Disconnect the negative battery terminal

Removing the negative cable from the battery physically isolates it from the car's electrical system, stopping parasitic drain from clocks, alarms, and onboard computers. This is a simple, zero-cost way to slow discharge during storage.

Steps

1. Locate the battery and identify the negative (-) terminal.
2. Using a wrench (typically 10 mm), loosen the nut on the negative terminal clamp.
3. Lift the clamp off the post and tuck the cable aside so it cannot accidentally contact the terminal.
4. When ready to drive again, reconnect the negative clamp and tighten the nut.

Tips

• Always disconnect the negative terminal first to avoid short-circuit risk. Do not remove the positive cable unless performing other maintenance.
• Expect to reset the clock, radio presets, and some ECU-learned settings upon reconnection.
• Self-discharge still occurs at roughly 1-2% per month even when disconnected, so this method is best for storage up to about 3 months. For longer periods, pair with a maintainer.