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.
Nick Crowhurst, Excella 25 1988, Dodge Ram 2500 Cummins Diesel. England in summer, USA in winter.
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