Some truck camper owners have pass-through type inverters, meaning shore or generator power passes through the inverter on its way to the camper’s main AC panel. It’s in this way that upon loss of shore (or generator) power, the inverter picks up the load in mere milliseconds (typically about 16 ms) through its automatic transfer switch, which is fast enough to prevent even the TV from flickering. To put it another way, the inverter when it’s resting in the “standby mode” also serves as a “power sentry” that can qualify or disqualify deficient incoming power due to a lack of, or improper voltage and/or 60 HZ frequency.
Inverters with automatic transfer switches, like my Xantrex Prosine 2.0, work well, and can truly help prevent damage to delicate electronics including refrigerators and air conditioning motors due to voltage sag at the campground—which common in the summertime—or in a scenario when using an undersized generator.
Though this strategy normally works quite seamlessly, it doesn’t really mesh all too well when using a smaller 2,000 or 2,200 watt generator set to a lowered RPM Eco mode. Why? Because the inverter sees the generator’s low RPM and sluggish load response as “defective power” and quickly intervenes via the auto transfer switch and takes over the entire load, thus beginning the dreaded “to-and-fro” inverter-to-generator cycling scenario. Ugh! To prevent this from occurring, one is left to running the generator in its regular non-economy mode, meaning unnecessary noise and poor fuel economy.
After ruminating over a solution for months, which included some exhaustive test meter evaluation, and after having installed a compressor “soft-start” device, I finally realized that the culprit to this nagging malady was due to the inverter—it was simply doing what it was designed to do by disqualifying “suspect” generator power. Admittedly, this finding was quite unexpected to me since I’d never had this problem with a previous inverter (i.e. essentially inverter out of the loop), and it’s no secret that tons of folks routinely run similar air conditioners while running in the eco-mode.
Ultimately, the fix for my Eagle Cap 995 camper was to install another automatic transfer switch (a Progressive Dynamics 5100 Series 30 amp model) between the main panel, just ahead of the air conditioner, along with a dedicated generator “eco mode” power cord. When using this new power cord with my Honda EU2200i, the camper’s remaining 120 volt system is bypassed and the air conditioner works just fine. And thanks to the new Progressive Dynamics transfer switch, if I were to turn the inverter on to, say, run the microwave while concurrently plugged into shore power, there are no conflicts between the two independent AC power sources. Better yet, if the generator for some reason were to shut down, the new transfer switch simply hands-off the air conditioner load back to either the inverter (assuming it’s in standby mode) or to shore power.
Oops, Sorry for my belated response, I just got your message!
Yes (unless I’m misunderstanding..), what you’re basically experiencing is a nagging ‘round robin affair’ whereby the inverter is drawing from your batteries while simultaneously trying to charge them (ugg!!)…And, per your description I’ll assume that you also have a 120v ‘pass-thru’ type inverter…
If so, an effective way to resolve this issue would be to ‘tap into’ your camper’s existing shore-generator power ATS* switch’s 120v OUTPUT LINE (*assuming you have a generator) – i.e. the line that normally goes to the camper’s main service panel …
You do this by inserting a ‘new connection point’ junction box (J-box), into where this line leads to the main panel…This new J-box will enable you the addition of a second parallel output line – this one dedicated as the inverter’s new 120v input (reconfigured from the previous scheme)…To recap, this new J-box will be suppling both the main service panel, AND serve as the inverter’s sole AC input…
Next, now add a small sub-panel (say, possibly behind the cabinetry…), this is ‘the new home’ for relocating ‘certain’ circuit breakers (meaning, circuits of your own choosing – often the MW, house receptacles, air cond, etc.) from the main panel to the new sub-panel…You might now sense the purpose here is to achieve two parallel, ‘passive cascading’ systems – meaning, one (inverter in standby mode) that provides shore-generator power to power-up EVERY camper 120v circuit, as was before, while restricting inverter, off-grid operation to the essentials of your choosing…
I hope this provides the right answer to your question.
I’ve had the same problem for years, but with a Westinghouse iGen 4500 inverter/generator, in our 5th wheel. I assumed it was a generator component problem. Now we’re adding a Host Yukon TC to our travel routine & parking the 5th wheel as a home base. With the 5th wheel permanently on shore power, it won’t be a problem anymore, & the TC has Host’s extreme solar package with 760 watts of solar, & 720 amps of lithium power. I didn’t even order a generator with it, because I don’t anticipate a need for one. But the generator problem we experienced for years was very frustrating, because we did a lot of off grid camping in the 5th wheel.
Thanks for the article! I have a question that I have been trying to figure out for a while. I have a Xantrex with a transfer switch. When I run shore power, the transfer switch works and i feed off of shore power. the problem I’m having is when i run off of my 400ah Battleborns through my Redarc Maneger 30, my 4WC system reads the power as as shore power and loops back to “charge” my batteries. this causes an extra draw and i use more power then I should be. I do have a switch on the 4WC that i can throw that stops the feed back to the batteries, but it would be nice for it to be seamless. Ideas? Another transfer switch??