Automatic Transfer Switch, a supplemental ATS for running HVAC on Inverter

[jd1923]

Not happy with recent purchase of a KISAE ATS 20. Could they give you another 1/2" in the terminal area? It is very difficult to wire. To tighten the terminals, you need a micro-size flathead screwdriver. Another bad, this is a 20A switch that should have standard terminals like in the 30A power panel.

Some pics to follow. The first one is the OEM Xantrex ATS used to run all AC circuits less the air conditioner. Wonder if Xantrex has a 20A version of this? It must be better. Or... maybe given a likely upgrade to a modern RV A/C system needing only 10A, we then would only need a 15A ATS.

The switch as installed will actually run the old Dometic Penguin II A/C running off the inverter. (See pic 4, it started at 1400W and after 5 minutes was running at 1800W.) I did see an occasional error code on the 2KW Xantrex. I still have lead acid batteries, so the error could have been running just under 12V for a second. The reading was 12.1V most of the time under this heavy amperage. You truly need LiFePO4 batteries to run the A/C off inverter. I was hoping to get this inexpensive installation done now to be ready for future HVAC and LiFePO4 upgrades. Pic 3 shows the switch in the bottom righthand corner taped to the top of the power panel (original cable in and new 12-2 cable to the panel).

It will NOT run the A/C on 120V shore power, go figure. It could be a bad switch, or it could be I have an open wire on the input side that connects to the 20A A/C breaker on the panel. I hate to have to open this and wire it again. First thing to check is for continuity of the hot, neutral and ground, from the panel and left to right across the switch. I'll report on this later.

Of course, while I'm doing this there is no air in the Oliver! I truly would like to find another brand inverter ATS. Please don't run out and buy one of these in a hurry.

Edited June 24 by jd1923

[Ronbrink]

6 hours ago, jd1923 said:

It will NOT run the A/C on 120V shore power, go figure. It could be a bad switch, or it could be I have an open wire on the input side that connects to the 20A A/C breaker on the panel. I hate to have to open this and wire it again. First thing to check is for continuity of the hot, neutral and ground, from the panel and left to right across the switch. I'll report on this later.

Of course, while I'm doing this there is no air in the Oliver! I truly would like to find another brand inverter ATS. Please don't run out and buy one of these in a hurry.

Is your KISAE TS plugged into the inverter? The install in my unit was very straightforward; simply spliced the KISAE TS into the existing 12-2 Romex from the breaker box and plug it into an inverter supplied power outlet. Yes, the terminal connectors seemed inadequate, but suffice; I had issue with the extremely short power cord on the KISAE TS, really limited positioning. Good luck with your endeavor!

[mountainoliver]

I used this transfer switch for running my air conditioner through the inverter. Only two cables no issues getting the switch wired. I did change out the cheap plastic wire strain relief bushings for standard metal clamp type bushings. The cable on the right comes from the power distribution panel and the one on the left goes to the air conditioner. I’ve checked the terminal strip screws on several occasions and they’ve always been tight. Don’t try to use the Zantrex 15A switch, it’s just enough to run the Penguin AC Unit but gets pretty warm after a few minutes even with the soft start module. I switched over to three Battle Born batteries a few years ago and they can run the AC unit for maybe a couple of hours, although I’ve never run it for more than a half hour or so because I haven’t wanted to totally deplete the batteries. My 320 watt solar system would take several days to completely recharge the batteries. The 2,000 watt inverter seems to handle the load well but, I make sure that there are no other DC loads at the same time. 

Edited June 24 by mountainoliver
Clarification

[jd1923]

Thank you @Ronbrink and @mountainoliver, I was made aware of this solution and the KISAE ATS 20A from posts you made previously.

I must have one wire on the Input side off (from the breaker panel/shore power). The output side must be fine since the A/C is running on inverter. Where I mounted my box the power cord just makes it straight down to the inverter. I'll check the wiring today. It's not a good design where you cannot physically see the wire connections and the screw dia is barely wider that the wire gauge. Changing to standard metal clamp type openings would also make the wiring easier. I'll get it today unless the ATS is defective.

My 2KW Xantrex inverter got rather hot running the Penguin for <8 minutes and I don't plan to do that again. This will be for when we upgrade to a new more efficient air conditioner. My plan also includes 900 AH in Epoch LiFePO4 batteries. A final upgrade in future years would be a 3KW inverter, hopefully one with hardwired 120V terminals and built-in ATS.

[jd1923]

OK so this is going to get strange! I went out to test the ATS today and IMHO the testing shows a bad switch. An ATS must have a fail-safe design in that if it's unplugged, or the inverter fails, or whatever condition, the AC input line to output/load is connected, a closed pass-through connection must be the default position (should always be able to run via shore power).

First, I disconnected shore power and tested for continuity left to right across the switch. The ground had continuity and both the hot/load and neutral terminals did not have continuity. I unplugged the ATS and had the same test results. Then I tested continuity from the 20A plug to the terminal leads. Again, ground to ground was good. However, the two plug posts showed continuity to BOTH hot and neutral terminals. I would think one should connect to one, not one connecting to both hot and neutral terminals. This must be wrong.

