Unusual Mix Of AC Power

[Chance]

Unusual mix of air conditioner power type/source has been discussed before, but this is first I have seen on a factory RV. On RVs with dual air conditioners that are set up with significant lithium battery capacity to power air conditioner overnight (for sleeping when off the grid), why not a 12 VDC unit in bedroom area? It’s unusual in that main living area air conditioner remains 120 VAC.

Obviously there are design issues to deal with, but those who want to air condition at night without having to run generator, this approach may make technical sense.

It appears Jayco is using on large trailers, but same approach should work on motorhomes. I’m referring to the Overlander Premium EXT Package option.

https://rvbusiness.com/jayco-launche...power-systems/

[DavidEM]

With enough lithium batteries, you can power anything. The trick is recharging them. There are several choices:

A big, like 1,000 watt solar panel array.

A robust chassis alternator with appropriately sized DC to DC charger.

Run your generator.

David

David

[RACarvalho]

Originally Posted by DavidEM

With enough lithium batteries, you can power anything. The trick is recharging them. There are several choices:

A big, like 1,000 watt solar panel array.

A robust chassis alternator with appropriately sized DC to DC charger.

Run your generator.

David

David

Can you post the calculation why do you think a 1000W solar array can power AC for any significant amount of time?
At a realistic 50% efficiency a 1000W solar array will produce 42Ah considering a 5h/day that is only 210Ah / day...
A low power AC should use 100ah / hour (from the 12V battery) so an entire production day of that solar array can only power a small AC for 2 hours (best case scenario).....
(all ah calculated @ 12v for comparison simplification)....

[Chance]

Originally Posted by DavidEM

With enough lithium batteries, you can power anything. The trick is recharging them. There are several choices:

A big, like 1,000 watt solar panel array.

A robust chassis alternator with appropriately sized DC to DC charger.

Run your generator.

David

David

As a trailer application it is unlikely to have high-amperage alternator charging capability, but specs show a generator option. Generator plus high-capacity inverter/charger should recharge the 6 lithium batteries in reasonable period.

From specs, it appears the main charging source is intended to be the 1,200 Watts of solar. On a sunny day that could produce up to 5 kWh of electricity, which matches well with +/- 7.5 kWh of maximum lithium battery storage.

For active campers who are out and about during day (hiking, cycling, fishing, swimming, touring, etc.) and mostly need air conditioning at night to sleep comfortably, an efficient 12 VDC air conditioner should run all night (if only cooling bedroom). Even more likely scenario might be to use system while driving long trips and stopping to sleep — batteries would charge during day with solar while driving and then power AC through boondocking night.

Copy of specs below.

The complete Overlander EXT package includes:
6-200W Solar Panels
6-100AH Lithium self-heated batteries
100AMP MPPT Solar Controller
3000w Split phase Inverter Charger
DC/DC Power Charger
Soft Start Power Saver in living room 15K AC with heat pump
12-volt 13.5K bedroom AC
Battery Monitor
Energy Management System
Generator option capable
Heavy gauge steel battery Enclosure

[Chance]

Originally Posted by RACarvalho

Can you post the calculation why do you think a 1000W solar array can power AC for any significant amount of time?
At a realistic 50% efficiency a 1000W solar array will produce 42Ah considering a 5h/day that is only 210Ah / day...
A low power AC should use 100ah / hour (from the 12V battery) so an entire production day of that solar array can only power a small AC for 2 hours (best case scenario).....
(all ah calculated @ 12v for comparison simplification)....

Your numbers are way off. System has 1,200 Watts solar, and 12 VDC A/C doesn’t require 100 Amps. Plus at night, air conditioners don’t run nearly as loaded.

[RACarvalho]

Originally Posted by Chance

Your numbers are way off. System has 1,200 Watts solar, and 12 VDC A/C doesn’t require 100 Amps. Plus at night, air conditioners don’t run nearly as loaded.

Doesn't matter what voltage you have, a 1200W air conditioner will require 1200W to run .
in a 120V AC system that is only a 10A draw (from pedestal or genny) but it is 100A draw from a 12V power source (Li batteries)....
So I stand correct that, if you are running the AC from the batteries and expect the 1000W solar array to help you, that (expensive) solar array will only give you a 2h extension to your battery banks on a best case scenario.
2h of AC is basically nothing in term of AC run if you have anything beyond 80F on the outside....
My point is : A small AC will require 100A from a 12V system and that will deplete the Li batteries really fast even if you have a 1000w (expensive) solar array system.

[DavidEM]

A 13,500 btu A/C is much too big to run efficiently cooling a bedroom at night. I have seen 5,000 btu 12V DC A/Cs that should work much better.

David

[Chance]

Originally Posted by RACarvalho

Doesn't matter what voltage you have, a 1200W air conditioner will require 1200W to run .
in a 120V AC system that is only a 10A draw (from pedestal or genny) but it is 100A draw from a 12V power source (Li batteries)....
So I stand correct that, if you are running the AC from the batteries and expect the 1000W solar array to help you, that (expensive) solar array will only give you a 2h extension to your battery banks on a best case scenario.
2h of AC is basically nothing in term of AC run if you have anything beyond 80F on the outside....
My point is : A small AC will require 100A from a 12V system and that will deplete the Li batteries really fast even if you have a 1000w (expensive) solar array system.

Sorry to have been too brief — was rushing on way to early voting.

