Dc Ac?

[Marlboro Mafia]

Anyone seen one of these? They claim it will operate on a 12 volt battery for 6 to 8 hours.

http://www.rdac.com/prod-cat-r6100.html

[nickcrowhurst]

The advertisement indicates that the air conditioner takes 33 amps at 13.6 volts DC. For 7 hours, that is 231 amp-hours. As a lead-acid deep cycle battery should ideally not be regularly discharged below 50 % capacity, that would require a battery of over 460 amp-hours capacity. I say "over", because batteries are rated for discarging over a 20 hour period. If discharged over a period of 7 hours, the capacity will be less, because of the extra heat energy released during a more rapid discharge. I seem to remember the standard Airstream group 27 batteries have about 90 amp-hours capacity. I'm no expert in these matters, but I'm quoting from what appear to be authoritative sources. The advert indicates this air conditioner is for commercial trucks, so perhaps such trucks have batteries with such a high capacity. Or perhaps I'm missing something. Nick.

[87MH]

Originally Posted by nickcrowhurst

The advert indicates this air conditioner is for commercial trucks, so perhaps such trucks have batteries with such a high capacity. Or perhaps I'm missing something. Nick.

I think what's missing is the fact that the 33 amps is for the fan only. The advertisement clearly states that an AC clutch is required......this unit requires an engine driven compressor.

13.6 volts X 33 amps is about 450watts. Less than 25% of the power than is required for any comparable 16K BTU AC unit.

[Marlboro Mafia]

I saw the part about the AC clutch. I heard about these on a XM Radio ad. Apparently new DOT regulations prohibit transfer trucks from idling for long periods of time. The ad was touting the Red Dot AC ability to operate without the truck engine running. The ad specifically said it would operate for 6 to 8 hours on a deep cycle battery.

Maybe I am looking at the wrong model, but according to the ad, they do have a model that is DC only, compressor and all.

[markdoane]

The link you posted to Red Dot goes to the 6100 model. I think you're talking about the 6900 model.
http://www.rdac.com/prod-cat-r6900.pdf

[Over59]

Need more info than the ads gives. Too good to be true. For 7 hours from a 27 the running amp draw has to be alot less. You could be it with 4 for the 150 amphour battery but what do you do the next night. 4 x 150 /2 = 300 ah. If draw is 25 then you have a night's worth of juice. If you are recharging from the tow vehcile you would need a rather high output regulator, no? What does that kind of duty do to a battery bank. Gott hurt.

Or you might try a pair of 8D battery for 500ah.

[71tradewind]

After reading the pdf I realized it only puts out 9000 btu at 12 volts ....this maybe fine for a Bambi but I think the bigger rigs will require more.

[Over59]

How much do they cost???