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Everybody wants to know what they need to get their air-con running off-grid and how long it’ll run for.

Hi, I’m Andrew, here from Accelerate Auto Electrics showing you what you can do for off-grid air conditioning and how long you’ll get out of it.

Okay, so I’ve put together an experiment today. I’ll give you some precursors. I’ve made this as simple as I can. My intention with this video is not to baffle everybody with acronyms and all the confusing terms. It’s to put together a really simple video, running air conditioning off some AGM batteries and showing you how long a run time you’ll get out of it, and the differences between it.

We continually get asked, how long will my air conditioning run? 

How big a system do I need?

The reason why no one will answer that question is because it totally depends on your expectations and you monitoring the system yourself, and this experiment is gonna explain why if you monitor it yourself, you can actually get your air-con running on quite a budget system with some smaller things. 

Setting Up The System

So to put this video together, I have disconnected the solar, so that we’ve got nothing running in. I’ve also just dropped this system down. We’re only running off three 120amp AGMs. So we got 360 amp hours of AGM batteries. We’re running through an Enerdrive E-Pro 2000 watt charger inverter, but it’s not on charger mode.

So basically, the simplicity of this system is three batteries, an inverter, and a Dometic Harrier. So what I’m gonna start off with as we do this, is here we have, it’s sitting, it’s thinking, it’s got 142 hours, ’cause we’re only drawing one amp so we’ve got a few lights going on here.

As we turn the air conditioner on, what we’ll see, so we’re gonna drop it down to 16 degrees. So it’s gonna take a bit of time to ramp up. Initially, you can see where, at the moment, we’re only, it’s coming at 20 amps, and that drops our run time to 7 hours. Now you have to understand, if we had the solar connected, we could be putting in up to 25 amps at the moment ’cause we are in the middle of the day. So that would be offsetting it. 

I want you to think of it all as the battery’s a bucket, the air conditioner, a hole in the bucket, and our solar filling up the bucket. So basically, what we got here is as it’s slowly starting to ramp up, we’re starting to get cold air, we got 30 amps. Now what a Harrier will do, we’ve just jumped to 46 and you see we’re only showing two hours run time. So you may be thinking, oh he’s only gonna get two hours out of this battery, these batteries, what a waste of time, but the truth is, and it dropped below two hours now, the truth is once this comes down to temperature, if we monitor our actual temperature setting, we can get this thing to run right back at about 20 amps, which would give us up to five to six hours with this system.

So I’m putting this video together, we’re gonna come and go a bit, and the change the settings, ’cause each time, there is a bit of a lag time as the air conditioner winds up and winds down, but we’re gonna go through different settings, show you what it’s actually drawing, and show you that if you put a system together and you monitor it as you use it, and you have realistic expectations, understanding that it’s gonna be different depending on the temperature of the day, the humidity of the air, whether your van’s in solar, in sunlight, whether your solar’s running, the time of the day, you can actually quite effectively run your air conditioning system off a smallish battery bank.

We do a lot of very large systems and that gives you the basic benefit of just being able to run it whenever you like and have a big bucket to be able to fill, but this is, you know, just a lot of people don’t have the budget for that. 

So we’re showing you how we can run it off a small bucket, with a smaller budget. You just have to mindful of what it will do and have your expectations set accordingly. So again, it’s still ramping up, but it’s pulling about 60 amps now. I think we’ll bump up the fan a bit ’cause we should be able to get more out of it. When these things are flying, they’ll pull nearly 80 amps. 

There we go, we’ve just gone to 65 at the moment, and you’ll see we’ve dropped to an hour and a half.

What I’m gonna do is I’m just gonna cut away for a moment. I’m gonna let it run for about 10 minutes, and then I’m gonna start adjusting, so I let the van cool down, and then I’m gonna start adjusting the temperature setting on the Harrier, and you’ll see that we can achieve a much greater run time with the battery bank we’ve got.

After 10 Minutes

All right, guys, so it’s been 10 minutes.

