Tesla’s new 12V Li-Ion battery dying rapidly under certain conditions – here’s how to prevent it

dead 12v

Tesla has switched their cars to a new 12V Li-Ion battery, hoping to resolve a long-standing issue of the traditional lead acid batteries dying much faster than they typically do in internal combustion engine (ICE) vehicles.

It appears as though the problem hasn’t been completely resolved as numerous owners in Europe are reporting the new battery can also fail very quickly under certain conditions.

The problem only impacts newly delivered vehicles with a lithium iron phosphate (LFP) battery, where the 12V Li-Ion battery can die within 20 minutes of the vehicle’s main battery reaching a state of charge (SOC) less than 10%.

Just like when the lead-acid battery would die, this leaves the vehicle stranded and undriveable.

Making the problem worse, owners have so far been unable to jump the new Li-Ion battery with a lead acid battery.

One theory for this is because it has a higher voltage (15.5V), and since lead acid batteries have a maximum voltage of 12.8V, it can’t charge the Li-Ion battery.

Tesla is aware of the issue, and believes it is happening because the LFP battery hasn’t been calibrated properly since leaving the factory.

With an uncalibrated battery, the computer is estimating it still has some range left, but in reality it is actually at 0%. When there is no power in the main battery, the 12V isn’t charged anymore and dies within minutes.

Tesla has already issued an internal memo recommending new owners charge their LFP battery to 100% as soon as possible after taking delivery.

This will calibrate the battery and the computer will know more precisely how much range the battery has left in it.

Tesla is also recommending to avoid running the battery to below 10% until you have performed the calibration.

Despite the vast majority of the cases occurring when the main battery is at a low SOC, there have also been reports of the Li-Ion battery failing when the main battery is as high as 50% SOC.

Have you experienced this issue in your new LFP Model 3? Let us know in the comments below.

About Darryn John 5752 Articles
Founder and Editor-in-chief of Drive Tesla Canada | Darryn@DriveTeslaCanada.ca Have a Tesla tip? Email tips@driveteslacanada.ca, or DM us on Twitter @DriveTeslaca