When you’re off-grid, you have to make sure that you’re prepared for the coldest months of the year. Running a space heater off an Inverter can be a great option when off-grid however you need quite a big battery bank to sustain it over time.
In this article, we show how to pick an inverter to run a space heater match the inverter to a battery, and how long you can the space heater with different battery options.
Choosing an Inverter for a Space heater
If you have a space heater and want to use it with your inverter, you need to make sure that the inverter can handle the load. A good place to start is by looking at how many watts (W) your space heater needs to run. The wattage of a space heater varies depending on the model and size. Smaller space heaters with less power use less electricity than larger ones with more power.
The average wattage of most space heaters is between 1,000 and 2,500 watts. However, there are some high-powered models that use as much as 8,000 watts of energy per hour!
To run an 1800-watt space heater you’ll need a 2000-watt inverter. A 2000-watt inverter with 6000-watt surge watts is a powerful inverter that can run high-wattage appliances. This includes a space heater, hair dryers, and some electric ovens.
How Long Will a 2000-Watt Inverter Run an 1800-Watt Space Heater?
The duration that the inverter can run the space heater will depend on the battery. An inverter converts direct current (DC) from the battery to alternating current (AC) that the space heater can use.
To get the battery size we need we’ll first determine how many amps the space heater will be drawing through the inverter and get the capacity required.
How Many Amps for 1800 Watt Space heater
To find the size of the battery, you divide the watt-hours by the voltage.
In this case, you have a 12-volt system, so you divide 1500Wh by 12V and for a 24V system, you divide by 24V.
1800/12 = 150 Amps
1800/24 = 75 Amps
To power the space heater you need a battery that you can safely pull 150 amps per hour for the 12v system and 75 amps per hour for the 24v system.
How Many Amp-Hours for a Space Heater
150 amps is a lot to pull from any system and will require bigger wires and a bigger battery so it is best to go with a 24v system pulling 75 amps. You can also consider a 36v or 48v inverter as you’ll need even smaller wires and batteries.
To pull just over 75 amps per hour you’ll need a 24-volt 300Ah LiFePO4 battery bank.
You can also choose a smaller battery bank if you are running the space heater for shorter periods of time.
What Size Battery to Run a Space Heater for 15 minutes
Rather than using a space heater over the course of a full hour you can opt to heat your room over intervals of a few minutes. Some space heaters come with a thermostat pre-installed and allows you to set the temperature you want to reach. So how much power would you need for 15 to 30 minutes of use?
Since we already have a figure when using the space heater for an hour for 30 minutes we can half the power use and for 15 minutes we half it again.
| Length in time | Watt-hour Requirements | Battery (24v) |
| 1 hr | 1800Wh | 300Ah |
| 30 minutes | 900Wh | 150Ah |
| 15 minutes | 450Wh | 100Ah |