Do Power Inverters Draw Power When not in Use?

Power inverters are a great tool to have around rather you are an experienced RVer or if you just wish to have some extra power during a long road trip. They provide you and your vehicle with alternating current (AC) power that allows you to power basic appliances like laptops, television, gaming systems, coffee makers, and so much more. They also come in a variety of sizes so that you can ensure that you can power whatever you need.

This power doesn’t come from thin air though. It comes from your vehicle’s batteries or your vehicle’s alternator. For an example, lets say that your vehicle’s engine is turned off, the power inverter is plugged in, and you have your laptop plugged into the inverter. The power inverter will provide your laptop with the needed power to charge but that charge has to come from somewhere. This charge comes from your vehicle’s battery. If left unchecked the power inverter can drain your battery to the point of where it is dead. This will leave your car unable to start without a jump and could also leave you stranded. This is not a good place to be.

Your standard twelve volt automotive battery is not intended for the long term use from a power inverter. Instead, they are meant for quick burst of energy to start your vehicle’s engine and electrical systems. Because of this the battery will not last long under the long term load of a power inverter. Some folks opt for installing a secondary or alternative battery known as a deep cycle battery. These deep cycle batteries can last much longer then your standard battery but even they will eventually drain to the point of no return.

It is important to monitor how long you have appliances plugged into your inverter so that you do not wind up with a dead battery. It is also important to recognize that your power inverter can still drain energy from your vehicle even when nothing is plugged into the AC side. (The AC side is where your laptops or other appliances would plug into.) When the power inverter is left with no AC connections plugged in it can still end up drawing five to ten percent of its rated power. So, if you had a one-thousand watt inverter connected it could end up drawing fifty to one-hundred watts of power even with no AC connections plugged in.

While this will be a much slower drain then if you had appliances plugged in it is still a drain of power that can leave you in a bad situation. Let’s say for example you took your truck out for a weekend camping trip. You had the inverter plugged in and it worked fine. When you got home Sunday night you put the truck away and went about your business. The power inverter had the appliances unplugged BUT it was still on and connected to your vehicle’s battery. The week passes and come Friday night you want to take the truck out again. You go to start only to find that the battery is dead.

This is a prime example of what can happen when power inverters are left on. The lessen from this short example and from this article is to always always turn your power inverter OFF when you are done with it. Some folks will go as far as disconnecting the battery connection from the inverter as well. In most cases this is not necessary. Having the inverter switched to OFF will be enough to ensure that there is no further power drain on your vehicle.


In short folks, to answer the question of this article, yes power inverters can still draw power when there are no appliances or electronics connected to them. If the inverter is connected to your vehicle’s battery and the inverter is left on it can draw five to ten percent of that inverter’s power. This will equate to a slow drain, but it is still a drain on power. When you are done with your inverter be sure to unplug everything and to turn the inverter to OFF before leaving your vehicle.

There is ONE more thing to mention here before I close this article and that is RVs or motorhomes. These types of vehicles can get power from both your standard DC alternator/battery but ALSO from AC current like that of a generator or a plug-in connection at a campground. In most cases these vehicles also have what is known as a Converter. A converter works the opposite way that a power inverter does. The converter will convert the AC energy coming into your vehicle into DC energy. This converted DC energy will actually charge your batteries. It is in these cases where you CAN leave the power inverter on without worry as the batteries of your vehicle are being charged so there is no risk of the batteries dying from the inverter’s power demand.

I hope this article was helpful and was able to answer some of your questions.

Thanks for reading,

Alec Johnson

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