Next test was to see if the new 12-2 line from the power panel (the hot through the 20A A/C breaker switch) showed continuity through the terminal screw heads. This would show the wires from the panel were connected properly at both ends. All three connections tested positively for this cable.

Then I connected to shore power to see if the switch was getting nominal 120VAC. As I climbed into the Oliver the air conditioner started running! It had been connected for the last 24 hours, and it would not power on. Maybe my continuity testing reset something, but this is unacceptable quality.

It had gotten up to 89 degrees inside. I'm inside the house now and my RUUVi says it has dropped 6 degrees in the last 45 minutes. I had thought that during the install, it did run once via shore power and later after running by inverter it would not. In fact, I turned the inverter off while the A/C was running and it just quit, where it should within milliseconds switch over to shore power while keeping the compressor running. The sole purpose of an ATS is to switch seamlessly in either direction.

Before it had powered up, I placed a call to KISEA and left a voicemail re the continuity testing and asking for a replacement switch. Can't wait to wire another one of these!

[jd1923]

Ricardo from KISEA left me a voice message. He said there should NOT be continuity across the terminals unless the input terminal shows >100VAC. That does make sense to me now. No shore power then only the inverter circuit is available through the ATS. 

It has a solid 120V and continuity on both sides of the ATS terminals now that it is reading voltage. It seems the ATS is working now, so I'm not sure what to do about the intermittent issue I've witnessed. Why was it not working for 24 hours. Did it somehow reset when I had shore power disconnected for 30 minutes today? Will it get stuck open again? Good thing we are not traveling soon.

[Ronbrink]

14 hours ago, jd1923 said:

OK so this is going to get strange! I went out to test the ATS today and IMHO the testing shows a bad switch. An ATS must have a fail-safe design in that if it's unplugged, or the inverter fails, or whatever condition, the AC input line to output/load is connected, a closed pass-through connection must be the default position (should always be able to run via shore power).

For whatever it’s worth, I’ve only run my A/C via the inverter when not hooked up to shore power. Not sure it can even be done when hooked up. 

Edited June 25 by Ronbrink

[mountainoliver]

I also have never run my air conditioner on the inverter if the trailer is on shore power. In fact I never turn on the inverter if the trailer is already on shore power. I’ve never had a reason to, either the trailer is on shore power or not. I know some folks leave the inverter on all the time and that really shouldn’t hurt anything but I don’t. 

[jd1923]

Agreed, the way the KISEA ATS works is when shore power voltage is sensed it will use that source regardless of whether your inverter is on or not.

In the past, I had often kept the inverter on. Let's say you want to keep 120V circuits on when breaking camp or changing location (keep the TV on, run the microwave, etc.). Another reason is for power backup. If you lose shore power (a black or brown-out) the inverter will seamlessly kick in and keep all your 120V appliances running! We've often parked at campsites without connecting to shore power. When A/C is not required and you have ample solar/batteries/inverter, why bother?

Now that this ATS is wired, you must realize the A/C can also come on which is a very different consideration. The penguin is too much pull on a 2KW inverter. Given good AH capacity in LiFePO4 batteries and a more efficient A/C system, all should be good. If you do not want the A/C to run while on inverter, you must turn off the A/C via the thermostat or trip the breaker.

I did this installation in advance, for when I upgrade batteries and A/C. Until these upgrades are implemented in our Oliver, this ATS has no true purpose. Now that I have this experience, I believe I should have waited. What if the Xantrex fails, or I decide to upgrade the inverter? If so, this was a waste of time and $84 (but a good learning experience).

A modern 3KW inverter/charger would of course replace the Xantrex 2KW inverter, and the PD charger (built into the power panel, and ours is the old version, not LI capable). It would also replace the KISAE ATS. For example, the Victron 3KW inverter/charger (given a viable location can be found, since it's much larger) has a built in 50A Automatic Transfer Switch (ATS) which can easily power the 30A 120V AC panel in the Oliver. I did not realize all this just a few days ago.

[jd1923]

6 hours ago, Ronbrink said:

For whatever it’s worth, I’ve only run my A/C via the inverter when not hooked up to shore power. Not sure it can even be done when hooked up. 

If you want to run it via inverter, say for testing purposes, you merely have to trip the 20A breaker for the air conditioner. The KISEA will sense no shore power voltage and connect the inverter to the A/C load wiring.

[Ronbrink]

26 minutes ago, jd1923 said:

The penguin is too much pull on a 2KW inverter.

My Dometic 11,000 BTU A/C with Micro-Air EasyStart works fine with the Xantrex 2000 in my unit. The max run time thus far on inverter is 2 hours.

Edited June 25 by Ronbrink

[mountainoliver]

jd1923 I agree 💯. I basically did the same thing. I added the automatic transfer switch for the air conditioner and several months later switched to lithium batteries. However, I have not had any issues with running the Dometic air conditioner on the inverter. It does get warm but as long as my total watt load does not exceed 1,800 watts the Zantrex inverter should handle it. The specs say it is capable of handling 1,800 watts continuously and 3,000 watts intermittently. I have run the air conditioner for about a half hour and the inverter was very warm but I wouldn’t say that it was hot. It does have an overheating shut down sensor and it has never shut itself off for any reason. At some point in the future I plan on getting a 3,000 watt inverter but I’m not interested in one that also incorporates a charger as well. As of now I only use the air conditioner to cool down the trailer in the evening then open windows overnight unless we’re on shore power, then the air conditioner stays on if necessary. 

