4 min read
Battery Registration: Does Your BMW, Audi or Mercedes Need It?
Many European cars monitor the battery through a sensor and adjust charging as the battery ages. When a new battery goes in, the car has to be told — that is battery registration. Without it the car keeps charging the new battery as if it were the old, worn one, and may restrict start-stop and comfort functions.
On an older car, changing the battery is a mechanical job: old one out, new one in. On many newer cars it is also an electronic one. A small sensor on the battery terminal reports current, voltage and temperature to the car's energy management system, which keeps a running picture of how old the battery is.
Registration and coding are different things
Registration tells the car that a new battery of the same specification has been fitted, so it resets its ageing data. Coding changes the specification the car expects — needed if the new battery has a different capacity or technology from the one it replaces, such as moving from EFB to AGM.
| Registration | Coding | |
|---|---|---|
| When it is needed | Any battery change on a car that monitors its battery | When capacity or technology changes |
| What it does | Resets the car's battery-age data | Changes the battery specification stored in the car |
| Tool required | Diagnostic tool | Diagnostic tool with coding functions |
Which cars need it
Volkswagen Group cars — Audi, Volkswagen, Skoda, Porsche — with battery energy management ask for a BEM code at replacement: the battery's capacity, technology, manufacturer and serial number. BMW and Mini models with an intelligent battery sensor need the new battery registered, using a different procedure.
Other makes vary by model and year. Many recent Mercedes-Benz, Land Rover, Volvo and Ford models monitor the battery too. Rather than guess, send us the make, model and year and we tell you what your car needs before a technician sets off.
What happens if it is skipped
The car will start and drive. The problems come later: the charging strategy stays tuned for an aged battery, which can overcharge a new one, and the car may keep start-stop or some comfort functions switched off because it still believes the battery is weak. The new battery's life is shortened by the very system meant to protect it.
Cars that do not need it
Most Japanese and Korean cars without start-stop — and plenty of older European ones — need no registration at all. You may lose radio presets, the clock or one-touch window settings while the battery is disconnected, and those are reset by hand in a couple of minutes.
Common questions
Can I drive a BMW without registering the new battery?
The car will run, but it will charge the new battery as though it were the old one. Over months that shortens the battery's life, and some functions may stay restricted. Registration is part of doing the job properly.
Do Toyota and Nissan cars need battery registration?
Most do not. A like-for-like battery change on a conventional Toyota or Nissan is a mechanical job, with at most a few settings to reset afterwards.
How do I know if my car has a battery sensor?
Look at the negative terminal: a small module with a wiring plug attached to the clamp is the sensor. If the car has start-stop, it almost certainly has one.
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Sources
Last reviewed by the 800BATTERIES team.