mechanics.trade
Car battery replacement
A car battery starts the engine and steadies the electrics while it runs.
What battery replacement means
Most last between three and six years. Cars with stop-start use a heavier duty battery, usually AGM or EFB, and many need the new one registered to the car so the charging system treats it correctly.
What the job covers
- Battery testing under load
- Supply and fit with correct specification
- Start-stop AGM and EFB batteries
- Battery coding to the vehicle
- Charging system and alternator check
When you might need it
- The engine turns over slowly, especially on a cold morning.
- Stop-start has quietly stopped working, which is often the first sign the battery is tiring.
- The car needs a jump start after standing for a few days.
What it costs, and what changes the price
Typically £90 to £250.
- Size and type. A stop-start AGM battery costs noticeably more than a conventional one.
- Some cars need the battery coding to the car, which adds a little labour.
- Batteries buried under a seat or in the boot take longer to reach than ones under the bonnet.
How long it takes
Usually under half an hour, including a charging system check.
Common questions
How long should a battery last?
Three to six years is typical. Short journeys shorten its life, because the alternator never gets long enough to put back what starting took out.
Can I fit a cheaper standard battery to a stop-start car?
It will start the car, but it is not built for the charge cycling stop-start does and will not last. Most garages will fit the correct type.
Why does my new battery keep going flat?
Usually something is drawing power with the car off, or the alternator is not charging properly. Both are measurable.