My assumption is that since 12 VDC air conditioner is installed in bedroom, that the primary intent is for it to be used at night. Additionally, a high-efficiency AC does not need 1,200 Watts of power to cool a bedroom at night. A DC unit can run steady at slower speed and save significant power. I posted information on direct-current Coleman AC in a different thread (again, I’m assuming that since Thor owns both companies, they would use Coleman on Jayco rigs). However, we do need updated information on lower voltage 12 VDC. If I recall, specs I found previously was for 48 VDC Coleman air conditioners.

Solar production can be all over the place depending on conditions — from nothing to quite a bit. For typical summer conditions in southern areas requiring air conditioning the most, the 1,200 Watts of solar panels should make “about” 3,600 Watt-hours daily (about 300 Amp-hours on 12-Volt system). For estimating purposes, typical energy on clear day is about 3 hours worth of panel rating. Please understand it will never make 1,200 Watts, but “on average” during 8~10 hours of sun, it will add up to about 3 hours worth of full panel rating.

Based on system specs, I can’t imagine engineers expect either air conditioner to run directly from solar during the day on an ongoing basis. If buyers expect that, they will be disappointed.

[RACarvalho]

Originally Posted by Chance

... If buyers expect that, they will be disappointed.

Tks for that explanation.
Generating false expectations on customers is my concern here.
Yes, down south you can get a better production from solar panels than what you get up north but then down south is also HOTTER and running ac only at night is really not the expectation there! (nor it is in Utah, etc) if you consider your insulation is only 1in, then the real life picture is really bad for a small AC running from batteries....

I use to have a 29Ft camper with only one 15K BTU AC and it never run only two hour during the the day and we like fresh air so we only turn it on when it is really needed.....

False expectations lead to frustrations that lead to business destruction.

[16ACE27]

Originally Posted by RACarvalho

Tks for that explanation.
Generating false expectations on customers is my concern here.
Yes, down south you can get a better production from solar panels than what you get up north but then down south is also HOTTER and running ac only at night is really not the expectation there! (nor it is in Utah, etc) if you consider your insulation is only 1in, then the real life picture is really bad for a small AC running from batteries....

I use to have a 29Ft camper with only one 15K BTU AC and it never run only two hour during the the day and we like fresh air so we only turn it on when it is really needed.....

False expectations lead to frustrations that lead to business destruction.

Not to mention that you have to have the RV parked in the sun to get that solar which means it will have heated everything in it to a higher temperature before you kick on the A/C which has to cool all the physical structure (not just the air) meaning it has to work harder to make it comfortable than if the RV had been in the shade all day.

[Chance]

Yeah, the most likely scenario for this type of system to work great is when pulling trailer cross country or long trip, where solar panels are out in sun. At night owner stops at rest area, W-M or Cracker Barrel and can quietly run bedroom air conditioner all night.

Another possibility is guy at races where he’s outside all day, and RV sits in full sun. At night a little air conditioning would be great.

Since we don’t have a built-in (Onan) generator, I can relate to what this system could do for us if designed right. When traveling through day, and boondocking in rest area or at football games, the ability to power small air conditioner at night (primarily to sleep) would be nice to have.

Daytime steady cooling using solar power is a different problem altogether. I’m aware of only one person who is doing it and he spent way too much in my opinion in order to avoid a generator. In case of Jayco option, I suppose much will depend on how high it is priced.

[Judge]

Here is a real world experience.....

Last year I did a LiFePO4 conversion and installed (5) 170AH batteries from BigBattery for 850Ah. This year I upgraded the stock Xantrex Freedom X 2000 to their Freedom XC Pro 3000 Inverter / Charger. I then rewired the coach so I could run any circuit from the Inverter.

Back in late August we boondocked at a Cracker Barrel in Illinois. I don't like to run the genny when others may there overnight as well. I used the Inverter to run one of the A/C's overnight (Coleman Mach 13,5K BTU). My wife also had her electric (AC) fan running and we were charging two laptops and two cell phones overnight. In addition I had the residential fridge and outdoor kitchen fridge running.

In the morning we made two pots of coffee. When all was said and I done, I was down to about 75% SOC.

Between 495W of solar on the roof and my dual alternators (175A each) with a LI-BIM 225, the batteries got charged back up to about 95% after 8 hours of driving during the day.

My setup works perfectly for my needs when I don't want to use the genny.

Now the F-550 A/C in my Magnitude is a beast and does a great job keeping the front half of the coach cool while driving. It was dark when we parked so the entire coach was cooling down by the time we stopped.

The other thing that was great about my setup.... when we were in Arizona with temps at 100+, I could run one A/C off my Inverter while driving with the alternators and solar helping to minimize battery drain and I didn't have to run the genny in high temps and burn more diesel.

My wife also loves that she can start cooking lunch in the Convection Oven before we stop to eat without having to fire up the genny.

[LarryD]

Judge, did you install soft starts on the a/c to make them work off inverter/battery? Any chance that our a/c has a soft start already installed?

[Judge]

Originally Posted by LarryD

Judge, did you install soft starts on the a/c to make them work off inverter/battery? Any chance that our a/c has a soft start already installed?

I have two of the typical Coleman Mach 13,500 BTU A/C units in my '20 Magnitude SV34.

The Xantrex Freedom XC Pro 3000 Inverter/Charger I upgraded to run the A/C without the SoftStart. No issues at all. The specs on the Freedom XC Pro are good enough to start and run one A/C.

Then I got a great deal late summer on a pair of SoftStarts and the only reason I installed them was in case I got into a situation where I needed to run both A/C's on 30Amps or I wanted to run then both on my 30A service at home. I did have a need for it one time and no issues running both A/C off 30A.