Air conditioning and batteries

StevenG · 07-09-2009, 04:14 PM

We are planning our second trip in our new (to us) 1987 32' Excella. We're staying a week with electrical and water hookups in a state park, but to and from is another problem.

Will the a/c run off the batteries, and if so, for how long?
Also, I have severe sleep apnea, and need to run my CPAP all night long. Will the batteries do both?

Thanks!
Steven

purman · 07-09-2009, 04:18 PM

NO, you will need a 3000 watt generator to run the ac. The cpap I not sure about. You will need an inverter to change from 12 volt to 110. then you could try it out during the day and see how long it lasts.

wkerfoot · 07-09-2009, 04:20 PM

Steven,

Check with your CPAP supplier and obtain for a 12V DC adapter. That way you won't need an inverter.

Bill

StevenG · 07-09-2009, 04:23 PM

My electrical knowledge is not good. I'm assuming (and you know what assumptions do!

) that there is an inverter in the AS so one can plug an appliance into any outlet and it will work when "boondocking" i.e. using the batteries instead of being plugged in to a power source. Or am I wrong here?
Thanks,
Steven

bob34787 · 07-09-2009, 05:14 PM

first, no you cannot run ac from batteries. as far as running appliances, you can run as much as your inverter will let you. On my safari I can run lights and radio but not refrig or tv.

purman · 07-09-2009, 05:38 PM

Thats all I can run on mine. It will not invert it to the 110 plugs.

StevenG · 07-09-2009, 10:20 PM

hmmm I wonder if the owner's manual for the 1987 models will tell if it will run the outlets? or should I simply assume, as it won't on yours, it won't on mine. sigh... I guess if I decide to boondock, I'll need a generator for my cpap... blast... life was so much simpler before I went to the dr. last month.

but then again, maybe now it will be longer!

loudruff · 07-09-2009, 10:34 PM

I have a CPAP. Got the adapter so that it runs on 12v. I have run it 3-4 nights without a problem with the batteries. However, we were NOT running much else....no waterpump, only a few lights....boondocking in the driveway to give it a try.

Lou

Maryw164 · 07-10-2009, 01:39 AM

Regarding your CPAP: it is basically a fan. Look onyour literature that came with the CPAP and find out how many watts the unit requires. Then go to Walmart, Costco or like store and buy a 12v power inverter that will handle the wattage. We bought one at Walmart that our son uses in the car when traveling to power his PSP, laptop, etc.

Now the A/C can in no way ever be powered by your batteries.

Hope this helps.

Mary

brotherjethr · 07-10-2009, 09:01 AM

Another way to put it: Assume for a moment that you -could- run the AC from your batteries. How long would it last? Well, let's do some simple best-case math: The batteries have no more than 50 amp hour capacity, so 12 volts * 50 amps * 1 hour * 2 batteries = 1200 watt hours. My AC runs at < 15 amps, so let's say it takes 120 volts * 14 amps = 1680 watts. 1200 watt hours / 1680 watts = 0.71 hours, or 43 minutes. And that's assuming 100% efficiency, ignoring the effects of such high current drain on battery capacity & life, and killing your batteries by discharging to 0%. A more realistic number is half, or 20 minutes.

So in other words, it wouldn't be worth the trouble.

StevenG · 07-10-2009, 09:31 AM

Thanks all! You've been a great help, and I appreciate it.
Steven

tpi · 07-10-2009, 09:57 AM

If you had 10-20 RV batteries (or equivalent capacity), the air conditioner would be viable.

This weight limits mobile use almost to the point of non existence-at least for travel trailers.

It would be interesting off grid combined with adequate solar capacity-such as a remote private campsite.