A good baseline is to have your EV's 12V battery tested about once a year, or before any long trip, and to pay attention to your main battery's range and charging behavior on an ongoing basis rather than waiting for a scheduled check. The two batteries in your EV — the small 12V and the large main pack — age differently and fail differently, so "battery testing" really means two separate things.
The 12V Battery: Test Annually, or at the First Warning Sign
The 12V battery powers the low-voltage systems that "wake up" your EV — door locks, onboard computers, contactors that connect the main battery. If it dies, your EV can be completely unresponsive even with a full main battery charge, which surprises a lot of owners.
Test it:
- Once a year as routine maintenance
- Before a long road trip
- If you notice slow power-up, flickering interior lights, or the car struggling to "wake" from being parked
12V batteries typically last 3-5 years, similar to a gas car's battery, and testing is quick. If yours is dead or dying, 12V battery assistance starts at $99 and can get you back up and running without needing to tow the vehicle.
The Main Battery: Monitor, Don't Just Test
The main traction battery doesn't have a simple annual "test" the way a 12V does — most EVs continuously report battery health data through their dashboard or app. Instead of scheduling a test, keep an eye on:
- Gradual range loss compared to when the car was new
- Charging speed slowing down noticeably at the same charger
- Inconsistent range estimates that don't match your driving
- Warning lights related to the battery or charging system
If you notice a sudden or sharp change rather than gradual, normal aging, it's worth getting checked by a technician rather than waiting.
Warning Signs That Mean "Test It Now," Not Later
- Dashboard warning lights related to battery or charging
- The car won't power on despite the main battery showing charge
- Charging sessions that won't initiate or stop unexpectedly
- Noticeably reduced range after moderate weather changes (some loss in extreme heat or cold is normal, but a dramatic drop isn't)
A Simple Annual Routine
- Have the 12V battery load-tested once a year.
- Review your battery health/range data in the app every few months.
- Note any charging speed changes and mention them if you get service done.
- Don't ignore repeated warning lights, even if the car still drives fine.
What Happens If You Skip It
Skipping 12V testing is the more common regret — a dead 12V battery is one of the most frequent roadside calls EVs generate, and it's usually preventable with a simple annual check. Main battery issues are rarer but more expensive to ignore if something is actually wrong.
The Bottom Line
Test your 12V battery yearly and before long trips; monitor your main battery's range and charging behavior continuously through your car's own data. Catching a weak 12V battery before it fails is far less hassle than dealing with it stranded in a parking lot.
If your EV won't power on or is showing battery warnings, call 321.662.1053 or request help and we'll get it diagnosed.