BMW battery replacement at your curb, registration included

Why BMWs are different

Registration resets the car's record of battery age so it can adjust charging voltage as the battery ages. Coding is only needed when the type or capacity changes.

Where the battery is, and why it matters

On almost every BMW built in the last twenty years the battery lives in the trunk, on the passenger side, under the floor panel or behind a trim cover. What you find under the hood is a pair of remote jump terminals, which is why a lot of roadside jump attempts on BMWs fail: the driver connects to the terminals, sees nothing happen, and assumes the battery is not the problem.

The trunk location is also why a parts-store replacement often goes wrong. The battery has a vent tube that has to be connected so hydrogen from charging does not accumulate in the trunk. It has a hold-down bracket that needs a specific socket. On some models the intelligent battery sensor is clamped to the negative terminal and is easily damaged. And once the new battery is in, the car has no idea anything changed.

What registration does, and why it is not optional

BMWs use an intelligent charging system that adjusts the alternator's output based on the battery's age and state. As the battery gets older, the car raises the charging voltage to compensate. That is good for a tired battery. It is bad for a new one.

Put a new battery in without registering it and the car keeps charging on the old profile, at the higher voltage it had worked its way up to. The new battery is overcharged from day one, gasses more, ages faster, and typically fails in two to three years instead of five or six. The car may also throw charging-system faults, and on some models features start to switch off to save power because the car thinks the battery is still failing.

Registration is a command sent through the diagnostic port that tells the car a new battery is fitted and resets the age counter. It takes a few minutes with the right tool. We carry that tool, so it is part of the job rather than a reason to book a dealer visit afterwards.

Coding, AGM, and getting the capacity right

Registration and coding are not the same thing. Registration tells the car the battery is new. Coding tells it what the battery is.

If the replacement matches the original in capacity and type, an 80Ah AGM for an 80Ah AGM, registration alone is enough. If the capacity or type changes, the car has to be coded for the new specification or it will charge for the battery it thinks it has. This comes up more than you would expect, because previous owners put in whatever was cheap, and the sticker on the battery no longer matches what the car was built with.

We check what the car is coded for before ordering the battery, fit the matching spec, and code it if the previous replacement got it wrong.

Nearly every BMW from the late 2000s on uses an AGM battery, because start-stop and the amount of electronics in the car need it. A conventional flooded battery will physically fit, will be cheaper, and will be dead within a couple of years. We do not fit them to cars that were built for AGM.

Signs your BMW battery is going

The car tells you, but quietly. A message about increased battery discharge while stationary, often after the car has been sat a few days. Features switching themselves off: the seat heaters go, then the audio, sometimes the rear window defroster. A slow, laboured crank on a cold morning. iDrive rebooting or the clock resetting for no reason. Comfort access that stops working from the passenger side first.

Any of those on a battery over four years old is the battery. Any of those on a newer battery that was never registered is usually the battery too, for the reason above.

What the visit looks like

We come to the car with the correct battery, test the existing one and the charging system first, and confirm what the car is coded for. If it is the battery, it comes out, the tray and vent are checked, the new one goes in with the vent connected and the IBS sensor handled carefully, and the car gets registered and coded through the diagnostic port. We clear any stored charging faults and check that the car reports the new battery correctly.

Labor starts at $95. The battery is quoted by size and type for your model, and a genuine AGM in the right capacity is not the cheapest battery on the shelf, which we will tell you up front. Most swaps take under an hour including the electronics.

The same applies to Mercedes, Audi, VW, Mini and most other European makes, which use the same kind of battery management and the same registration requirement. Tell us the car and we will confirm before we come.

Queens, Brooklyn, Manhattan, and the rest of NYC

A BMW battery dies in a parking garage in Long Island City, on a driveway in Douglaston, on the street in Park Slope. We come to all of them, and the job gets done where the car sits rather than after a tow to a dealer and a two-day wait for a service slot. Text us the model and year and we will tell you what battery it takes and when we can be there.

Common questions