When Disconnecting and Connecting a 12 Volt Car Battery
When disconnecting a 12 volt automotive battery, remove the negative terminal first. Removing the ground terminal first, minimizes the possibility of shorting the positive terminal to metallic tools and under hood components.
When connecting a battery, connect the positive cable first. This helps to prevent damaging voltage spikes from back feeding through your electrical system.
In conclusion: Remove the ground cable first when removing a battery. Attach the ground cable last when installing a battery.
Always wear approved shielding to protect eyes, face and body when working near a battery.
Never expose a battery to flames or sparks. Batteries (especially when charging ) can form explosive hydrogen gas. Any ignition source could trigger a violent battery explosion.
Remove all jewelry before working around batteries. Jewelry worn on the hands can easily short between the positive battery terminal and metallic tools.
Note: This is not a comprehensive list of battery handling precautions. Consult with your vehicle and battery owners manual for additional safety guidelines.