A few weeks ago, we put a new air conditioner on our Airstream. (The reason why is a long story, and perhaps will be the subject of another blog post.) It was about a $1,500 investment, and a fair bit of work too, since it was installed on a hot day in Arizona with the help of a couple of friends.
A few days later, we were staying in a campground in Santa Fe, New Mexico, in an exposed spot at the crest of a hill, with a sparkling view of the city lights below. In the afternoon, fierce thunderstorms began moving in, and the lovely fall weather began turning into a dark and scary night. We battened down the hatches and settled in for a quiet evening of leftovers and a movie.
Outside, the temperature dropped to the low 50s as the storms came overhead, and heavy rain rattled the aluminum roof, to the point that we wondered if hail was coming next. Inside, the furnace was running, and our windows were fogging up as the interior became humid.
I decided that this was an opportunity to try a feature of our new air conditioner: dehumidification mode. In this mode, the air conditioner runs at a low level to remove moisture without cooling.
It worked beautifully, and soon the fog on the windows was fading, which allowed me to see the Progressive EMS on the power post outside the bedroom window. We always plug our Airstream into this device, to protect the Airstream and all of our devices from power surges, brownouts, and wiring problems.
And then it happened. With absolutely no warning, the power went out.
The air conditioner and convection microwave (in use at the time) shut off. Of course, the 12-volt powered devices in the Airstream remained on, so it wasn't quite as dramatic as a power outage at home, since we still had lights and our movie kept playing. But still, it was pretty unexpected–especially since this was fall, not summer, and the torrential rain had begun to lighten.
I looked out the window through the rain and saw the display on the Progressive EMS flashing its sequence of red numbers:
E0 ... PE4 ... 122 ... 0A ... 60H
The sequence told me:
The power is currently good (error code 0), we have 122 volts at the power pedestal, the trailer is currently using zero amps, and the frequency is normal at 60 Hertz.
The "PE4" was the really interesting part. It means "Prior Error code 4" which indicated that just seconds before, the campground voltage had dipped below 104 volts!
In other words, we had had a brownout, which the EMS thankfully saved our Airstream from.
Brownouts are really bad news for RV air conditioners
Low voltage can quickly cause the compressor to burn out. Without the Progressive EMS we would have been buying another $1,500 unit to replace the one we'd installed just days before! But our trusty EMS had done its job by shutting off the power before any damage could be done.
A surge protector would not have saved us
That's because we didn't have a sudden ZAP from a lightning bolt. We had a slump in voltage. Basic surge protectors can't help with brownouts, so they are a really incomplete protection.
The EMS kept the power off for 136 seconds, as it is designed to do, while it verified that the power supply was again safe to use. And then, the dehumidifier came back on, and we went back to microwaving the leftovers.
In other words, no drama.
The brownout was a non-event, simply because we had the right equipment. This is why I always tell people the same thing about having an EMS and a Tire Pressure Monitoring System: "It's like insurance. You don't need it—until you do, and then you're very glad you bought it."
12 comments
Randall Godfrey
I would like to hear the story of why a new AC and what brand you chose. My Dometic has been running with no issues other than a start capacitor since it was new in 2014, but I have been wondering when it may give up the ghost.
Greg
…good write-up, Rich. Would an Autoformer saved you from dealing with the brownout by boosting the voltage, thereby keeping your power up and running? Just curious. Thanks.
Rich Luhr
Greg — an autoformer would boost the voltage, but in this case I don’t think it was what we needed. The storm was playing havoc with the power all night. When we woke up in the morning we found another power glitch had occurred: a momentarily lost Ground connection. (We knew because the error message on the Progressive EMS had changed from PE4 to PE2.) This situation called for FULL protection against all possible types of power glitches.
Generally speaking I’m not a fan of autoformers. That’s a deeper subject than I can address in a blog comment, but perhaps I’ll write about that in the future.
Rich Luhr
Randall: I will definitely write more about air conditioners, and our experiments with the new energy-efficient models, in the future. Right now the situation is a bit murky for Airstream owners, particularly those with ducted air systems. This is due to incompatibilities and complications arising from the way the original air conditioning systems were installed.
Suffice to say that our test installation turned out to be much more complicated than we expected, and required a lot of “work-arounds” to complete. Still, I’m confident there will be a much easier path forward once some installation kits and instructions are developed. I am currently working with one of the manufacturers directly to solve all the technical problems, and will definitely post an update once we have a solution that is “ready for prime time.”
Claudia
Great info and story, thanks. I need to check the capabilities of our thingy at the post.
We have a victron multiplus II in our 50A airstream. Would the power support mode have saved us in a situation like yours?
Rich Luhr
Claudia: The PowerAssist function of a Victron Multiplus might have been helpful to compensate for the brownout, depending on how it was set up. The UPS function would have to be enabled.
However, a Multiplus is not designed to protect against power spikes, mis-wiring, or loss of ground connection, so it’s not a true substitute for an EMS.
Klaus Wessel
Hi Rich, thank you for sharing the experience and the advice, good as possible. It is related to my deep mistrust to pedestal electricity.
May be you can answer two additional questions:
Does the EMS provide the similar functional protection as an addional on-board AC-breaker would provide.
Does the EMS protect against fluctuations of AC frequency, which may be a symptom of a brownout?
Thank you
Klaus
donald wright
thank you. I need to learn and understand the code.
Rich Luhr
Klaus: Good question. The EMS (outside, at the power pedestal) and the circuit breakers (inside the RV) have different functions.
A circuit breaker will shut off power when too much current is being pulled. This might be caused by a short circuit in the RV, or too many appliances on at once. A GFCI-equipped circuit breaker adds additional protection against possible shocks to people. These are primarily features to protect the RV from its own problems.
The circuit breaker doesn’t do much to check or protect against issues with the campground wiring. That’s where the EMS steps in. It detects problems with the campground power, such as mis-wiring, missing ground, low/high voltage, and yes— fluctuations in frequency.
Rich Luhr
Donald, all the error codes for the Progressive EMS can be found in the owner’s manual as well as in our Help Center.
https://air-gear-help-center.gorgias.help/en-US/the-display-screen-is-showing-an-alphanumeric-code-what-does-it-mean-229373
Darren C.
Do you recommend using a EMS during generator power hook up. I usually use two 2200 Honda generators & parallel them together. I am wondering if one generator runs out of gas during the use of a 30 amp AC unit; would the same issue happen like a brown out. Should I always use my EMS during generator use and shore power? Thanks for the feedback.
Darren C.
Rich Luhr
Darren C: There’s no harm in using your EMS with your generator, but be aware that the Progressive EMS will show an E2 error code, which means “open ground”. You’ll want to buy a “generator neutral-ground bonding plug” to plug into one of the generator’s outlets. This plug will fix the issue.
If you are running two generators and one stops running, the voltage output from the remaining generator should remain steady, at least until the air conditioner compressor cycles on again. At that point, the generator will probably be overloaded and quit running. A good work-around for this problem is to install a Micro-Air EasyStart (which you can find in the AIR GEAR store).
The EasyStart will reduce the big current spike caused by the air conditioner’s startup, and will usually allow you to run a single RV AC on a single Honda 2200 watt generator.