I only have a converter on my 5er, so I can't operate any 120v items when I'm not connected to shore power. Found this out the hard way the other day. Pulled into the campground for our second ever campout with the 5er, and started our setup. I made sure the power at the post was off and plugged in my surge protector. Turned the power on and got all green lights. Cool. Turned the power back off and plugged the power cord into the 5er. Told the DW she was good to go on the inside and started setting up the rest of the outside items. Next thing I know she's yelling at me that the AC isn't working. I run into the 92 degree 5er and start pushing buttons. The thermostat is on, but the AC won't come on. So I'm standing there starting to drip sweat, steadily getting tee'd off because the fridge already doesn't work, and now I'm going to have to get the ACs checked. And then it dawned on me. Duh, you didn't turn the power back on at the post when you connected the power cord. Don't I feel like an idiot.So that leads me to my question. We're planning a long trip next year and I'm already planning an overnight in a Flying J enroute to our destination. I know I'll have to get an inverter IOT operate any 120v items without shore power. But how do I figure out how many batteries I'll need? Surely our one 12v battery won't last a night of AC and TV watching?

You cannot carry nor afford enough batteries to run an AC unit. 15 amps @120VAC amounts to 150 amps @12VDC. You really need a generator to power high current draw items like the AC for more than two or three minutes

One battery and one 3000+ watt generator.

Don't even think you can run an AC with an inverter. I have two 6V glass mat batteries which will last the night just fine running the furnace once in a while. But for the AC, you really need a decent generator. Depending on your AC, you might be able to get away with 2000 watts, but more likely will need at least 3,000 or more.

smkettner wrote:One battery and one 3000+ watt generator.X2

Hi,It is safer and probably cheaper to go to an inexpensive campground if you need the air conditioner.If you wish to run the air conditioner it would require a large pure sine wave inverter (at least 2000 watts). It would also require a considerably larger battery bank than what is usual. It is possible to do so--but then the next day there must be a way to recharge the battery bank.So, yes, you can run the air from a large enough battery bank--but it is not practical to do so.

How many batteries for an overnight? | Good Sam Community

12 Replies

doughere
Explorer
Sep 14, 2014
2 batteries (6's or 12's) with about 200 AH capacity will give you 1 to 2 days of TV (150 watt PSW inverter will do fine), lights(convert lights to LED), water pump, Reefer on propane, and some heater usage. No A/C, no microwave, no coffee maker.

Anything past that will require a 2 to 3 KW generator and/or way more batteries than you can imagine and a big expensive PSW inverter for the microwave.

Doug
Vet_Man
Explorer
Sep 14, 2014
My friend who is an Electronics wize, set up his basement in his 38 ft MH full of golf cart batteries. I do not know how many he had. He had the big converter to run the A/c for 8 hrs. He needed it for medical reasons. He did the whole set-up himself, have no idea the cost. I know when we traveled together he had a small toad, and really slowed on the hills. He had the Work Horse chassis.
ken_white
Explorer
Sep 14, 2014
Couple of good suggestions -> carry a 3kW generator or camp where an AC voltage pedestal is present.

Ability to run A/C for 10-12 hours off battery and inverter power requires a very big and costly system...
RJsfishin
Explorer
Sep 14, 2014
Overnite w/ a little sat tv, 1 battery
Overnite w/ sat tv and very much furnace 2 batteries
All w/ a 3 - 400 watt inverter.

Overnite adding microwave use for even a few minutes, add another battery and bigger 1500 watt inverter.

Overnite w/ all the above plus A/C,.........you don't want to do it !:)
MEXICOWANDERER
Explorer
Sep 13, 2014
I sorta went by this hint...

"The thermostat is on, but the AC won't come on. So I'm standing there starting to drip sweat
MrWizard
Moderator
Sep 13, 2014
DO YOU MEAN 120VAC or do you mean A/C air conditioning

forget running A/C from battery power
you would need to fill the tow vehicle with batteries to run A/C from inverter
then you would need a way to recharge them

you need a generator to power Air Conditioning
MEXICOWANDERER
Explorer
Sep 13, 2014
For laughs I did the workup on a Vogue motorhome in the late 80's.

Twenty two 8-D batteries.
pianotuna
Nomad III
Sep 13, 2014
Hi,

It is safer and probably cheaper to go to an inexpensive campground if you need the air conditioner.

If you wish to run the air conditioner it would require a large pure sine wave inverter (at least 2000 watts). It would also require a considerably larger battery bank than what is usual. It is possible to do so--but then the next day there must be a way to recharge the battery bank.

So, yes, you can run the air from a large enough battery bank--but it is not practical to do so.
mena661
Explorer
Sep 13, 2014
smkettner wrote:
One battery and one 3000+ watt generator.
X2
TucsonJim
Explorer II
Sep 13, 2014
Don't even think you can run an AC with an inverter. I have two 6V glass mat batteries which will last the night just fine running the furnace once in a while. But for the AC, you really need a decent generator. Depending on your AC, you might be able to get away with 2000 watts, but more likely will need at least 3,000 or more.