The Ultimate RV Propane Monitor Comparison: Mopeka vs. Lippert vs. The Rest

It's 4 AM, the temperature is dropping below freezing, and your RV furnace clicks off. You’ve just run out of propane.

If you’re an RVer, you’ve either lived this scenario or you live in fear of it. For decades, we’ve been forced to rely on "gauges" that are little more than decorations, or the ol' "tap the tank" method, which is about as accurate as guessing. Nothing is worse than that furnace cutting out in a cold snap. That's not a 'guess,' that's an experience I've had, and it’s why a reliable monitor isn't a luxury—it's essential.

But the market is now flooded with "smart" monitors, all promising perfect accuracy. How do you choose?

This guide isn't just another "top 3" list. We are going to dive deep, based on 15+ years of industry experience, into the technology and real-world performance of smart propane monitors. We'll put the two industry leaders, Mopeka and Lippert, in a head-to-head battle, and also see how "other leading brands" like Generac stack up.

By the end, you will know exactly which monitor to buy for your specific RV setup, how to install it for maximum accuracy, and how to never run out of propane unexpectedly again.

First, a Critical Distinction: Propane Monitors vs. Propane Alarms

Before we go one step further, we have to clear this up. This is the number one point of confusion I see, and competitors often lump them together, which is confusing and, frankly, dangerous.

• Propane Level Monitor: This is your "fuel gauge." Its only job is to tell you how much propane (in liquid form) is left in your tank. It answers the question, "Am I at 30% or 80%?" It typically lives on the tank itself. The Mopeka and Lippert sensors are level monitors.
• Propane Leak Alarm/Detector: This is your "safety alarm." It's a life-saving device that sniffs the air inside your RV. If it detects the smell of propane (or Carbon Monoxide, as they're often combined), it screams at you to get out. It's usually hard-wired near your floor, since propane is heavier than air.

You absolutely need both. They are not interchangeable. This article focuses on level monitors—the ones that stop you from running out in the first place. For a deeper dive into the safety side, you can read our guide on RV propane safety.

Why Your Old Propane Gauge Is Lying to You (The 3 Tech Types)

Why are those cheap in-line gauges so useless? It all comes down to high school physics.

Propane, or LPG, exists as a liquid inside your tank because it's under pressure. As long as there is any liquid left—whether the tank is 90% full or 10% full—the pressure of the gas at the top remains relatively constant (it changes with temperature, but not with level).

Those cheap dial gauges only measure that gas pressure. The pressure only drops off a cliff when the very last bit of liquid has boiled off and you're running on the last fumes.

Here's what most suppliers won't tell you: an in-line pressure gauge is a "run-empty" indicator, not a "level" indicator. In my opinion, they are almost useless.

Thankfully, we have two modern technologies that actually work.

Technology #1: Ultrasonic Sensors (The "Smart" Way)

This is the tech used by Mopeka, Lippert, and BMPRO. The sensor mounts to the bottom of your steel tank (usually with magnets) and sends an ultrasonic pulse (a sound wave) straight up. It then measures the precise time it takes for that pulse to bounce off the surface of the liquid propane and return.

It's essentially sonar for your propane tank. The app does the math and displays the level as a percentage.

• Pros: Measures the actual liquid level, connects to your phone via Bluetooth, and offers "smart" features and integration.
• Cons: Accuracy can be +/- 5-10% and is highly dependent on a correct installation. (Don't worry, I'll show you how to do it right).

Technology #2: Weight Scales (The "Weight" Way)

This is the approach taken by brands like Flame King. It’s a digital scale that you place your entire propane tank on. You input your tank's "tare weight" (the empty weight, stamped on the handle) into an app, and the scale does the simple math: (Total Weight - Tare Weight) = Propane Weight.

• Pros: Very, very accurate. Weight is a fixed measurement.
• Cons: It can be bulky, requires you to remove the tank to place it on the scale, and the apps are often very basic. It also doesn't work for fixed, built-in ASME tanks on motorhomes.

Head-to-Head: Mopeka vs. Lippert

This is the main event. Both use ultrasonic technology, but they are aimed at two very different RVers. The choice here isn't just about the sensor; it's about the ecosystem.

Mopeka (The Industry Specialist)

Mopeka is a specialist; this is what they do. Their flagship models are the Mopeka Pro Check and PRO+ series.

