Running A/C off new large lithium battery

[Ken_Judy]

Hi guys, the 4 AGM’s on my 2018 Oliver are kaput. I am installing a new Vatrer 460ah and was wondering how hard it would be to run the A/C off of it. I know I would need a 3000 watt inverter. Would I just take the A/C wires off the charger/converter and make a plug that plugs into the new inverter?  Thanks

[Ronbrink]

You will need to install a dedicated automatic transfer switch to be able to run the a/c off the batteries via the inverter and still be able to operate it when on shore power. No need to upgrade the inverter just to be able to run the unit in this manner. You will also need to install a shunt and fuse with the battery upgrade. Search ‘Ollie Modifications’ for owner write ups to glean information and install details.  Here are a few pics on the required ATS to get you started:

My install.

Pic provided by another illustrating the wiring.

ATS wiring diagram.

Edited Saturday at 01:56 PM by Ronbrink

[jd1923]

On 10/2/2026 at 3:00 PM, Ken_Judy said:

Hi guys, the 4 AGM’s on my 2018 Oliver are kaput. I am installing a new Vatrer 460ah and was wondering how hard it would be to run the A/C off of it. I know I would need a 3000 watt inverter. Would I just take the A/C wires off the charger/converter and make a plug that plugs into the new inverter?  Thanks

These Vatrer batteries should be a good choice, great $/Ah cost! I was hoping to see somebody go this direction.

You should know only one (1) of these will fit in the battery bay, so no room for future expansion with one 460. You could install 2-3 of their 300 Ah batteries instead, for more money of course. Either way, none of the Vatrer choices fit in the MORryde battery tray except for one 300.

Running A/C? Ron is correct in that adding the 20A ATS, RV A/C can be run on a 2KW inverter. He has his working well, I tried it and then upgraded to the Victron 3K inverter. There are other considerations. 

I'm thinking since you currently have AGM batteries, maybe you have the Dometic Penguin II A/C?! If so, this beast of old pulls 150A when running, which means that for every hour you run it you're using 150 Ah of your LiFePO4 batteries. On a 460 AH battery running the old P2 will reduce SOC by 30% every hour, just 3 hours to a dead battery.

First you want more Ahs if you truly want to run A/C via the inverter! Many Oliver owners have installed better A/C units; the Truma, Dometic Freshjet, Houghton and Tosot. They are about 40% more efficient, so instead of 3 hours, 460 Ah should last 5 hours. These A/C models all have single-speed ON-OFF compressors, that run ON most of the day when hot out.

If you install an inverter-compressor A/C like Turbro, Pioneer, etc. or the variable-speed Chill Cube these numbers improve greatly. We have 900 Ah and the Furrion Chill Cube A/C. I had no idea the numbers would be so good. I ran several tests and on average we used 200 Ah to run this A/C for 24 hours, on a sunny day in AZ with a high of 93F. The 320W rooftop solar was also adding power which likely added another 120 Ah/day +/-. But I ran our Chill Cube A/C all day on battery for what the Dometic P2 would have consumed in 90 minutes! I ran tests for two weeks at home and since have used the new A/C about 8 days on 2 camping trips.

To run A/C regularly on inverted power you need enough Ahs, say 600 min, 900 Ah better! You need an efficient A/C unit, otherwise the idea is not viable. For occasional use, upgrade per Ron's suggestion. Want to do this regularly, upgrade your inverter to a 3KW model.

I had no idea it could work this way when I started. Yeah, it's a can of worms where one upgrade may lead to the next.

Edited yesterday at 06:05 AM by jd1923

[dewdev]

@Ken_Judy

I had my 2018 hull #354 Elite II last fall upgraded with lithion batteries. The existing 4 AGM batteries were removed and the old Xantrex 2000 inverter was removed, since it did not have a switch to allow lithion batteries. Four 130 ah Lithionic batteries and a Xantrex Freedom XC 3000 Pro Inverter-charger was installed. The battery wiring did not need to be replaced as they were the correct size. The existing charger was left in place but the charger wires were removed and its existing AC and DC breakers-fuses are still utilized. No other hardwear was required to be installed. 

I can run the Dometic AC (with it soft starter) utilizing the inverter in the on position. If fact, I use the AC to bring the batteries down do 50% prior to removing them for the witner months. This takes about 2 hours + to get from 100% to 50%. To run the AC for longer time periods would require either more ah battery capacity or a standby generator to charge the batteries or connected to AC to charge the batteries.

Edited yesterday at 04:27 PM by dewdev

[jd1923]

2 hours ago, dewdev said:

I can run the Dometic AC (with it soft starter) utilizing the inverter in the on position. If fact, I use the AC to bring the batteries down do 50% prior to removing them for the winter months. This takes about 2 hours + to get from 100% to 50%.

Richard's experience and data runs pretty much in line with mine. He has 520 Ahs and running the Dometic P2 for 2 hours uses 50% or 260 Ah which comes to 130 Ah per hour. I measured a constant -150A draw in the heat of the summer. Richard is doing this in the fall which is much less hot out, so the compressor is cycling some using 15% less power (150A/130A = 1.15). So yes, you can run A/C, but with any standard (on-off) compressor A/C, it would be for a very short period of time.

Another item to notice is the soft-start requirement. Variable speed A/C does not need Soft-Start since they start soft by design, can run easily on the 2KW inverter or generator too.

Any A/C can run on a 3KW inverter, but to truly have air-conditioning, the system has to be able to cool the cabin for the period of time for your comfort. Several times, we just want to cool the cabin for a few hours in the afternoon, after being out for the day, coming home to a hot cabin at 3 PM. I turn it on "Turbo" for about 20 minutes, then to Cool-Auto Fan. The fan drops down in speed and gets quiet. After 7 PM it cools down outside and we open the windows later. I have found with the Chill Cube variable-speed A/C we can do daily and our SOC drops by only 10% (90 Ah). And the next sunny day our solar can recharge that 10% loss, or the next time we're towing the Dc-DC charger will restore SOC%. With the 3KW inverter, we can also run anything else electric (e.g. the Air Fryer) while running the A/C.

So @Ken_Judy you need to upgrade from AGM to Lithium. Wanting A/C is more about upgrading your A/C vs. your inverter. To reach your goal of having A/C when unplugged, to do it right you want all the Ah possible, the variable speed A/C and the 3KW inverter.

[FloraFauna]

18 hours ago, jd1923 said:

To run A/C regularly on inverted power you need enough Ahs, say 600 min, 900 Ah better!

I agree but would double jd's numbers.  We have 640 Ah Lithionics.  I feel i have maybe 5 hours of ac, maybe a bit more but unless you have the capability to recharge, you wont have sufficient power for the rest of your trip.  400 watts of solar probably will take a very, very long time to recharge given your power draw for lights, fridge, etc.  I have the truma aventa ac.  

 

Edited yesterday at 06:37 PM by FloraFauna
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