Advice · updated 2026-10-03
Battery hold-down and terminals
The clamp stops the battery moving, and clean tight terminals keep the starting current flowing. A loose battery can crack its own case. We refit the clamp with the new battery.
Why the clamp matters
A battery that can shuffle in the tray hammers the case over potholes and speed humps. The case cracks at the corner, acid escapes, and the battery is finished. The hold-down, whether a clamp on the rim or a threaded rod on a bar, goes back on before the job is called done.
If the clamp is missing or the thread is rounded, say so on the quote. A new battery without a clamp is not an improvement. The fitter will not leave it loose because the old hardware was annoying.
Terminals, in the right order
Workshop practice is negative lead off first and positive lead off second. Positive goes back first, negative last. That order reduces the chance of a spanner bridging the positive post to the bodywork while the negative is still on.
Clamps should be clean and tight enough that they do not twist by hand. A monitoring sensor on the negative lead stays with that lead. It is not discarded so a plain clamp fits more easily. Spread or melted posts mean the lead may need attention, which the callback should know about.
Grease, covers and damaged posts
A light smear of terminal protector on a clean post slows corrosion. It does not fix a loose clamp, and it does not seal a cracked case. Plastic covers go back over the positive post so a stray tool cannot short it.
A cracked, leaking, swollen or frozen battery is not jumped to test the terminals. The fitter comes to the car in London, Birmingham or Manchester after you type your mobile number and we call you back. Running voltage is then checked, often about 13.8 to 14.7V, with smart charging able to sit lower once the battery is reported full.
Questions before you send a quote
Can you fit a battery if the clamp is broken?
Tell us on the quote. The battery has to be secured. A missing clamp is part of the plan, not a detail to skip.
Which terminal comes off first?
The negative lead. It goes back on last.
Do you do this at the car?
Yes. We'll come to the car in the three cities.
A worked example
The clamp on a Focus was missing and the case had split at the lower corner from movement. That battery is not jumped. The quote is a replacement with the clamp refitted, negative off first when the leads come apart, positive back on first when they go together. The split case leaves with the fitter on the supply-and-fit.
Safety
Do not bridge the terminals with a spanner. Take the negative lead off first. Do not jump a cracked, leaking, swollen or frozen battery.