Battery terminal maintenance — corrosion and grease

The terminals are where the battery meets the car’s wiring. Corroded or loose ones can make starting hard even with a healthy battery. It’s one of the simplest and cheapest things worth looking after.

Where the deposit on the terminals comes from

A white, bluish or greenish deposit is the effect of corrosion, sped up by fumes from the battery and moisture. A layer of deposit increases the resistance of the connection, which worsens current flow — especially at the high draw during starting.

How to clean and protect the terminals

1. Disconnect the negative terminal first, then the positive
2. Remove the deposit with a wire brush or a special cloth
3. If needed, wash with a baking-soda solution
4. Dry, refit the terminals (positive first, then negative) and tighten
5. Protect with terminal grease or technical petroleum jelly

Symptoms of neglected terminals

• A heavy, uncertain start despite a good battery
• Flickering lights and “losing” power
• Visible deposit and corrosion around the poles
• Unusual electrical faults

Note: the same symptoms can come from a worn battery. If the problem returns after cleaning the terminals, check the battery’s condition.

Sometimes a “dead battery” is just neglected terminals — a few minutes of cleaning can bring the start back to life.

When replacing the battery with call-out we clean and protect the terminals, so the connection stays reliable all season.