Updated: May 27, 2020
So you want to know how long your air conditioner will run on your battery bank? Sounds like a simple question? Well KINDA!
There is a direct correlation between your air conditioning units efficiency and the outside air temperature. When the outside air temperature increases so will the air conditioners energy consumption.
Lets break this down, AMBIENT TEMPERATURE up = BATTERY TIME down
Simple Example 1: Nomadic Cooling 3000
@ 82F unit uses 554W
@104F unit uses 725W
Lets do some math with a hypothetical air conditioner that uses 500W at 80F and 1000W at 100F to make the math easier.
@80F unit uses 500W
@100F unit uses 1000W
You have 2 12V 100AH Batteries
@80F = 2X12=24.... 24x100=2400watts... 2400w /500w 4.8HRS
@100F = 2X12=24.... 24x100=2400watts... 2400w /1000w 2.4HRS
This oversimplified example hopefully helps explain why outside temperature is so important when planning your battery bank size and understanding how ambient temperature affects consumption.
The efficiency spread can be greater at times for a variety of reasons. You will need to remember this when calculating total air conditioner run time. Its best not to plan for the best case or the worst case. It is best to plan for your typical conditions.
Ask yourself, when, where, and how often you plan to use your air conditioning unit.