Now we’ve been letting this thing run flat out. I will tell you it’s nice and cool in the van now. We’ve cooled the entire van down. We’re still drawing 70 amps, and it’s showing that we’ve only got one hour, 21 minutes to go. Now again, remember we’ve got no solar running, and we’ve got a small bank of batteries just so this will all happen quicker, and we can do a better demonstration.

I forgot to note this is the Jhub, so this will come standard with a high-end Jayco, and that’s pretty much, why we’ve used this because it’s a nice gauge and it shows a run time, and it’s a nice, simple way of doing it. I should point out, I’ve intentionally used AGM batteries as well, so we can have a fluctuating voltage and we can monitor the voltage as well. Obviously, if we’re using lithium, we’d have a consistent voltage, and it would be harder to monitor this system as we go.

So we’re sitting on 16 degrees, fan flat out, and we’re in a cool van. It’s showing us only an hour, 20 minutes left and we’re drawing 70 amps. What I’m gonna do, pretty much like everyone recommends, in home air conditioning for energy saving, I’m gonna drop it to, it’s sitting on 21 degrees now, and I’ll wind the fan back one click. 

So now we’re running the fan on half-speed. This will take a bit of time. You’ll notice it’s probably a bit quieter in here. There’s a reason why they call them a Harrier, and instantly, it’s gone from 70 amps, and now it’s currently sitting on 52. What we’ll find, and we’ve dropped below 50, the amperage now will drop down.

So, in a real-world situation, if it was the middle of the day, and you had the van all closed up, we’ve got a few windows open for recording, van all closed up, solar on the top working, pulling like 15, or in this van’s case, it can pull nearly 30 amps. We’d actually be almost inert, and continuing, we’d be sort of running autonomously. So it’s gone down to 42 amps, and what we’ll find, the longer we wait, the more patience, we can actually get these down to around 25 amps.

So we’re gonna sit here and wait for a while, and see what it does. So we’ll come back in another 10 minutes and we’ll show you where it’s sitting then, and give you an actual run time, but already, we’re up to two hours, 24, where we were at an hour and a half before, just by going to 21 degrees.

After Another 10 Minutes

So interestingly enough, it’s been about 10 minutes and at the moment, the compressor’s actually cycled out.

We’re still sitting on 21 degrees, and would you believe we’re only pulling five amps. And it’s showing I got a 26-hour run time. Now, obviously this is gonna change, and it’s gonna cycle back in, but this just shows you the variance of temperature setting versus temperature of the day versus air conditioner.

So, we’re gonna give it another 10 minutes, and we’ll come back. Obviously, this compressor’s gonna cycle in, and it’s gonna pull more, but at the moment, we’re drawing five amps, van’s cool, and with three little AGMs, it’s telling me I got another 26 hours of this to go. That’s not real, but it shows you the variance in the system.

After Another 10 Minutes

So here we are again. Currently, it’s drawing, so it’s cycled back in, but I’ve got it sitting on 22 degrees now, and it’s currently drawing 15 amps, and we’ve got a run time of seven hours. 

So what I’m trying to show you is that depending on your expectations, running your air conditioning off-grid is achievable. The hard bit is understanding that running it in the morning is gonna be different to running in the afternoon. Running the heater in the morning’s gonna be different.

Your temperature settings gonna vary it greatly. So if you wanna do it, without spending a fortune on a big lithium setup, you need to manage it while it runs. If you’re managing it while it runs, you’re keeping an idea on how, keeping an eye on how much you’re discharging, and what it’s actually doing. You can easily achieve four, five, six hours run time out of an air conditioner. The one thing you need is the next day, the ability to charge it back up. So obviously, a large solar system is what it needs. This van runs autonomously. We’re sitting on about a kilowatt. 

I really hope this video has sort of explained the amp draw, battery size, solar conundrum that everybody wants, and maybe also help explain why there’s no just algorithm of how much solar versus how much battery versus what air conditioner works together because it really does depend on the person operating it, how long you’re gonna get out of it, and what you’re gonna achieve.

So if you’ve watched through all of this, congratulations. Any questions, feel free to give us a call, 1300 227 353 or email us at info@amae.net.au and I’d love to help.

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