What's needed to run AC without generator?

[djronh1]

Hi All,

We got our 2022 21C last June.

We ordered it w/ the Coleman 13,500 AC, solar package w/ two 190 watt solar panels, exterior solar plug/connector, 1500 watt inverter, and lithium ready package.

Only upgrade we've done is replaced the battery (that was included with the lithium ready package) with a 12V 206A SOK.

Watched a bunch of YouTube (Will Prowse, etc) and try to determine what would be required to use our AC without a generator (some sites we're interested in don't allow them).

Had considered a Ecoflow Delta Pro but that seems kinda pricey since would need additional battery(ies) to be able to power AC for several hours. (BTW - Here in the US, we'd be able to claim the 30% tax rebate since it's over 3K. Even with rebate still too expensive for amount of use anticipated).

Not looking to spend crazy $$$, or anything like the Johnny Hung mod.

Thanks

[brroberts]

ALOT more battery, and a lot more solar to charge it.

A/C takes a lot of electricity. You need shore power or a generator unless you want to spend a lot of money on batteries and solar. You might also consider a more efficient A/C like a mini split or at least a Houghton 9500. This all takes a lot of power and money.

It’s why most of us use hookups or generator for A/C. We tend to travel when it’s cooler, and look for higher elevation and go north when it’s hot. We have also used the MaxxAir fan, and have fans permanently installed in the dinette and bed. Try to cook outside when it’s hot. The propane cooktop really heats up the inside. Also use the awning and shades to keep the trailer as cool as you can.

[Centex]

Originally Posted by djronh1

... Not looking to spend crazy $$$ ....

What's your dollar limit for 'not crazy money'?

[djronh1]

Thanks for the info.

With my exterior solar port/connector, adding some additional panels (when needed) shouldn't be too bad.

BTW - Just found this 4096Wh LiFePO4 alternative to Ecoflow Delta Pro

Prime Day has it down to $2,400 .... but not sure if it's eligible for the 30% federal rebate.

If it is eligible, then final cost would only be $1,680. Which seems like a great price.

[djronh1]

Originally Posted by Centex

What's your dollar limit for 'not crazy money'?

Under 2K would be ideal

[TTMartin]

Originally Posted by djronh1

Thanks for the info.

With my exterior solar port/connector, adding some additional panels (when needed) shouldn't be too bad.

BTW - Just found this 4096Wh LiFePO4 alternative to Ecoflow Delta Pro

Prime Day has it down to $2,400 .... but not sure if it's eligible for the 30% federal rebate.

If it is eligible, then final cost would only be $1,680. Which seems like a great price.

You have to understand the difference between Watt Hours that portable power units are rated in, and Amp Hours that batteries are rated in.

Volts X Amps = Watts

So a 4096 Watt Hours would be 341 Amp Hours. Compare that to the cost of buying additional SOK batteries.

The Specifications of the 13,500 btu Mach 10 are:
BTUs: 13,500
Volt rating: 115VAC, 60Hz, 1 Phase
Full-Load Cooling Amps: 13.6
Standard Running Watts: 1350
Weight: 80Lbs
Height: Mid (11.8")

Using the specified 'Standard Running Watts' of 1350

4096 Watt Hours / 1350 Watts = 3 Hours

So you can expect the 4096 Watt Hour Ecoflow Delta Pro to be able to run the Air Conditioner Compressor for about 3 hours before needing to recharge the unit.

[Escape_19]

To run the AC with no generator you will need AC ...probably 30amp...just guessing though

[Ooshkaboo]

Originally Posted by djronh1

Hi All,

We got our 2022 21C last June.

We ordered it w/ the Coleman 13,500 AC, solar package w/ two 190 watt solar panels, exterior solar plug/connector, 1500 watt inverter, and lithium ready package.

Only upgrade we've done is replaced the battery (that was included with the lithium ready package) with a 12V 206A SOK.

Watched a bunch of YouTube (Will Prowse, etc) and try to determine what would be required to use our AC without a generator (some sites we're interested in don't allow them).

Had considered a Ecoflow Delta Pro but that seems kinda pricey since would need additional battery(ies) to be able to power AC for several hours. (BTW - Here in the US, we'd be able to claim the 30% tax rebate since it's over 3K. Even with rebate still too expensive for amount of use anticipated).

