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Jerry, Master Mechanic
Category: BMW
Satisfied Customers: 17220
Experience:  ASE Master, 30+ years exp. former shop owner, diagnostics, driveability tech
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BMW 325i: Is there any way I can replace my 2006 325i battery

Customer Question

Is there any way I can replace my 2006 325i battery without taking it to the dealer. I can buy the battery for $90 - but there is this complicated black box on top of the battery covering the positive terminal. How do I remove that and replace with a new battery and not cause the fuse to short out? Also - is it possible to jump the car while I am replacing the battery to maintain all the settings on the electronics?
Submitted: 6 years ago.
Category: BMW
Expert:  Jerry replied 6 years ago.









Hello and welcome to Just, Super mechanic here. About your vehicle.

The best way to retain all of the presets is to use a jump box that plugs into the cigarette lighter.

Remove battery cover or open right luggage compartment trim panel


Loosen nut (1).

Disconnect battery negative lead (3) and secure at side.

Necessary preliminary tasks:
  • Remove flap in luggage compartment panel on right
  • Disconnect battery negative lead
  • Remove distribution box


Unlock positive terminal cover (1) and remove.


Detach vent (1) in direction of arrow.
Release nut (6) of safety battery terminal (2).

Detach safety battery terminal (2) towards top, lay to one side and secure.
Release threaded pin (5) and remove holder with battery crash element (4).
Fold back both bar fasteners (3) and pull battery towards rear out of associated fixture.
Lift out battery.

Jerry and 4 other BMW Specialists are ready to help you
Customer: replied 6 years ago.
I am still nervous about removing the battery. The dealer talked about the System recognizing the new battery. If I do not have a jump box - what will happen? As long as the car will run and the system work - I do not care if I lose the info I have stored.
Expert:  Jerry replied 6 years ago.
It's hard to say what would be the results of not using a jump box. I normally do, and a lot of the auto parts stores that sell batteries, (and install them for free) also do, to my knowledge. However, let me give you what I have about it.

Instructions for Disconnecting and Connecting Battery

12 00 ... - Instructions for disconnecting and connecting battery

Before disconnecting battery:
Turn off the ignition and other electrical loads/consumers to prevent sparking when reconnecting.

If the ignition is not turned off when the battery is disconnected, fault memories may be set in some control units.


  • There is a danger of mixing up battery leads: If the battery positive and negative leads are the same colour and you are in doubt, follow the polarity to the battery, then mark and cover the leads.
  • On vehicles with radio code: After disconnecting the battery, the radio code must be re-entered. Therefore obtain the radio code card from the customer beforehand. Note stored stations and restore them after connecting the battery.
  • Stored settings of the on-board computer and clock will also be lost.
  • All available central keys must be recoded for cars with first generation infrared transmitter locking systems.

General notes on disconnecting battery:

  • Do not disconnect battery leads and leads from alternator and starter motor while engine is running.
  • Cars with IBS on battery negative terminal: Do not under any circumstances pull/lever off pole shoes by force.

Do not under any circumstances release socket-head cap screw of IBS.

  • Detach terminal of battery negative lead from car battery and second battery if fitted. Cover battery negative terminal(s) and secure.
  • When work is carried out on the electrical system, faults may be caused in the fault memories of some control units when the battery is connected.
  • When installing battery terminal: Tightening torque 61 21 1AZ

After connecting battery:

The scope of application of some systems may be restricted after a power supply interruption.

Likewise, individual settings may be lost.
Settings or activations must be carried out, depending on the equipment specification.

  • Vehicles with automatic engine start-stop system (MSA): MSA function is active only after learning period (vehicle must not be woken for a period of approx. 6 hours) > if necessary, notify customer of the situation
  • E46 (AWD)/ E53/ E83: Carry out steering angle sensor adjustment
  • If necessary, carry out adjustment of active front steering
  • If necessary, activate sliding sunroof
  • If necessary, activate power windows
  • If necessary, activate mirror with compass

Vehicles with a two-battery system

Receiving/giving starting assistance via jump start terminal

The engine can be jump-started with an external voltage supply via the jump start terminal on the right side of the engine compartment.

The starter battery is isolated from the alternators when the engine hood/bonnet is open.

Giving starting assistance via the jump start terminal is thus limited by the capacity of the starter battery when the engine hood/bonnet is open.

Charging starter and equipment batteries via jump start terminal
The starter battery is charged as a matter of priority with a charger connected to the jump start terminal. The voltage at the starter battery is the decisive factor in determining whether the equipment battery is also included in the charging operation. The supplementary control unit automatically detects a charging operation at a charging voltage at the starter battery of >=13.5 V. The isolating relay is closed and thus the equipment battery is connected in parallel. Both batteries are now charged.

  • Terminal 61 inactive
  • Terminal 15 inactive
If terminal 15 becomes "active" during the charging operation, the isolating relay is opened immediately and again only the starter battery is charged.

When the engine hood is open, the isolating relay is also opened in normal operation when the engine is running.
A special mode can be set by means of diagnosis for workshop/garage operation. The isolating relay is closed from terminal R in this operating mode. This mode is automatically reset once a distance of 5 km has been driven.

Trickle charging

The increased closed-circuit current consumption can be compensated for via the jump-start connection point with the aid of the "Acctiva easy" battery trickle charger (Service Information 2 03 05 205).

The cigarette lighter is isolated from the electrical system after terminal R "OFF" on a timed basis (60 mins.), thereby interrupting charging of the equipment battery via the cigarette lighter. This is prevented if the battery master switch (on the right side of the luggage compartment behind the panel) is turned on and off again twice within 2 seconds. (Cigarette light battery charging function).