• Technology: Ultrasonic, attaching magnetically to the bottom of steel tanks. For RVers with aluminum tanks, this is a critical point: you must buy their Universal Mounting Collar (a plastic ring that glues to the tank) to hold the sensor in place.
• The App: It uses the standalone "Mopeka Tank Check" app. It's functional and can monitor multiple tanks (propane, water, etc.). You can set customizable alarms, and it works well.
• Integration (The Killer Feature): This is Mopeka's trump card. It's the only sensor on the market that integrates directly with high-end RV management systems like Victron Energy (via the Cerbo GX) and RV Whisper. For tech-savvy RVers building a fully integrated smart RV, Mopeka is the professional's choice.
• Battery: A simple, user-replaceable CR2032 coin battery that, in my experience, lasts 3-5 years.

Lippert (The Ecosystem Integrator)

Lippert is the 800-pound gorilla in the RV parts world. Their sensor is just one small piece of their massive "smart RV" puzzle.

• Technology: Also ultrasonic and magnetic for steel tanks.
• The App: Here's the catch. It doesn't have its own app. The Lippert Propane Tank Sensor is designed to feed data only into the Lippert OneControl app. This is the same app that likely already runs your RV's slides, leveling jacks, awnings, and lights.
• Integration: If your new travel trailer or fifth wheel came with a OneControl touchscreen, this is the obvious, seamless choice. The data will pop up right on your main control screen. If you don't have a OneControl-equipped RV, this product is not for you.
• Battery: Also a user-replaceable CR2032.

Here's the data in a clean comparison:

Feature	Mopeka Pro Check	Lippert OneControl Sensor
Technology	Ultrasonic	Ultrasonic
App	Mopeka Tank Check (Standalone)	Lippert OneControl (Integrated)
Integration	Excellent (Victron, RV Whisper)	Excellent (OneControl only)
Steel Tank	Yes (Magnetic)	Yes (Magnetic)
Aluminum Tank	Yes (with optional collar)	No (Not officially supported)
Battery	CR2032 (Replaceable)	CR2032 (Replaceable)
Best For...	Tech-savvy RVers, Victron users, or anyone needing a standalone solution.	RVers who already have the Lippert OneControl system.

The "Other Leading Brands" Worth Your Time

While Mopeka and Lippert dominate, a couple of others fill important niches.

Generac LTE Propane Monitor

• The "Cellular" Option: This one is unique. It doesn't use Bluetooth, which has a 50-100ft range. It uses LTE (cellular) to report your tank level to an app.
• Pros: You can check your propane level from anywhere in the world. This is fantastic for people who leave their RV in storage (with the heat on) or rent it out.
• Cons (Trustworthiness): Let's be transparent about the real-world limitation. It requires an annual subscription fee (around $50/year last I checked) for that cellular service. Most competitors have no fees.

Flame King Smart Scale

• The "Weight" Option: As we discussed, this is a digital scale.
• Pros: It's the most accurate method, period.
• Cons: The app is very basic. More importantly, it only works for removable DOT tanks (like on a travel trailer) and you must have room in your tank tray for the scale to sit under the tank, which can be a tight fit. It's a non-starter for fixed ASME tanks on motorhomes.

How to Install Your Monitor for Actual Accuracy (My First-Hand Guide)

I've seen dozens of 1-star reviews from people who just slapped the sensor on a dirty, rusty tank, complained it didn't work, and returned it. Don't be that person.

In my experience, 90% of accuracy problems are installation problems. An ultrasonic sensor is a sensitive instrument. Follow these steps, and it will work. For a full walkthrough, check our guide to installing a wireless propane gauge.

Step 1: Get Clearance (The Spacer Problem)

Go look at your RV's propane tray. I'll bet your tanks sit flat on the metal bottom, right? The sensor needs at least 1/2-inch of space underneath it, both to avoid being crushed and to properly transmit its Bluetooth signal.

• The Solution: You MUST use spacers or "tank feet." Mopeka sells a plastic ring called the "Tank Halo" that works perfectly. You can also find 3D-printed or rubber feet online. Do not skip this.

Step 2: Prep the Surface

The sensor has to go on the exact center of the tank's bottom. It can't be on a weld seam or on the outer rim.

• The Solution: Clean that center spot. If it's caked in mud or has 10 layers of old paint and rust, take a bit of sandpaper and lightly scuff it down to clean metal.

