Are Power Inverters Bad for your Car?

There are many times that we wish we could plug-in something to our car or other vehicle while driving. It could be that you wish to charge your laptop, your phone, or perhaps even have a small television plugged in for long road trips. Whatever it is that you wish to power you will need a power inverter installed in your vehicle in order to provide the necessary one-hundred and twenty volt plug-ins needed for these appliances and electronics.

Power inverters take your vehicle’s direct current (DC) power and convert it over to alternating current (AC). AC power is what all of the electronics and appliances use in your home today. The inverter will connect to your battery directly on one side and on the other side it will have one or two one-hundred and twenty volt plug-ins just like what you would find at your home.

Over the past few weeks we have been writing numerous articles on power inverters in an effort to cover all of your questions. In today’s article we are going to be focusing on the common question of, are power inverters bad for your car? Let’s dive in and take a look!

Are They Bad for Your Car?

When it comes to using power inverters there is only really one thing on your vehicle that it can damage, and that is your vehicle’s battery. Most vehicles come with a standard twelve volt battery that is used for starting your vehicle. It can also provide power for your radio, clock, and interior lights for small periods of time while the engine is off. As I said before, power inverters connect straight to your battery and draw the DC power from your battery.

If you run your power inverter while your vehicle’s engine is off then you will be draining the battery. If left unchecked you can drain the battery until it is dead. You are then left with a dead battery and at the minimum will need a jump from another vehicle just to get your car going again. You also may or may not have permanently damaged your vehicle’s battery. Standard vehicle batteries are only meant to give that initial boost of power when turning the vehicle on. They are not meant for long term use. If their capacity falls under ninety percent then you could end up shortening the lifespan of the battery.

There are alternative solutions here to allow you run inverters while the vehicle’s engine is off, but before I get into that lets first take a look at what happens when your vehicle is running. If you have your inverter powered on while you are driving down the road, or even just idling, things are a bit different. When running your vehicle’s alternator is constantly producing power for the vehicle’s electronics and also to charge the battery. So, if you have a power inverter running and draining your power from your battery your vehicle’s alternator will be recharging your battery at the same time.

Now in most cases the alternator will be producing more power then the power inverter is drawing. In these examples you can run the inverter the entire time you are driving with little or no issues. If you have a larger power inverter hooked up though, say two-thousand watts or higher, then you could run into instances where the power inverter is drawing more power then the alternator can produce. When this occurs the alternator will try to leverage some of the stored power in the battery to make up for its shortcomings. This will result in your battery being drained completely even while you are driving down the road.

This is why it is so key to know the wattage of exactly what you are trying to power with your inverter. Some appliances have their wattage draw on the labels but some only have amperage. Not to worry though as you can still figure out wattage rather easily. All you have to do is take the amperage number and multiply it by the volts. Volts are what type of plug-in the appliance uses. Most will end up using the standard one-hundred and twenty volt plug-in. So, what you have here is amperage times volts equals watts. As an example let’s say you have a coffee machine rated at five amps. Five amps times one-hundred and twenty volts equals out to six-hundred watts.  It is also best practices to go twenty or thirty percent higher then your calculated power requirements. This gives you a buffer zone so that if you did miscalculate or if you have additional equipment that needs powered you have the room.

Not only is it important to know the wattage requirements and the amps produced by your alternator it is also key to understand what sized of inverter you should buy. So, again going with that coffee maker you would need one-thousand watt inverter. (Adding thirty percent to the six-hundred watt number gets us there.)

Alternative Solutions

Now if you wish to only power your inverter while driving and only using one-thousand watts or less then you should be fine to use your vehicle’s existing equipment. You most likely will not have to make any modifications. However, if you aim to power high wattage equipment while driving or if you wish to power smaller equipment for long periods of time while your vehicle is off then it is time to look at some alternative mods you can do to your vehicle.

As I said, there are two situations here. First lets look at powering high wattage equipment, say two-thousand watts or more, while your vehicle’s engine is on. Without modifications you can run into the issue we stated earlier where the alternator cannot produce enough energy and the battery ends up getting drained as you are driving down the road. The solution here is actually quite simple, all you need to do is purchase a high capacity alternator. Alternators have a maximum amperage that they can produce. By purchasing a high capacity alternator you are increasing the amperage limit which in turn increases the amount of power that the alternator can produce. Now there are many examples of high capacity alternators out there today and as you know each vehicle will require different fitting parts. So, I will not go as far as recommending a product here but instead suggest you consult with your dealership or local mechanic. Before consulting with them it is best to know your current alternator’s amperage limits. You can then begin to determine exactly what size high output alternator you will need.

The other scenario is that you may not be using a large amount of power but you DO want to run the power inverter while your vehicle is off. With your standard twelve volt battery you can only really get about thirty to sixty minutes of runtime before your battery is dead. To get around this you can install an alternative battery or a second battery for your vehicle. This second battery should be a ‘Deep Cycle’ battery. These deep cycle batteries are meant to last much longer then your standard automotive battery. Remember earlier how I stated that the battery cannot fall under ninety percent capacity? Well a deep cycle battery can drop as far as fifty percent! That is a significant difference.

The deep cycle battery will be charged just like your other battery is. When the vehicle is running the alternator will charge both batteries as you drive. Then when you shut the vehicle off you will be ready to hours of charge time on your deep cycle battery. If you do notice that the batteries aren’t charging as fast as you like you may also look into the high output alternator we mentioned above as well.

Again, I will not get into the install process of adding an alternative battery to your vehicle. Instead I recommend this guide I found. It gives you a basic understanding of what needs to be done. If you find you are still confused on how to do it then I recommend visiting your dealership or local mechanic and asking for heir assistance.


So in closing folks power inverters are not really bad for your car. The only thing to watch for, or look out for, is your car’s battery. If left unchecked or if you did not measure how much wattage you are drawing from the battery then you could end up with a dead battery. When selecting power inverters remember to get the proper size and to also understand how you wish to run the inverter. Will you be using it as you drive down the road? Or, will it be used with the vehicle off perhaps at a tail gate party? Determining this will allow you to figure out the next steps and if you need to move forward with an alternative solution for your vehicle.

Thanks for reading,

Alec Johnson

You may also like