12volt AC unit

[Motrukdriver]

I was looking around for alternatives to 120 volt ac units and found this.  Anyone have any experience with them?  What kind of battery bank would you need to run it thru the night?  I'm guessing it starts and stops so the voltage draw wouldn't be constant.

http://www.cruisencomfortusa.com/

[sternwake]

I see one of the specs lists 30 to 46 amps.

A pair of GC-2 batteries has ~220 AH They earned that capacity rating powering a 11 amp load for 20 hours, before battery voltage hit 10.5v, which is considered 100% discharged.

Loads higher than 11 amps will reduce the total available capacity of this pair of batteries. due to peukert effect.

So a new Healthy fully charged pair of GC-2 batteries rated at 220Ah capacity with that 11 amp load, will have 156Ah of capacity with a likely generous peukert number of 1.1.

So at 30 amps it would take a total of 5.5 hours of run time of the AC unit to 100% discharge that pair of GC-2 batteries, assuming they were indeed fully charged and healthy, and the AC was the only load, and the cabling was thick enough to not heat up passing those 30 amps.

How much the AC would actually run is dependent on the ambient temperature and the desired temperature and how much heat is being produced by living humans within, who are trying to stay cool.

If someone wants to play with different capacity batteries and different size loads with a peukert calculator:

http://www.csgnetwork.com/batterylifecalc.html

Most batteries spec sheets do not list the Peukert number. Odyssey AGM lists a 1.112 on their group 31. A peukert number of 1.11, opposed to 1.1, reduces the total available battery capacity of those GC-2s by another 5AH

The numbers above assume a 1.1 peukert number. the higher the number the worse it performs capacity wise under loads higher than the load at which it earned its capacity rating.

100Ah battery can provide 5 amps for 20 hours, ect.

The peukert number is generally higher on batteries with thicker plates designed for deep cycle usage, and gets higher as they age.

[Scott7022]

I looked into these before I found the Canadain company that designed a different 12 system. They don't use Lithium batteries as they build a hanger to drop in a pair of group d8's to run the unit for 7 hours. Peukerts Law is a little different when using different chemistry. In this instal location, the batteries get too cold for Lithium.

I've researched this a bunch for my build and of all the 12 volt systems Cruise Air has the best rep. I know a few friends that use them in their boats. They can take a pounding. Not cheap and as Sternwake points out it will take a ton of juice to not deplete to past 50%