Not looking to spend crazy $$$, or anything like the Johnny Hung mod.

Thanks

Search for a Bob G post on this. I have the same AC and it can really take the edge off. I was as you and I had pretty much given up until I read a post on which Bob mentioned his.

[rubicon327]

Originally Posted by djronh1

Under 2K would be ideal

Sorry to be blunt it is not possible to accomplish appreciable runtime off battery for a 13,500 BTU A/C for that amount of money.

[rubicon327]

Originally Posted by Ooshkaboo

Search for a Bob G post on this. I have the same AC and it can really take the edge off. I was as you and I had pretty much given up until I read a post on which Bob mentioned his.

Bob describes his system here. Between his solar, Victron MultiPlus inverter/charger and batteries he is WAY over $2K.
https://www.escapeforum.org/forums/f...tml#post406433

[hugh]

FWIW, I built a 960ah battery bank that I use to run my AC. The cost of the batteries was around $2k, but you'll almost certainly need to upgrade your inverter and wiring.

More info here:

https://www.escapeforum.org/forums/f...tes-23522.html

[hugh]

BTW, one thing we've really enjoyed about battery powered AC is being able to pull into a rest area for a break, and have a nice cool lunch or dinner inside the trailer. Might sound silly, but in the southeast it gets very hot and humid in the summer!

[rubicon327]

There are very costly systems like Johnny Hung's with enough battery and solar to run 24/7/365 and then there are more basic systems that are less costly but still meet the needs of the user. I have not built out a solar system yet but added a 400AH Bestgo lithium battery and 2000W Xantrex Freedom XC inverter/charger. This was primarily done to increase the time between charging and be able to use the microwave when the trailer is used for a month off-grid as a fishing basecamp. Since I already had a 9,000 BTU mini-split it was easy to wire the system to run the A/C. Based on my system tests it can run for 6 hours +/- in full heat/sun before the battery is at 20% or it can run completely through the night and only bring the battery down ~25%. The second part is key. Nothing like having whisper quiet A/C (both inside and outside the trailer) to run on a hot, humid night in a campground without services. Didn't even disturb the kids that were in the tent 15 feet away. If the site allows I can recharge the battery during the day for a few hours (the Xantrex can provide up to 80A charging) using a Honda EU2000 generator with DIY rigid foam enclosure so it can hardly be heard. Since we are out of the trailer most of the day I really want the A/C for at night. If you are at a site that does not allow generators than this obviously becomes a lot more difficult as the solar required is extensive. My battery, wiring, inverter/charger and misc parts were still probably about $4K. This does not include the mini-split, solar or any labor.

[brjohnso]

Air conditioning is a huge power hog (at least the 13,500 unit you and I have). In fact, it uses more energy than everything else combined. Even running it for just a few hours will require a very large inverter, and a huge battery pack that will cost thousands of dollars. Just off the top of my head, to run about 4 hours, you would probably want a good 3,000 watt+ inverter (about $1000), and about 5 or 6 100ah lithium batteries ($2500-$3000). The wires, fuses, breakers, and transfer switch are going to add some $$ too. Add to that the solar to charge it each day too.

If I was going to do it, I would start by replacing my 120v AC with a smaller DC high-efficiency AC unit, then go from there. I would also look at residential mini-splits. Typical RV air conditioners are crazy inefficient, and given the very high cost of solar/battery power, you need to minimize the load first.

[brjohnso]

Here's some more information on 12v AC units. The Marbu 12v DC air conditioner draws about 55 amps on high (about 660watts), and provides 11,000 btu. The coleman mach 13500btu draws 1500 watts, over twice what the Marbu draws. In addition eliminates the "hard start" issue and the noisy clunking off and on of a traditional AC unit because it has a variable speed compressor.

Once you have changed out the old AC for this more efficient DC-powered unit, you would no longer need to upgrade your inverter, and you could just run the air conditioner like any other DC load in the trailer. With say, 400 amp hours of lithium batteries, you could easily run your air conditioner for 6-8 hours. You would also need a lot less solar because you wouldn't be wasting so much on an inefficient air conditioner.

