Electrics and batteries
A car that won’t start has at least six possible causes and only one of them is the battery. Fitting a battery to find out is an expensive way to guess — so we test the circuit first.
What the noise tells us before the bonnet is even up
| What happens | Usual suspects |
|---|---|
| Nothing at all, no dash lights | Flat battery, corroded terminal, or a main earth |
| One loud click | Starter solenoid, or a battery too weak to crank |
| Rapid clicking | Low voltage — often battery, sometimes alternator |
| Cranks but won’t fire | Fuel, spark or crank sensor — not a supply problem |
| Starts then cuts out | Immobiliser or fuel delivery |
| Battery light on while driving | Alternator or its belt — don’t switch the engine off far from home |
| Flat every Monday | Parasitic drain, or short journeys never recharging it |
What it costs
| Job | Price inc. VAT |
|---|---|
| Battery, starting and charging test | £69 |
| Battery supplied, fitted and coded | from £129 |
| Alternator | from £345 |
| Starter motor | from £315 |
| Parasitic drain trace, up to 2 hours | £139 |
| Earth strap or terminal repair | from £69 |
| Wiring repair, per section | quoted |
| Dash cam hard-wired | from £95 |
Test fee comes off the repair if we do the work.
A modern battery isn’t a drop-in part. Most cars from around 2012 need the new battery registered to the charging module. Skip that and the alternator carries on charging as if the old tired battery were still fitted, which quietly shortens the life of the new one.
We code it. Some places don’t, and that’s part of why a battery costs £129 here and £79 down the road.
We don’t fit aftermarket remote starters or alarms. Badly installed ones cause drains and immobiliser faults that are expensive to trace afterwards — and we’d be the ones tracing them.
Why does it keep going flat?
Battery at end of life, alternator not fully charging, or something drawing current with the car off. Testing tells you which — replacing on a guess helps in one case out of three.
How long should a battery last?
Four to six years. Short journeys cut that a lot, because the alternator never gets time to put back what starting used.
The car’s fine after a jump start. Is the battery bad?
Maybe — or the alternator isn’t replacing what the starter took. A jump only proves it runs with enough voltage; it says nothing about which part failed.
Warning light on the dash?
Worth a scan — and note that ABS, airbag, brake and engine management lights are MOT failures in their own right.