Automatic system restart for air con

[Bluedog225]

The big picture is that I’d like to set up an air conditioner in my cabin. And I’d like it to auto restart if I ever run the batteries down to the recommended 48 volt disconnect. All off-grid.

Until construction is complete, it’s going to be a window unit. I’d like it to run 10 hours a day. Roughly 10 am till 8 pm. I’ll adjust based on real life power available. It’s going to get very hot this summer and I’d like to keep the whole place as cool and dehumidified as possible.

The midea 12,000 btu window unit uses about 1200 watts. I can throw out about 5000 watts in panels, and I have 4 SOK rack batteries, Quattro 48/5000, and cerbo.

Here’s the sequence that’s I’m working on:

1. System charged and running normally.
2. Cloudy days-system disconnects at 48 volts.
3. Sunny day-Batteries charge.
4. Quattro attempts 3 restarts when voltage (?) rises.
5. Air conditioner load prevents restart and Victron requires manual start. OR Air conditioner requires manual restart. OR Air conditioner on a separate timer (assumes air con will restart when power available).

Questions:

1. Does anyone know if the midea window units restart when power is restored? I didn’t see anything about this in the manual.

2. It looks like the SOK batteries have a low voltage disconnect. But is there also one in the Quattro ecosystem? Or do I need to buy a Victron battery protect?

3. Has anyone set up a clever timer that would work in a situation like this? The best I can think of is a separate timer on a 12 volt battery with a relay to the air conditioner. It would open and shut down at a set time each day. Without regard to whether the Quattro was providing power.

It’s starting to feel like I need some “smart” home tech. But the low voltage disconnect is going to be a problem.

Any ideas on how to get this done welcome.

Thanks

 

[sunshine_eggo]

The big picture is that I’d like to set up an air conditioner in my cabin. And I’d like it to auto restart if I ever run the batteries down to the recommended 48 volt disconnect. All off-grid.

1. System charged and running normally.
2. Cloudy days-system disconnects at 48 volts.
3. Sunny day-Batteries charge.
4. Quattro attempts 3 restarts when voltage (?) rises.
5. Air conditioner load prevents restart and Victron requires manual start. OR Air conditioner requires manual restart. OR Air conditioner on a separate timer (assumes air con will restart when power available).

If you're getting an inverter A/C like the "U" shaped one, there is no surge, so #5 would be mitigated.

Something that might be useful is a smart wi-fi plug. You could have one that is only on during certain periods, or simply turns itself on at a given time every day, with no shut off. This is useful because these devices typically stay off in the event of a power failure. You could then have it automatically turn on at 10am every day. This would mean if the inverter shuts down, the A/C stays disconnected until 10am the next day.

Questions:

1. Does anyone know if the midea window units restart when power is restored? I didn’t see anything about this in the manual.

Can't help.

2. It looks like the SOK batteries have a low voltage disconnect.

Avoid this. Do not use BMS to engage discharge protection above the 2.5V/cell default.

But is there also one in the Quattro ecosystem?

Yes. Inverter settings.

Or do I need to buy a Victron battery protect?

No!

 

[Bluedog225]

Good info. Thanks.

 

[chrisski]

Will the Quattro manually start a generator and would you Do this?

5 kW of panels, 20 kWh of batteries, and a Quattro is a decent plan, at least for the summer in my area, don’t know the weather for yours?

 

[Q-Dog]

The Midea U has the ability to follow a schedule. I have not used it so I have no idea how it remembers time or what happens when the power is shut down.

But I have turned it on and off and made adjustments remotely from the app.

 

[Bluedog225]

Will the Quattro manually start a generator and would you Do this?

5 kW of panels, 20 kWh of batteries, and a Quattro is a decent plan, at least for the summer in my area, don’t know the weather for yours?

Hot, and humid. But mostly hot.

I don’t plan on using the genny. Too much setup, fire, and security issues while I’m away.

I’m trying to find a smart plug that has a memory feature that would survive a power outage. And one that doesn’t require a WiFi network to operate.

 

[wpns]

4. Quattro attempts 3 restarts when voltage (?) rises.
5. Air conditioner load prevents restart and Victron requires manual start. OR Air conditioner requires manual restart. OR Air conditioner on a separate timer (assumes air con will restart when power available).

Is this a known problem, or are you asking if this will be a problem?

 

[HalfBaked]

It seems you could use an old fashioned analog timer for this. The kind that looks like a clock that you set pins for on/off at certain times. It only works when the power is on.

In your case, you could set the pins to power the unit on every hour or half hour without using the "off" pins.

The timer will attempt to power the unit every hour when power is available. If unit is already on, the timer will do nothing.

 

[Bluedog225]

That’s not a bad idea (the timer). Though I was thinking i wanted to run mostly during peak production hours.

Does anyone know when the Victron attempts it’s three restarts? Is it in rapid succession or does it wait till it senses there might be power available?

 

[Bluedog225]

Is this a known problem, or are you asking if this will be a problem?

Not a problem. I am trying to understand how the system will behave though out a daily and weekly cycle.

 

[Danke]

I would doubt a digital controlled air conditioner would turn back on with power disconnected and reconnected. One advantage of the old analog dials…

 

[Bluedog225]

I think you are right. Though refrigerators etc turn back on.

 

[Danke]

I think you be right. Though refrigerators etc turn back on.

I tried it on a space heater and it didn’t work. So I had to buy one that had dials for my pump house. I’m going to try it now on the digital air conditioner and see what happens.

 

[Bluedog225]

I don’t Facebook but found this. Looks like the mini split has auto restart

 

[Texas-Mark]

1. Does anyone know if the midea window units restart when power is restored?

I would doubt a digital controlled air conditioner would turn back on with power disconnected and reconnected.

My Midea does. That is one of the reasons I got it. I have my inverter set on a timer. When the inverter turns on, the AC comes on. The AC has a compressor delay, so the inverter comes up to speed well before the compressor kicks it. The AC also remembers the last temperature setting even if power is removed.

 

[Bluedog225]

Thanks Mark.

And the manual seems to agree.

 

[Danke]

OK, tried it on the cheap Denali window air conditioner. The fan came back on, but not the compressor…

 

[Texas-Mark]

OK, tried it on the cheap Denali window air conditioner. The fan came back on, but not the compressor…

Did you give it enough time for any compressor delay?
But I agree not all of them will work. The old one I had in there did, but that is because it had manual knobs. When i decided to change it out, I specifically looked for one (digital) that would.

On a side note, in my trailer, I have a small 300w inverter that stays on all of the time. It powers my long range wifi antenna (to get wifi from my house) and Kasa smart plugs. Then I modified a Kasa smart plug to be a dry set of relay contacts. I use the timer function of that switch to turn on the big inverter that powers the AC. This way I can also remotely turn the AC on/off too regardless of timer settings.

 

[wpns]

My Mitsubishi and Lennox mini-splits come back on (after a10(?)-minute compressor delay) when power is restored after it fails.

 

[Danke]

Did you give it enough time for any compressor delay?

The compressor came on right away when I first started it. I did wait a few minutes after I plugged it in for the compressor to kick in. I cycled the on/off switch to on and the compressor came on. But maybe I should’ve waited longer when I plugged in and it would’ve eventually come on?