12V / 16V battery
Tesla & EV 12V and 16V battery replacement
The small low-voltage battery runs the computers, locks and screens, and it switches on the high-voltage system. When it weakens, the car can refuse to unlock or drive even with a full main battery. We replace it and carry out the reset and configuration the car needs.
Common on Model 3 · Model Y · Model S · Model X · ID.4 · ID.6 · Han · Dolphin
Symptom checker
What is your car doing?
Pick what you notice. We’ll show the system it is often related to and what to send us. Only a check at the workshop can confirm the cause.
- A 12V or 16V battery warning Often related to 12V / 16V battery
- The car won’t wake up or unlock Often related to 12V / 16V battery
The work
What the check covers
- Low-voltage battery health and voltage
- Charging from the DC-DC converter (the PCS on a Tesla Model 3 or Model Y)
- Power drain while the car is asleep
- Stored low-voltage alerts
What we repair
- 12V battery replacement
- 16V battery replacement
- Reset, configuration and unlock after replacement
In detail
What the low-voltage battery does
Every electric car still has a small battery, like the one in a petrol car. It runs the computers, door locks, windows and screens, and it powers the contactors that connect the high-voltage battery when you drive. The high-voltage battery keeps it charged through a DC-DC converter.
Tesla 12V and 16V batteries
Older Tesla models use a 12V lead-acid battery. Newer Model 3, Model Y, Model S and Model X cars use a 16V lithium-ion battery. After a 16V battery is replaced, the car needs a reset and configuration before it accepts the new battery, and we do that as part of the job.
VW ID. and BYD
The VW ID.4 and ID.6 and the BYD Han and Dolphin also have a 12V battery for their electronics. On the ID. models, a weak 12V battery can cause warnings that look like much bigger faults, so it is worth testing first. See the VW ID. page for more.
System map
Other systems we work on
Illustration: a generic electric-car chassis seen from above, not any particular make or model.
FAQ
Questions owners ask
What is the difference between a 12V and a 16V battery on a Tesla?
Older Teslas use a 12V lead-acid battery. Newer ones use a 16V lithium-ion battery, which lasts longer but has to be reset and configured after it is replaced. The model and year tell us which one your car has.
Can the 12V battery fail even if my main battery is full?
Yes. The low-voltage battery is separate from the main one, the high-voltage battery pack. If it fails, the car may not wake up or connect the main battery, so it will not drive.
Does heat affect the 12V battery?
Yes. Heat shortens the life of lead-acid batteries, so they can fail sooner in the UAE than in cooler countries. If your car shows a low-voltage alert, have it checked before it leaves you stranded.
My new battery keeps going flat. Why?
The battery may not be the problem. On a Tesla Model 3 or Model Y the PCS charges the low-voltage battery, and a fault there drains even a new one. We check the charging side too; see HV battery and power electronics.
Car won't wake up?
Send the model, year and a photo of the alert on WhatsApp.