This post may contain affiliate links. If you click an affiliate link and make a purchase, I may earn a commission at no extra cost to you whatsoever.
You may not be able to power your genset as you move in your RV yet you want to power some electronics – perhaps to warm some food in a microwave, or power the fridge.
If a genset is not an option, what size of inverter can you use? Is a 1,200-watt inverter large enough to power your RV?
In this post, we’ll look at what appliances you can power with a 1,200 watt inverter, what you should consider purchasing with your inverter to use it easily, reliably, and safely – batteries, DC wire sizes, and fuses and what features you should look out for when purchasing your next inverter.
How Much Power a 1,200 watt Inverter Uses?
At full load, a 1,200 watt inverter can consume as much as 1,270 watts depending on its efficiency. Note that this is more than the sticker rating of 1,200 watts.
This is because the inverter is not 100% efficient as some of the power drawn from the batteries is wasted during the energy conversion process from DC to AC and is not available for your electrical appliances.
In this case, an inverter power consumption of 1,270 watts, assumes an inverter efficiency of about 95% efficient. This can be higher if the inverter efficiency is lower.
Most inverter manufacturers specific and inverter efficiency of between 85 -95%.
Inverter Power Consumption when No Appliances Are Connected
Inverters still draw power from the battery even when no appliance is connected provided they are switched On.
The no-load power draw can vary from one manufacturer to another (based on inverter design) but as a rough guide, a 1,200 watt inverter can draw as much as 10 watts when no appliance is connected.
For this reason, if no appliances are drawing power from the inverter, switch it off as this power draw adds up over time and can drain the battery.
Note, some inverters have energy efficiency mode – the eco mode that can reduce this power draw by as much as 80% when activated.
Check your inverter manual if it has one and how to activate it.
What Can a 1,200 Watt Inverter Run?
At full power, the 1,200 watt, 12V inverter can power one or several appliances connected to it provided their combined continuous power draw is up to 1,200 watts, and surge power draw does not exceed about 2,400 watts (~2X continuous power rating).
Note. The continuous power draw assumes that the inverter is installed in a well-ventilated space otherwise, it may shut down to prevent damage when excessive power is drawn.
Additionally, the combined surge power draw of the appliances should not exceed the inverter’s – consult your inverter’s owner manual.
Modified sine-wave vs. Pure sine-wave inverters
Also note that some appliances such as microwaves, fridges, CPAP machines, and laptops may not run well when connected to modified sinewave inverters.
To avoid a situation where one of your appliances may not work well with your modified sine-wave inverter, whenever possible invest in a pure sinewave inverter.
Here is a list of examples of appliances that you can connect to the inverters
- Laptop – 40 watts
- 42″ LED TV – 50 watts
- 1,000 watt microwave – 1,000 wats. If the power consumption is close to 1,200 watts consider operating the microwave at a fraction of its full power.
For example, a microwave with a power consumption of 1,200 watts when run at 70% of its full power, only uses up about 840 watts.
You should also consider using the microwave for quick durations and LP for cooking as the power draw on the battery can be considerable if you use the microwave to prepare meals with a longer cooking duration (~ > 5 -10 min) depending on the battery bank capacity.
- Fridge – 100 watts
Total power consumption is 1,190 watts.
You may also be interested in this post: What can a 400 watt inverter run?
What Size of Battery to Use with a 1,200 Watt Inverter?
You can use 2 x 12V, 200 Ah AGM, or GEL batteries connected in parallel or 1 x 100 Ah LiFEPO4 battery to power the inverter or larger capacity batteries.
This battery capacity can power your inverter for about 1 hour when the combined load is drawing 1,200 watts (maximum inverter power).
What else you should consider using with your inverter?
In addition to the batteries, consider investing in both a battery monitor and charge controller.
- A battery monitor to visually monitor the state of charge of the battery, how much runtime of battery power is available how much power is flowing into and out of the battery.
- A 30 amp charge controller or greater to charge the battery bank. It can handle up to 440 watts of PV power at 12V and 880 watts at 24V.
- Solar panels to keep the batteries charged
What key features should you look out for?
#1. Check if your inverter has a power-saving mode. This minimizes the power drawn by the inverter when no appliances are connected so that you do not have to remember to switch off the inverter when not in use.
#2. Does the inverter have a transfer switch? With a transfer switch, the inverter can automatically switch and supply power to the connected appliances using shore power (if available) or using energy from the batteries (when shore power is not available).
What Size of DC wire to use with the Inverter?
Use 6 AWG or larger sized battery to inverter DC cables for the 1,200 watts, 12V inverter. Keep these DC cables as short as possible to limit the voltage drops that affect the inverter power output especially when the inverter is drawing maximum power.
A good quality 1,200 watt inverter can supply up to 1,200 watts of continuous power and typically up to 2,400 watts of surge power provided is installed in a well-ventilated area.
While there are several possible battery combinations that you can use to power the inverter, 2 x 12V, 200 Ah AGM or GEL batteries connected in parallel or 1 x 100 Ah LiFEPO4 battery when used can provide about an hour of runtime at maximum power.
Examples of appliances that you can connect to the inverter include a fridge, washing machine, microwave, TV and laptop, and others. Make sure you do not exceed its power limits.