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12V Battery Issues on 2021 Polestar 2 - Replacement Tips?

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Mike T. · rep 0 · May 25, 5:24 AM · 1 replies · solved · Question

Vehicle: 2021 Polestar 2 Standard Range Single Motor

My 2021 Polestar 2 Standard Range Single Motor has been acting a bit strange lately. Sometimes it takes a couple of tries to "wake up" the car when I get in, and the infotainment system has rebooted unexpectedly a few times. I'm suspecting the 12V battery might be on its way out, even though it's an EV.

Where is the 12V battery located in the Polestar 2, and is replacing it a straightforward DIY job, or are there special considerations for EVs? Any specific battery type I should look for?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 25, 5:24 AM

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ClearTheCode admin answer:

Your suspicion about the 12V battery is likely correct. Even though your 2021 Polestar 2 is an electric vehicle, the 12V battery plays a critical role in powering all the low-voltage systems, including the infotainment, lights, door locks, and most importantly, the relays that 'wake up' the high voltage system. The symptoms you describe are classic signs of a failing 12V battery.

  1. Role of the 12V Battery in EVs: It acts as the primary power source for all auxiliary systems and is essential for 'booting up' the car's computers and enabling the high-voltage battery to engage. If it's weak, the car won't start or will exhibit electrical glitches.
  2. Location: In the Polestar 2, the 12V battery is typically located in the frunk (front trunk), under a cover. You'll need to remove a few fasteners and possibly a plastic tray to access it.
  3. Battery Type: The Polestar 2 uses an AGM (Absorbent Glass Mat) 12V battery. It's crucial to replace it with another AGM battery of the correct size and specifications (CCA - Cold Cranking Amps, and Ah - Amp-hours) to ensure compatibility with the vehicle's charging system and electrical demands. Avoid standard lead-acid batteries.
  4. DIY Considerations: Replacing the 12V battery can be a DIY job, but there are important considerations:
    • Safety: While not directly dealing with the high-voltage system, always disconnect the negative terminal first, then the positive, and reconnect in reverse (positive first, then negative) to prevent short circuits.
    • Vehicle Electronics: Modern vehicles are sensitive to power interruptions. Some owners use a memory saver tool to maintain power to the vehicle's computers during replacement, preventing loss of settings or potential error codes.
    • Battery Management System (BMS) Reset: After replacement, the car's Battery Management System might need to be 'told' that a new battery has been installed. This can sometimes be done by driving the car for a period, but in some cases, a diagnostic tool may be required to register the new battery.

When to See a Shop: If you're uncomfortable working with electrical systems, or if after replacement you experience persistent error messages (e.g., OBD code B1212 - Battery Voltage Low, or U0100 - Lost Communication with ECM/PCM), it's best to have a Polestar service center or qualified EV technician perform the replacement and any necessary BMS resets. They can also properly dispose of the old battery.

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