Scope – Context

Ford hid the 12V battery for the 2016 C-Max Hybrid in the rear cargo area, not under the hood. This throws off a lot of people and leads them straight into YouTube hell. This guide is here to save your sanity.

Tools & Supplies

  • 10mm socket wrench
  • Ratchet extension (optional but helpful)
  • Flathead screwdriver
  • Replacement 12V AGM battery (Group 67R, e.g., Motorcraft BXT-67R or equivalent)
  • Gloves (optional)
  • Safety glasses (optional)

Step-by-Step Instructions

1. Power Down the Vehicle

  • Make sure the car is off and the key is removed.
  • Open the rear hatch.

2. Access the Battery

  • Remove the cargo floor panel by lifting it up.
  • Underneath, you'll find a foam storage tray—lift that out.
  • You’ll see the battery located in the spare tire well, near the right (passenger side) rear quarter panel.

3. Disconnect the Battery

⚠️ Always disconnect the negative (black) terminal first to avoid sparks.

  • Use the 10mm socket to loosen the negative terminal clamp and remove it from the post.
  • Then do the same for the positive (red) terminal.

You may need a flathead screwdriver to gently pry the clamps loose.

4. Remove the Battery Hold-Down

  • There’s a metal bracket holding the battery in place. Use your socket wrench to remove the bolt securing it.
  • Once removed, carefully lift the battery out. It’s heavy—around 30–40 lbs.

5. Install the New Battery

  • Place the new battery in the same orientation (positive and negative posts in the correct position).
  • Reattach the hold-down bracket and tighten it.
  • Connect the positive (red) terminal first, then the negative (black).
  • Make sure all connections are tight.

6. Reassemble

  • Replace the foam tray and cargo floor panel.
  • Close the hatch.
  • Start your vehicle to verify everything works. You might get a temporary reset of settings (radio, clock, etc.), but the hybrid system should come back online normally.

Common Issues

  • No crank after install? Double-check terminal tightness and polarity.
  • Weird hybrid errors? Give it a minute or two—hybrid systems sometimes need a “wake-up” cycle after a full power disconnect.
  • Radio or clock reset? Normal. You didn’t break anything.

See Also