Running AC while towing

Spectre9

Has anyone else enabled running AC prior to parking to cool down trailer on a 5000 BTU AC unit like a 2018 320s?  Am ready to have trailer not be in triple digits at bedtime when we are driving late and ready to crash.

I have a 20A onboard charger and a 105ah lithium and the inverter does the job.  Am considering taking our solar from 150 to 350 watts as our wiring is 10awg fused at 30a

I’m thinking there was someone maybe who did this with a 120v cable from the TV even.

Dutch061

With the intake and discharge on the side of the camper, I am not sure how well it would actually work. You could always give it a try to see what happens.

Chances are that the 30 Amp charge rate will not be near enough to compensate for the 120 VAC draw. Example, if the A/C only draws 10 amps (120 VAC x 10 Amps =1200 Watts) , that becomes 100 amps from the battery (1200 Watts divided by 12 volts = 100 Amps) (not counting efficiency loss). Simply means that if these were the numbers, you would be out of battery in a little over an hour.

Brad

Spectre9

My net charge rate will be 20A/250watts from the TV plus the 350 watt solar.  I’m willing to accept some battery drain too as would happens if it’s dark out.  The goal here is not run run AC overnight but rather just not have a trailer with a super hot interior and bed when time to sleep for night.  Another 4000 mile trip in August ahead for us

jkjenn

IMHO, it isnt worth the massive amount of power that would be used. Between your inverter and the AC, I would bet a draw of around 15ah. I have found that once the sun goes down, the Aac really cools things down much faster as it no longer is fighting direct sunlight. After four hours of running the AC, you would only have 40% of your battery left.

An alternative is to get a max air fan and exhaust the heat while you drive. It does a pretty nice job moving air at a fraction of the power use.

falcon1970

I usually pull into a campsite, chock the wheels, connect to shore power and then turn the AC on.  By the time I have unhooked and gotten everything set up the TAB 400 is well cooled down.  Don't forget to close the door though!

rfuss928

jkjenn said:

IMHO, it isnt worth the massive amount of power that would be used. Between your inverter and the AC, I would bet a draw of around 15ah. I have found that once the sun goes down, the Aac really cools things down much faster as it no longer is fighting direct sunlight. After four hours of running the AC, you would only have 40% of your battery left.

jkjenn
I'm not sure how your calculating the power usage but, as Dutch061 described in the first comment, the battery would be completely depleted in less than an hour.
A 5000btu air conditioner will require at least 1500watts.  The 105AH (1260watt-hours) battery will be completely depleted in ~45 minutes (~20 min to 50%).  Even the overly optimistic charging rates Spectre9 states would make very little difference in the ability of his battery and charging system to run his AC.

Dutch061

@rfuss928, exactly and I didn't add in the additional 10% for the efficiency loss which just pushes it further beyond practical. I had thought about upgrading my inverter now that I have 2 x BB but it just doesn't play out well. I always carry a 3500 Watt generator anyway, so if I needed to run my AC while boondocking or top off the batteries it is simple to do

Brad

DougH

@Spectre9 I used to have 300W of solar, 375Ah battery, and a 6000-6500BTU A/C on the T@B I sold this year. The A/C only averaged 400-500W when compressor was on, so with enough juice from solar, battery bank, and tow vehicle, power would NOT be a problem with leaving the A/C on while towing.  That's if you have the 320.

However, many air conditioners not specifically designed for a moving vehicle could have failures if operated while on the road.  It would be an interesting experiment, but might cost you $200-300 to find out the A/C you have doesn't like running the compressor under way.

And more importantly, the T@B is not a hermetically sealed canister.  Especially when traveling there's a lot of exchange of air with the outside.  So I don't think you'd arrive at the destination with a significantly cooler T@B than ambient.

As jkjenn suggests, just having a cover over your top vent and leaving the vent open will suck the heat out of the camper while moving... no need to even run the fan. Then the moment you arrive, turn on the inverter or shore power and turn on the A/C before leveling, setting up water, etc. and the camper won't be too bad within a half hour.

But it would be interesting to run the experiment anyway, just to see how many degrees below ambient you could achieve on the highway.