You know what no one among the car-owning public was clamoring for?
Having an auxiliary car battery for their vehicle that could fail and cause issues with the ignition system, the auto stop-start function, brake assist, or roughly a dozen other crucial functions.
We learn from the crew at TikTok user Royalty Auto Service (@royaltyautoservice) in Georgia that an auxiliary car battery is becoming more common on European and domestic cars. And that, of course, means double the chance of a failure that, in most cases, will require both batteries to be replaced.
In a TikTok video that’s been viewed more than 368,000 times, Royalty owner Sherwood Cooke Jr. shows us a 2021 Volvo V90 that has a main battery and an auxiliary car battery that lots of owners are unaware of.
What do the extra batteries do?
“This one had a brake issue with a parking brake, was not functioning properly,” he said.
“They’ll come in and they’ll say, ‘Hey, I don’t know what’s going on with it. I’ve had a new battery put in it’ and they’ve had that. That battery put in it, but they haven’t had the auxiliary battery replaced.”
Auxiliary car batteries have become essential in modern vehicles to support complex electrical systems. They help stabilize power during engine start, preventing voltage drops that could disrupt electronics.
They also power key systems like alarms, keyless entry, and infotainment when the engine is off, reducing strain on the main battery.
In hybrid and electric vehicles, the auxiliary battery supports 12V systems, allowing the high-voltage battery to focus on propulsion. Additionally, they enhance safety in autonomous vehicles by providing backup power to critical systems.
Get your wallet out
Since it would be time-consuming and imprecise to determine which battery is involved in any particular electrical issue that pops up, Cooke says the default solution is to replace both batteries.
If you’re handy with the tools required and confident enough to do a self installation, two new batteries should run around $500 or $600. Folks on Reddit report a dealer quote of almost $900 for their staff to handle the installation.
Of course, the increasing complexity of today’s cars means there’s plenty of expensive surprises just waiting to pull money out of our pockets and into the hands of a mechanic.
Here are some of the most wallet-draining fix-ups:
- Transmission Replacement: A failing transmission can set you back between $5,266 and $5,469.
- Hybrid High-Voltage Battery Replacement: For hybrid vehicles, replacing the high-voltage battery can cost around $6,645 to $6,719.
- Cylinder Head Replacement: Issues here can lead to repairs costing between $3,575 and $3,928.
- Catalytic Converter Replacement: Replacing a catalytic converter that’s been pilfered by parts thieves can cost between $2,224 and $2,309.
- Turbocharger Assembly Replacement: A faulty turbocharger can lead to repair costs ranging from $2,028 to $2,429.
Viewers lament both batteries
Commenters on the clip weren’t fans of the growing use of auxiliary car batteries, and the headaches they’re likely to cause.
“Aux batteries are great. GM puts them in easy to access location every time. (All sarcasm, and I hate auto stop),” one of them wrote.
This warning came from an owner who’d lost the battle of the batteries. “The little battery can kill the main battery too,” they wrote.
And an apparent mechanic was honest about his feelings on the second batteries and their impact on his business.
“This kind of stuff keeps us in business. Cars just aren’t built for do-it-yourselfers anymore. You can’t even change your own brakes without a scan tool because of the electronic parking brakes,” he wrote.
@royaltyautoservice Lots of weird issues because of this! #mechanic #mechaniclife #diy #automotive #cartok #volvo #fyp #foryou #viral #tips ♬ Pop beat BGM / long version(1283324) – nightbird_bgm
The Daily Dot reached out to Royalty Auto Service via email.
Internet culture is chaotic—but we’ll break it down for you in one daily email. Sign up for the Daily Dot’s web_crawlr newsletter. You’ll get the best (and worst) of the internet straight into your inbox.
