Replacing a BMW battery: how it should go
Find out why it went flat
AA New Zealand says a flat battery should be followed by a diagnostic check for the cause. The alternator keeps a battery topped up; it isn't built to bring a dead one back, so a new battery on top of a charging fault won't last.
Match the type
If the car has start-stop, AA New Zealand says it needs an AGM battery, and another type impairs the fuel-saving system. Ask what type comes out and what type goes in.
Register it to the car
Where a battery management system is fitted, the new battery has to be registered with it. That takes diagnostic equipment, so ask before the job starts whether the mechanic will do it.
Get it on the invoice
The invoice should name the battery fitted and say it was registered. Keep it with the car's records.
Was your BMW sold new here, or imported?
Most used cars imported into New Zealand come from Japan, and Wikipedia notes that most of the non-Japanese makes among them are German, BMW included. So the BMW in your driveway may well have spent its first years in Japan.
That changes two things. The handbook is likely to be in Japanese, and the service history may not have come with the car. If there's no record, ask for the first service to be a thorough one, so you know where you stand.
It also changes the warranty. Driven reports BMW New Zealand has given its cars five years of warranty, with a 100,000 km limit, since 2014. When that cover began, BMW New Zealand said it was only available on cars bought from its New Zealand dealerships, so an import shouldn't be assumed to have it.
Servicing a BMW away from the dealer
If the car is still under BMW's warranty, the MTA says a qualified independent mechanic should be low risk as long as the servicing follows BMW's guidelines and specifications. A maker can still turn down a claim if the independent's own workmanship caused the fault.
Out of warranty, the choice is wide open. What matters is the equipment and the habit: a garage that sees BMWs every week will have the diagnostic gear, know the common jobs and be able to update the service record the car keeps. For more on European cars generally, see European car servicing.
Questions to ask before you hand over the keys
- Does your diagnostic equipment read BMWs, and can you update the car's service reminder?
- Will the new battery be the same type as the old one, and will you register it?
- Which oil and filters are going in, and do they match what BMW lists for this car?
- Will you ring me before doing anything that isn't on the quote?
- Can you check the VIN against current recalls?
What you can do, and what to leave
You can
- Note any warning message and photograph it before you switch off.
- Keep a battery charger on a car that sits unused for weeks, if the handbook allows it.
- Find the VIN on the registration papers so the mechanic can look up the exact model.
Leave to the mechanic
- Fitting and registering a replacement battery.
- Reading fault codes and resetting service reminders.
- The scheduled service, with the record updated.
What we'd do with a BMW
We'd check whether the car was sold new here and whether any BMW warranty is still running, because that decides how cautious to be about who services it. For a battery, we'd only say yes to a quote that includes finding why the old one died and registering the new one. For a service, we'd pick a mechanic with BMW diagnostic equipment and get the oil and parts named in writing.