Air-conditioners and lithium batteries guide

Air-conditioners and lithium batteries guide

Air conditioners are complex and energy-intensive appliances, with a substantial demand on lithium battery use. However, with the right combination of battery type and correctly sized air conditioner, you can enjoy off-grid cooling. This guide will help you make that decision.

Firstly, you need to determine your air conditioner's power usage per hour and then multiply it by the hours you intend to run it. Factors that influence the power consumption of an air conditioner include:

  1. The size of the room or area being cooled.
  2. The air conditioner unit's efficiency rating.
  3. The temperature setting on the unit.
  4. The length of time the unit is running.
  5. The local climate and weather conditions.

We will categorize this article into two types of air conditioners: DC (12v, 24v, 48v) and 220v AC.

Starting with our recommended solution, the DC powered air conditioner has several advantages:

  1. It eliminates the need for an AC/DC power inverter, which typically has a power loss of 10% during DC to AC conversion.
  2. It consumes less power compared to 220v AC air conditioners.
  3. It is smaller and more compact.

However, it does have some drawbacks:

  1. It's not as powerful as a 220v AC air conditioner.
  2. It can be more expensive than 220v AC air conditioners.


    We can calculate the power draw by using the following formula. Here is an example with a 12v 500 wat Air conditioner:

    1. We know the power consumption (P) is 500 watts.
    2. We know the voltage (V) is 12 volts.
    3. We can use the formula: Ah = P / V (where I is current in amps).
    • Ah = 500 watts / 12 volts
    • Ah = 41.67 Ah(Amps per Hour)

    In this table we have already done the calculations for you using a 5500 BTU 12v and 24v air conditioner. Please keep in mind that these are guideline figures. Your actual results may differ due to a variety of reasons mentioned in the first paragraph.

    Now, should you get a 12v battery or a 24v battery pack? Here are some advantages and disadvantages for both:

    • 12v Advantages: Widely available, easier to find compatible chargers and equipment, often cheaper due to higher demand.
    • 12v Disadvantages: May require thicker cables for high current applications due to energy loss (resistance).
    • 24v Advantages: Can potentially use thinner cables. May require fewer batteries to achieve the same total system voltage.
    • 24v Disadvantages: Less common, may require specialized chargers, and compatible equipment might be more expensive or limited.

      Despite some drawbacks compared to a 220v AC system, we generally recommend using a DC air conditioner primarily due to its superior efficiency. Although you might invest more initially, you will get more runtime from your battery. Depending on your needs, you could potentially afford a smaller, more cost-effective battery compared to what you would need for a 220V air conditioner.


      Let's now consider 220v air conditioners.

      The advantages of a 220v air conditioner include:

      1. They can be extremely effective at cooling due to their power.

      However, they do have some cons:

      1. They require a power inverter, which typically adds about 10% power loss.
      2. They have a higher power draw compared to DC air conditioners.
      3. They are larger in size compared to DC air conditioners.
      4. While generally more affordable than DC air conditioners, the savings may be offset by the increased power consumption.

      To calculate how much power an air-conditioner uses is a little more complicated, but not that hard. It can be calculated using this formula:

      Apparent Power Needed (AC Side):

      • Apparent Power (VA) = Appliance Wattage (W) / Inverter Efficiency

      Current Draw from the Battery (DC Side):

      • Battery Current (A) = Apparent Power (VA) / Battery Voltage (V)

      Let's say your air conditioner uses 1480 watts (W) and your inverter has an efficiency of 90% (η).

      1. Apparent Power (AC Side):
        • VA = 1480 W / 0.9 = 1644.44 VA (rounded to two decimal places)
      2. Battery Current (DC Side):
        • A = 1644.44 VA / 12 V = 137.04 A (rounded to two decimal places)

      In this example, the air conditioner will draw 1480 watts of power per hour.

      The inverter will need to pull approximately 137.04 amps from the 12V battery to supply this power

      If this seems confusing, don’t worry, we have already done the calculations for you. Please keep in mind that these are guideline figures. Your actual results may differ due to a variety of reasons mentioned in the first paragraph.

      220v air conditioners offer maximum cooling power, but this comes with higher power usage. If you are looking for the most powerful cooling option, be prepared to invest in a larger battery pack based on your cooling needs.

      Here are some additional tips to reduce the power demand of your air conditioner:

      1. Ensure that the room is sealed off from outside, helping to keep the cool air in and the hot air out.
      2. If camping, park in a shaded area to lower the room temperature.
      3. The smaller the room, the less power your air conditioner will consume to maintain a comfortable temperature.
      4. It's best to use the air conditioner at night, especially while sleeping. Operating it during the daytime when it's hotter will drain your battery faster.
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