Step 3: The Secret Weapon (Dielectric Grease)

This is the #1 tip I can give you, and it's what separates a "guess" from a "reading." An ultrasonic sensor sends sound. It needs a perfect, gap-free medium to travel from the sensor's face to the tank's metal. Air is its enemy.

• The Solution: Get a tube of dielectric grease (any auto parts store has it). Apply a generous "glob" of it to the face of the sensor before you stick it to the tank. This fills all the microscopic air gaps and ensures a crystal-clear signal.

Step 4: Sync and Settle

Sync the sensor to your app before you put the tank back in the tray. And one last thing: right after a refill, the liquid propane is sloshing around and turbulent. Your first reading might be erratic. Just give the sensor 10-15 minutes to "settle" and get a stable, accurate reading.

My Final Verdict: The Best RV Propane Monitor for You

So, what's the bottom line? Here’s my recommendation based on your RV type.

• For the "Smart RV" Tech Enthusiast: Get the Mopeka Pro Check. Its ability to integrate with Victron and other 3rd-party systems makes it the most flexible and powerful choice for a truly connected RV.
• For the "Keep it Simple" Mainstream RVer: Honestly, still the Mopeka Pro Check. Even if you never use the high-tech integrations, its standalone app is the best all-arounder for anyone who doesn't have a Lippert system.
• For the RVer with a New Lippert-Equipped Rig: This is a no-brainer. Get the Lippert OneControl Sensor. The seamless integration into your RV's central "brain" is what you paid for.
• For the "Remote Monitoring" RVer (in storage): If you're willing to pay the subscription, the Generac LTE is the only one that will let you check your heat from 1,000 miles away. You can also explore Wi-Fi enabled RV propane monitors that bridge this gap.

Never Guess Again

Let's stop guessing. Running out of propane in the middle of a cold night or a hot shower is completely preventable. While those old-fashioned pressure gauges are, in my expert opinion, useless, modern ultrasonic monitors have changed the game. This is the whole point of smart propane monitoring for RVs.

The "best" monitor truly depends on your RV's existing ecosystem. Mopeka dominates for standalone use and high-tech integration, while Lippert is the clear and obvious choice for OneControl users.

But the real secret, as I've found over the years, isn't just which one you buy, but how you install it. Use spacers, use that dielectric grease, and enjoy the peace of mind that comes from knowing, not guessing.

Do you have a propane monitoring setup you love? Or a horror story about running out at the worst possible time? Share your experience in the comments below!

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Frequently Asked Questions (FAQ)

What is the most accurate RV propane monitor?

The most accurate type is a digital weight scale, like the Flame King, as it measures the exact weight. However, among the more convenient ultrasonic sensors, a properly installed Mopeka Pro Check or Lippert sensor is considered accurate to within +/- 5-10%, which is more than enough for knowing when to get a refill.

Will a Mopeka sensor work on aluminum propane tanks?

Yes, but not with the built-in magnet. You must purchase the Mopeka "Universal Mounting Collar" (Part #024-2001). This is a plastic ring that glues to the bottom of the aluminum tank to hold the sensor in the correct position.

Do I really need spacers for my propane sensor?

Yes, in 99% of cases. Most RV tank trays are flat, leaving no room underneath the tank. The sensor needs at least 1/2 inch of clearance to transmit its Bluetooth signal and to avoid being crushed by the tank's weight. Spacers (like the Mopeka Tank Halo) are essential for a good reading.

What's the difference between the Mopeka and Lippert propane sensors?

They are both ultrasonic sensors and work in a similar way. The key difference is the app. Mopeka uses its own dedicated "Tank Check" app and can also integrate with 3rd-party systems like Victron. The Lippert sensor only works with the proprietary Lippert OneControl app that runs the other smart features of your RV.

How long does the battery last on a Mopeka sensor?

The Mopeka Pro Check models use a standard, user-replaceable CR2032 coin battery. With typical use (checking the level a few times a day), the battery lasts 3-5 years.

Can I check my propane level from anywhere?

Not with standard Bluetooth monitors like Mopeka or Lippert, which have a range of ~50-100ft (you need to be near your RV). To check from anywhere in the world, you need an LTE/Cellular monitor (like the Generac) which requires a subscription fee, or a separate Bluetooth-to-WiFi bridge (which Mopeka also sells).