer. The good news is you have several options besides selling the Xantrex 2000 and buying a $1200 pure sine unit.
Modified sine wave inverters like your Xantrex 2000 produce a stepped waveform that approximates AC power but isn't the smooth sine wave that electronics expect from grid power. This commonly causes several problems with modern RV equipment. Electronic motor controls in appliances like hair dryers can misinterpret the choppy signal, causing them to run erratically or turn on unexpectedly, exactly like you experienced.
Your new residential refrigerator is particularly vulnerable because its variable-speed compressor and electronic controls rely on clean power signals. Modified sine wave can cause the compressor to run inefficiently, overheat, or even fail prematurely. Computer power supplies and audio equipment also suffer from increased heat, buzzing, and potential component damage when fed modified sine wave power.
The issue becomes more critical as RVs incorporate more household appliances and electronics. Your 12-year gap between inverter uses means you've missed the transition period where modified sine wave went from "acceptable" to "problematic" for most RV applications.
Before making any changes, inventory all the 120V devices you plan to run on inverter power in your Winnebago. Make a list including your residential refrigerator, computers, phone chargers, LED lights, microwave, and any other electronics. This helps determine the minimum wattage you'll need from a pure sine wave inverter.
WARNING: Before working on any electrical connections, disconnect all power sources including shore power and battery disconnect switches. Use proper protective equipment including insulated tools and safety glasses.
Check your current electrical panel setup and note how the Xantrex 2000 is wired into your system. Take photos of all connections before disconnecting anything. Verify your four deep cycle house batteries are properly maintaining voltage under load - you'll want at least 12.2V per battery (60% state of charge) when disconnected and 12.0V minimum (40% state of charge) under moderate load.
Research current pure sine wave inverter options in the 1500-2000 watt range, which should handle your typical RV loads. Models like the Victron MultiPlus, Magnum MS2012, or AIMS Power pure sine units offer good value. Consider inverter/chargers that can also charge your house batteries when plugged into shore power, replacing multiple components.
Your most cost-effective option is keeping the Xantrex 2000 for emergency backup while adding a smaller pure sine wave inverter for sensitive electronics. Install a 1000-1500 watt pure sine inverter on a dedicated circuit that feeds your refrigerator, computer outlets, and entertainment center. Wire this directly to your house battery bank with appropriate fusing and leave your existing Xantrex 2000 connected to handle high-draw items like microwaves and power tools that aren't sensitive to waveform quality.
Alternatively, you can sell the 758 (expect $400-500 on the used market) and put that toward a quality pure sine inverter/charger. The Victron MultiPlus 12/2000/80 runs about $900 and provides pure sine wave output plus battery charging. The Magnum MS2012 is another excellent option around $800. Both will safely power all your electronics including that residential refrigerator.
If budget is tight, consider a smaller pure sine unit just for critical electronics. A 1000-watt pure sine inverter costs $300-400 and can handle your refrigerator, computer, and sensitive devices. Keep the 758 on a manual transfer switch for high-power, non-sensitive loads when needed.
For installation, use the same DC connections and AC wiring as your current setup, but ensure proper grounding and install appropriate DC fusing (typically 1.25x maximum current draw - verify with manufacturer specifications). If you're not comfortable with the electrical work, have an RV technician handle the installation to ensure safety and code compliance. Always torque all connections to manufacturer specifications and ensure all DC connections are properly secured with appropriate marine-grade terminals.
Contact a qualified RV electrician if you're uncomfortable working with the high-amperage DC connections required for inverter installation. The DC side can carry approximately 180-200 amps accounting for inverter efficiency losses, and improper connections can cause fires or equipment damage. Professional installation typically costs $200-400 but ensures safety and warranty coverage.
Get professional help immediately if you notice any signs of electrical problems like burning smells, warm connections, or flickering lights when using the inverter. Your hair dryer incident suggests potential wiring issues that need expert diagnosis. Also consult a pro if your house batteries aren't holding charge properly, as inverter problems can sometimes mask battery issues that need addressing first.
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