Which Tesla battery has gone?
The high-voltage pack under the floor drives the wheels. Alongside it sits a much smaller low-voltage battery that wakes the car up and runs the door locks, lights and screens. The MTA notes that hybrids and EVs all still carry one of these.
When the small one goes flat, the car may refuse to wake up or let you in, even with plenty of range showing. AA New Zealand says that when an EV won't start, its 12V battery may have gone flat, and that short trips may not be enough to keep it charged.
If the message on the screen mentions the high-voltage battery, that's a different job altogether. Photograph it, with the kilometres showing, before you ring anyone.
What makes a Tesla battery job bigger or smaller?
We don't publish prices, but the things that move the number are easy to list. Which battery it is comes first. Then whether the warranty still covers it, and whether the fault can be repaired rather than the part replaced.
Read the warranty document that came with your Tesla before agreeing to anything on the big pack, and look at the cover for the high-voltage battery as well as for the car as a whole. If there's any chance it's covered, put the fault to Tesla in writing first.
For the small battery, ask for a test before a replacement. A battery that's simply been run down isn't always a dead one.
What a Tesla still needs looked at
- The brakes. Regenerative braking (the motor slowing the car) saves the pads, but friction brakes are still fitted and still need inspecting.
- Brake fluid, which soaks up moisture over time in any car.
- Tyres and wheel alignment, checked for wear right across the tread.
- Steering and suspension.
- The cabin air filter.
- The battery's cooling system. AA New Zealand says the coolant that cools an EV battery needs checking and replacing at regular intervals.
- The reduction drive oil (the EV's gearbox oil), in the grade the maker specifies.
Tesla service centre or a local mechanic?
Warranty claims and software faults go to Tesla first. Nobody without high-voltage training should be anywhere near the orange cables.
Tyres, brakes, suspension, alignment, wipers and air conditioning are another matter. A local mechanic can do that work, provided they're trained and equipped for high-voltage cars, so ask straight out how many EVs they see in a month.
On warranty worries, the MTA says a qualified independent mechanic should be low risk when the work follows the maker's guidelines and specifications. Tell us the model and what the car is doing. A local mechanic who specialises in your car.
Why a yearly look still matters
Tesla doesn't require regular maintenance, and that has a downside. In German and Austrian inspection results, TÜV ranked the Model 3 last among newer cars and gave the lack of required maintenance as part of the reason.
Those results are European, but a WoF looks at much the same things: tyres, brakes, steering and suspension. A once-a-year check before the inspection is how a Tesla owner stays ahead of them.
What you can do, and what to leave
You can
- Photograph any warning on the screen, with the kilometres showing.
- Check tyre pressures on a cold car, using the figures on the door pillar.
- Find the warranty document and the date the car was delivered.
Leave to the mechanic
- Anything on the high-voltage pack or its orange cables.
- Testing and replacing the low-voltage battery.
- Brake, suspension and wheel alignment work.
If it were our Tesla
We'd photograph the warning, work out which battery it's about and read the warranty before ringing anyone. If the big pack might be covered, we'd put it to Tesla in writing. For tyres, brakes and the small battery, we'd ask a local mechanic who sees EVs every week for a written estimate that names the fault and the parts.