Ideal for use with off-grid homes, cabins, and alternative energy systems a 200Ah battery can extend your normal home comforts. While in the summer heat, you need to run your air conditioner to cool down. So can you rely on a 200Ah battery to run an air conditioner?

A 200Ah battery can only run an air conditioner for up to 28 minutes. We tell you why you should only limit to this timeframe and what you can do to go around this. 

Power for an Air Conditioner

The most important thing when choosing an air conditioner is to make sure that it will cool down your space without using too much energy. If you plan on using solar panels and batteries to power your home, then you’ll want to use as little electricity as possible so that your batteries last longer.

A typical 10,000 BTU air conditioner is enough for a small room or even a cabin. This air conditioner will have a wattage of around 1000 watts. 

Air conditioner Watt-Hour Energy Requirement 

The amount of energy used by an appliance is measured in watt-hours. The time it takes to use that appliance dictates how much energy it uses. This is calculated by multiplying the wattage of your air conditioner by the number of hours you will run it.

Watt-Hours = Watts X Hours 

If you want to use an air conditioner for 1 hour, you will need 1000 Wh.

This number will help us determine how long the battery can run the air conditioner.

How Many Amps does an Air Conditioner draw?

The amp drawn from the air conditioner will tell us whether the battery can support the air conditioner.  A 1000-watt air conditioning unit will need around 8.33 amps to run when using it from the standard 120V outlet.

This is the number of amps that it will be drawing from the inverter. Depending on the DC voltage of the inverter you can calculate the number of amps the air conditioning unit will be drawn through the inverter.

To get the number of amps you divide the Watts by the voltage of the system. 

For a 12v system:

1000W/12= 83.3 amps 

You need a battery that can support 83 amps pull from the air conditioner. Will our 200Ah battery do that?

How Many Amps can you Draw from a 200Ah Battery?

Amp-hour rating in batteries gives the charge in amps that can be drawn from a battery over a specific time given in hours.

A Deep Cycle Battery battery is intended to produce the charge for a long period of time like 20 hours. So for a 200 Ah battery, it should produce at least 10 amps over a 20-hour period. 

However, you can go higher or lower depending on the appliance you are using.  Deep cycle batteries are recommended to be discharged at 20% of their capacity so for a 200 Ah battery the max discharge per hour would be 40 amps meaning it can last 5 hours.

How many watt-hours is a 200 Ah Battery 

You can use the following formula to determine how many watts can be drawn from a battery.

Watts = Volts x Amps

So if your battery is 12v and has a 200 Ah capacity, then you can draw 2400 Watts from it. This is for the full battery cycle. With the 40 amps max draw it means you can get 480 watts max per hour. You can push this to 50 amps or 600 watts per hour with LiFePO4 batteries. 

How Long Will a 200Ah Battery Run a 1000-Watt Air Conditioner?

Looking at the parameters required to run an air conditioner and the capabilities of a 200Ah battery then it won’t be able to support these requirements. However, you can choose to run it for a few minutes with the power available. 

We already know the battery can support 480 watts but we need 1000 watts for the air conditioning to run for an hour. So how long is 480 watts? 

(480/1000) = 0.48 hrs 

In minutes 0.48 x 60 = 28.8 minutes 

A 200Ah 12v battery will run an air conditioner for 28 minutes. This is without any other appliance drawing power from the battery.

Conclusion

If we were to use a 24v 200Ah LiFePO4 battery bank it can support the 41 amps drawn from the air conditioner. This battery can last up to 5 hours without recharging the battery.  With the addition of solar panels, you can run the air conditioner for a few more hours.