Battery fitting
Stop-start battery replacement
A stop-start car needs an EFB or an AGM, not a basic flooded battery. Fit the wrong one and the system starts to complain. We'll match it at the car in London, Birmingham or Manchester.
Is this postcode in the fitting area?
What the system asks of the battery
Stop-start switches the engine off when the car is stationary and starts it again as you pull away. Each cycle takes current from the battery and puts charge back later. A basic flooded battery is built for starting and a quiet life after that. It is the wrong unit for this duty.
Entry systems are often on EFB. Heavier systems, and many cars that also recover energy on the overrun, are on AGM. The old label, or the vehicle data, decides. An EFB may be upgraded to AGM. An AGM must not be downgraded. That is the whole selection rule.
The sensor on the earth lead
A lot of these cars carry a battery monitoring sensor on the negative terminal. It watches current, and the car uses that history to decide when stop-start may operate. The sensor stays with the lead. It is not twisted off and left dangling, and it is not replaced by a universal clamp for the sake of speed.
Registration tells that system a new battery is fitted. Battery registration is commonly required on Volkswagen Group and many BMW and Mini models, and it varies on other marques. Skip it, and the car can keep charging as if the aged battery were still in the tray. Stop-start may stay disabled even though the new unit is sound.
Checks during the replacement
The fitter comes to the parked car and reads resting voltage. Around 12.6V is the resting figure for a healthy 12V battery. A stop-start battery can be tired from short trips long before it fails to crank, because the cycling is harder than the starter motor alone.
With the engine running, charging voltage is often about 13.8 to 14.7V, but smart charging can sit lower once the battery is reported full. The alternator is not a bulk charger. Do not jump a cracked, leaking, swollen or frozen battery to get the car to a driveway. Call the condition out on the quote form instead.
After the wrong battery has already been fitted
If a flooded battery is already in a stop-start car, the repair is to fit EFB or AGM as specified and to register it when required. Clearing a warning without changing the type leaves the same fault. The car may still start. The system it was built with does not.
Cover is London, Birmingham and Manchester, at the vehicle. Type your mobile number on the quote form, name the car, and say if stop-start has stopped working. We call you back. There is no fixed price and no depot.
| Point | Flooded | EFB | AGM |
|---|---|---|---|
| Stop-start use | Not specified for it | Entry stop-start | Heavier stop-start and energy recovery |
| If this is what the car has | Leave it only on non-stop-start cars | Replace with EFB or upgrade to AGM | Replace with AGM only |
| Wrong substitute | Fitting this to EFB or AGM cars | Fitting this to an AGM car | None: do not step down |
| Likely result of the wrong type | Stop-start unavailable | Stop-start unavailable on an AGM car | Correct when specified |
Questions before you send a quote
My stop-start no longer works. Is it the battery?
Often the battery type or an unregistered new battery. The callback uses your registration and the old label to separate those cases.
Will a basic battery do if the car still starts?
No. Stop-start cars need EFB or AGM as specified. A flooded battery is the wrong part.
Do you register it?
Yes, when that model needs registration. It is common on Volkswagen Group and many BMW and Mini cars.
How do I request the visit?
Quote form, mobile number, then a callback. The fitter comes to the car in London, Birmingham or Manchester.