Go Time Auto Repair

EV 12V battery testing and replacement

A dead EV with a full charge is almost always the small 12V battery, and we can have you back on the road in under an hour. Every EV has two batteries: the big one that moves the car and a small one that runs the computers, locks and screens and wakes the big one up. When the small one fails, nothing works, and Miami heat makes it fail early.

Book 12V battery (786) 884-4889
Typical time in the bay
under an hour, including the test and any reset the car needs.
How the price works
In writing, first
What we do

EV 12V battery

  • Test the 12V (or 16V on some newer models) battery under load, not just its resting voltage
  • Check the DC-to-DC converter that keeps the small battery charged from the big one, since a bad converter kills new batteries too
  • Replace the battery with the correct type: lead-acid, AGM or lithium, depending on what the car was built with
  • Reset or register the new battery when the car requires it, so warnings clear and charging is correct
  • Keep the car's computers powered during the swap so you do not lose settings
  • Check the factory warranty first, because many 12V failures happen while the car is still covered
  • Clear stored fault codes caused by the low voltage
Signs you need this

Signs you need this

  • The car will not wake up, unlock or go into drive even though the main battery shows charge
  • The screen is black or reboots on its own
  • A message warns that the 12V or low-voltage battery needs service
  • Random warning lights appear and disappear
  • The doors unlock slowly or the key is not recognized
How the price works

We check your factory warranty before anything else, since a 12V battery on a newer EV is often covered. If it is on you, we give you a written price for the battery and the swap before we start. Tax is on the part only. You choose the warranty length on the work: 90 days, 1 year or 2 years.

Questions people ask

Why does an electric car even have a 12V battery?
The high-voltage battery is too powerful to run small things like lights, locks, screens and computers safely, so the car uses a normal 12V system for them. The 12V battery also wakes up the big battery when you get in. No 12V, no wake up.
Does the big battery charge the small one?
Yes, through a converter. If the converter fails, the 12V battery drains even when the car has plenty of range. That is why we test the converter and not just the battery.
How long does a 12V battery last in Miami?
Shorter than the national average. Heat is the main thing that wears out a 12V battery, and ours sit in it all year. Many EV owners here see the first replacement earlier than they expected.
Can I jump start an EV?
You can usually jump the 12V system to wake the car, but never try to jump another car from an EV. Follow the owner's manual for the jump points. If it needed a jump once, it needs a test.
Will the warning light go away after you replace it?
Yes. We clear the low-voltage codes and, where the car requires it, register the new battery so the charging system treats it correctly.

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Ready to book?

Pick a time. We text you the written price before any work starts.

Book 12V battery(786) 884-4889