[CE Vogel]

You will not be able to run AC on batteries for any reasonable length of time for under $2,000. Air conditioners are too much of a power hog. Here is some math explaining why.
Discharge
An AC draws about 14 amps at 120 volts. Doing the math, that’s about 1680 watt-hours of power per hour of use (assuming it runs continuously).
14A x 120V = 1680 Wh per hour
If the AC runs for six hours on a hot day, about 10,000 watt-hours of battery storage is needed.
1680 Wh x 6 hours = 10,080 Wh storage
Assuming typical lithium batteries with about 1100 watt-hours of storage each, you need 10 batteries to provide 10,080 watt-hours of energy. However, to preserve battery life and leave energy for other items like lights and water pump, it is better to assume 80% discharge, which then requires 12 batteries.
1100 Wh per battery = 9.2 batteries @ 100% discharge
1100 Wh per battery = 11.5 batteries @ 80% discharge
Charge
The above calculations get you one day of operating the AC. Now you need to recharge the batteries. Let’s start with solar. Typically on a sunny day you can average about 5 hours of full charge rate. We need to recharge 10080 watt- hours in 5 hours. This requires just over 2000 watts of solar, assuming a perfect system Assuming a more typical system efficiency of 80% (charge controller losses, inverter losses, battery inefficiency, etc.), you now need 2520 watts of solar panels.
10080 Wh ÷ 5 hours = 2016 W solar @ 100% efficiency
10080 Wh ÷ (5x.8) hours = 2520 W solar @ 80% efficiency
Now lets assume charging from the tow vehicle. Using the charge line through the 7-pin connector, the best you can get is 30 amps, more typically 20 to 25 amps. Assuming Lithium batteries requiring 14V charge, we need 720 amp-hours to recharge the batteries.
10080 Wh ÷ 14V = 720 Ah.
At a 30 amp charge rate we need 24 hours to recharge the batteries. At a more realistic 20 amp charge rate, we need 36 hours.
720 Ah ÷ 30A = 24 hours
720 Ah ÷ 20A = 36 hours
To make all this work, you need to install a large solar charge controller, at least a 3000 watt inverter, a soft start in your AC unit, and massive wiring, fuses, and circuit breakers. All these items generate heat, so cooling will need to be considered during component installation.
If running an AC on solar was easy, many RVs would offer it as an option. The above math shows this is NOT easy, though it is possible. A generator is much more cost effective.
If you really want to run AC on solar, you need to replace the AC unit with a smaller, more efficient unit. Search this forum for mini-split system installations, or you may consider installing a DC air conditioner. Both these alternatives still require all the above calculations, though the number of batteries and solar panels required will be reduced.

[hugh]

A lot of the calculations here are probably a bit pessimistic on the real-world energy consumption of an AC unit. Our Coleman Mach 10 (13.5k btu) draws 1200-1300 watts with the compressor and blower running, and around 200 watts with just the blower. In my experience, the compressor doesn't run anywhere near 100% of the time, so I've been able to get 18-24 hours of runtime on a charge without much difficulty.


It's certainly true that AC does use a lot of energy, but that doesn't mean it's not possible (or practical) to build a battery system to run it. Personally, I find the ability to run the AC on batteries very useful.

[oldwave]

A 3000 watt pure sine inverter and 3 or 4 batteries with 100 amp hour bms in parallel
Or a victron 350 ah smart battery that out puts 600 ah continuous

A decent inverter generator is more cost effective

[Civilguy]

We use a 12V marine fan. They're quiet and the power draw is fairly low, particularly if you have more storage capacity than the standard pair of 6V lead-acid batteries.

Our Hella can even be set to oscillate and it looks like you can still buy one for well under $100. But then, we also try to follow the weather and/or camp with shore power.

Hopefully the forum judges will allow this answer as a sometimes-viable alternative for partial credit.

[Mike Lewis]

Earlier this year I met a couple who were fulltiming in a large fifth-wheel RV. They had 2,000W of solar on the roof and six BattleBorn batteries, i.e. 600 A-h. They told me they could run their rooftop A/C for three hours with this setup, enough to cool things down for the evening.