Originally Posted by petefoss
What's a typical kWhr/day for AC in a small camper? Just trying to get a handle on how big a battery bank it would take. Given that 1 kWhr is about 100 amp hours at 12V with losses, you would need probably 500 -1000 amp hours? I need at least 100 amp hours just to run my fridge!
FYI the battery in a Chevy Volt gen 1 was about 10 kWhr usable and weighed 500 pounds.
Lithium battery weight (chemistry used in most RVs) is approximately 30 pounds for 100 Ah, so roughly 25 lb/kWh.
At night, when itís cooler, an efficient typical RV A/C runs on about 1,000 Watts of power. Based on my experience, Iíd estimate it would need to average less than 5,000 BTU/hr in a well-insulated Class B, so no more than 50% cycle time.
Many of the B vans set up to do this have +/- 600 Ah of useable lithium capacity, or just over 7.6 kWh. In theory it should be enough for 8~10 hours through night. Reports suggest itís in right ballpark.
The Travato lithium has a little more battery capacity (8.7 kWh going from memory), and they estimate 6~8 hours while running other items like electric refrigerator. I think thatís based on daytime conditions, and also using an inverter to power the 11,000 BTU/hr Power Saver.
Newer vans that I saw at Tampa Super Show are now also going with a DC air conditioner that not only runs without an inverter, but is more efficient according to manufacturerís published data. Additionally, at night when cooling loads are lower, the A/C can run slower, making it even more efficient.
RoadTrek, now back in business, offers their EcoTrek batteries in ď200Ē size modules, which I assume to be 200 Ah. The most expensive Mercedes Sprinter vans are listed with up to 800 (Ah?), which is about 10 kWh. Iím not certain if thatís useable capacity, or if it has to be derated by about 20%.
To run an A/C in a van all day, or 24 hours, would take about 30 kWh, which isnít practical at this time. Thatís when youíd start engine and recharge batteries as quickly as practical.