How Long Does an Auxiliary Battery Last?

When a dual battery system is added to a vehicle, it is usually because accessories have been added to the vehicle that are not factory-standard, and the primary battery in the vehicle does not deliver sufficient power to drive these new accessories effectively. Understand that we’re not saying you need an auxiliary battery to power, say, a phone charger or a stand-alone GPS. It’s more like if you’ve converted a cargo van into a camper, and you’ve added a fridge, microwave, entertainment system… you get the idea. In that case, it can be highly advantageous to have one battery to deal with starting your vehicle, and another to operate your accessories. That way, once you’ve reached your campsite, you don’t have to worry about drawing power from your primary battery.

So, how long will your auxiliary battery last? Properly cared for and maintained, you can expect anywhere from 18 months to 3 years of life from an auxiliary 12-volt battery. Much will depend on frequency of use, and how well the battery is protected. Rough roads can cause the cells to break down, reducing the lifespan. Allowing it to drain to less than half of its rated capacity will also reduce the life of the battery. And of course, if you are parking your vehicle for any length of time, you should use a battery maintainer.

Signs that your auxiliary battery needs to be replaced include:

  • Accessories not operating properly
  • Accessories not working at all

If you think your auxiliary battery could be failing, have it checked. A professional mechanic can test your auxiliary battery, and replace it if necessary.


The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.

GET A QUOTE

Related articles

How to Dispose of Car Batteries
Car batteries have chemicals which can damage the environment. Dispose of car batteries at a battery recycling center or a local auto supply store.
How to Change Battery Cables
Although simple in nature, battery cables (https://www.yourmechanic.com/article/symptoms-of-a-bad-or-failing-battery-cable) are one of the most important components of a vehicle’s electrical system. They serve as...
How to Buy RV Batteries
RV RV (recreational vehicle) batteries come in many different types, and what type is best depends on the useage and conditions the RV (https://www.yourmechanic.com/article/5-essential-things-to-know-about-owning-an-rv) will be exposed to. Unlike cars, RV’s use multiple batteries. These batteries are used to power...

Related questions

How Does the Starter Work in Your Car?
Back in the old days, cars had a hand-operated crank that had to be spun around for quite a while by the driver in order to start an engine. The reason for this was simple. In order to start a...
Car cannot be started
Hello. It sounds like your car’s battery is starting to go bad or is bad already. It doesn’t sound like a serious problem with the engine exists. In addition to the possibility that you have a bad battery, it is...
Car won't start & lights are all off
Greetings! The problem indeed likely lies within the battery itself. Some batteries (https://www.yourmechanic.com/article/how-to-diagnose-a-car-battery-drain_2) get to a point when it will lose its ability to hold or receive an electrical charge. When this happens it is nearly impossible to revive a...

How can we help?

Our service team is available 7 days a week, Monday - Friday from 6 AM to 5 PM PST, Saturday - Sunday 7 AM - 4 PM PST.

1 (855) 347-2779 · hi@yourmechanic.com