[jd1923]

52 minutes ago, mountainoliver said:

At some point in the future I plan on getting a 3,000 watt inverter but I’m not interested in one that also incorporates a charger as well.

It appears today most models are inverter/charger. Please allow us to understand your reasoning. I can see an inverter failure in an inverter/charger combo unit could keep the charger from working as well. But they should be designed to run and fail independently. Do you have other reasons. This is a good thought to consider and we're all here to learn.

Also, it appears given your older hull number that your Dometic is the 13.5K unit? Good to hear it runs OK, so my limiting factor is the LA batteries that almost immediately go down to near 12V with the 1800W demand. Thanks

[MAX Burner]

1 hour ago, jd1923 said:

We've often parked at campsites without connecting to shore power. When A/C is not required and you have ample solar/batteries/inverter, why bother?

BINGO, brother!  Our power cord only saw the light of day during this trip until DAY-11.  Fortunately, our route had us going into the northern high-country of WY and UT and eastern ID - in some cases, mid-30's at night.  We've only cranked up the Screaming Penguin on Sunday due to the low-mid 90's here in Huntington, UT - thankfully, its mid-60's a night for good sleeping temps w/o the AC grinding away.

[Ronbrink]

2 hours ago, jd1923 said:

If you want to run it via inverter, say for testing purposes, you merely have to trip the 20A breaker for the air conditioner. The KISEA will sense no shore power voltage and connect the inverter to the A/C load wiring.

My only real dilemma is when in storage on shore power and I want to run the A/C when doing maintenance or cleaning, which the facility’s 15A shore power will not allow. Before LFPs, I would run a generator on propane to enable use of the A/C, now the process is much simpler! When needed, I generally just unplug the power cable and run the A/C via the inverter. Away from storage I always have 30A service, either at home or a campsite, and can run the A/C on shore power. The above described scenario is only one reason for wanting to be able to run the A/C on battery, but the primary reason was for use when underway during stops for rests and/or meals. You know the gig!

Edited June 25 by Ronbrink

[Ronbrink]

2 hours ago, jd1923 said:

It appears today most models are inverter/charger. Please allow us to understand your reasoning. I can see an inverter failure in an inverter/charger combo unit could keep the charger from working as well. But they should be designed to run and fail independently. Do you have other reasons. This is a good thought to consider and we're all here to learn.

Case and point, my Xantrex 2000 is an inverter/charger. The inverter works as intended, however the charger (80A) only has an initial charge cycle which comes on when first plugged into shore power. Since there is no further charging capability, it necessitated my going to the storage facility almost weekly to reboot said charging cycle by unplugging from shore power and reconnecting. This task was really worrisome with the former four 6V Trojans to prevent discharge below 50% SOC, but not as much now with my 460 Ah LFPs that can take a deeper discharge and have double usable amp hours. To rectify the inherent problem, I recently installed a Victron Cerbo and 30A Smart Charger to assume the task of keeping the battery bank SOC in check. On Auto Start, if my SOC drops below 60% the charger is activated and set to turn off when 95% SOC is reached. There is also a Manual Start and Off mode; all done by way of the VictronConnect app.

NOTE: I did talk with a Xantrex tech about the charging aspect and he confirmed it was not operating correctly; he recommended purchase of a new unit. 

Edited June 25 by Ronbrink

[mountainoliver]

jd1923, maybe a couple of reasons to want a separate charger/inverter. My older hull number trailer has separate units already and it all works well so I’ll probably just leave well enough alone. Also, seems like the newer trailers with the combined units are having issues with both. If one unit goes down nothing works. I seldom ever turn on the charger anyway, I let the sun do its thing. Seldom use my generator as well. We’ll plug in if it’s available, sometimes. Really the only thing that must be plugged in is the air conditioner, everything else can run comfortably on either DC directly or on the inverter. The only situation that we would have had a problem is when we were caught in the Texas deep freeze about four years ago. Several days with little sun and highs in the twenties and lows in the single digits. Fortunately we had shore power the whole time. It’s a blessing to be able to own a trailer that is set up so that it really doesn’t matter if we have power or not and can easily allow us to camp most anywhere. I love it when a campground apologizes for not having a site with water or electricity and being able to say that it doesn’t matter we’ll be comfortable anywhere. 

[MAX Burner]

1 hour ago, mountainoliver said:

It’s a blessing to be able to own a trailer that is set up so that it really doesn’t matter if we have power or not and can easily allow us to camp most anywhere. I love it when a campground apologizes for not having a site with water or electricity and being able to say that it doesn’t matter we’ll be comfortable anywhere. 

Excellent point, brother!  We like having that conversation at RV parks as well - it usually comes with a discounted nightly rate, too...