A new-old-stock battery that was stored for years and doesn’t charge may have deeply discharged, causing it to appear dead. This can sometimes be revived with specific techniques, but success is not guaranteed. Here’s what you can do:

Why the Battery Isn’t Charging

  1. Deep Discharge State:

    • Lithium-ion batteries naturally lose charge over time. If they drop below a critical voltage, the battery management system (BMS) shuts them down for safety.

  2. Battery Age and Degradation:

    • Even unused, lithium-ion batteries degrade over time, especially if stored fully discharged or in poor conditions.

Steps to Try and Revive the Battery

1. Inspect the Battery and Connections

  • Ensure the battery is properly connected to the logic board.
  • Check for visible damage, corrosion, or loose connectors.

2. Reset the SMC

Since the SMC manages battery charging, resetting it might help:

  1. Shut down the MacBook.
  2. Disconnect the MagSafe adapter.
  3. On your 2011 MacBook Pro, press and hold Shift (Left) + Control (Left) + Option (Left) and the Power button for 10 seconds.
  4. Release all keys and reconnect the MagSafe adapter.
  5. Turn the MacBook on and check if the battery starts charging.

3. Leave It Plugged In

  • If the battery is in a deeply discharged state, it may take time to wake up:
    • Leave the MacBook connected to power for several hours.
    • The battery may slowly recover enough charge for the BMS to allow regular charging.

4. Try a Charge Cycle Reset

  1. Fully power down the MacBook.
  2. Plug in the charger and let it sit for 5-6 hours without turning on the MacBook.
  3. After this, turn on the MacBook and check for signs of charging.

5. Use a Battery Calibration Tool

  • Some external tools or third-party utilities (like CoconutBattery on macOS) can force the battery to attempt charging. These require specialized hardware or software.

6. Seek Professional Testing

  • A repair shop with a battery analyzer can check the health of the cells and determine if they are recoverable.

What If These Steps Don’t Work?

If the battery remains unresponsive, it’s likely the cells have degraded beyond repair, and the battery will need to be replaced. Even unused batteries stored improperly (e.g., in hot environments or fully depleted) can become permanently damaged over time.

Advice on Using the Original Swollen Battery

Continuing to use a swollen battery is risky:

  • It may expand further, damage internal components, or pose a fire hazard.
  • It’s recommended to replace it as soon as possible, even if it seems manageable now.

Let me know how it goes or if you’d like advice on obtaining another battery!