Warning: Battery acid is highly caustic. Protect your eyes, face, hands, clothing and the paintwork.
- Open the left-hand side case.
- Release the seat at the front and open.
![](https://motoinstruction.ru/img/bmw/21/127016.jpg)
- Release the fasteners (6) securing the battery tray (7) and remove the battery tray.
- Lift the battery off the holder together with the battery breather hose.
- Set the battery down on a level surface.
Battery acid — Density 1.28.
- Top up the battery acid to the "MAX" mark.
- Allow the battery to stand for at least an hour.
- Shake the battery slightly to allow the remaining air bubbles to escape.
- Top up with acid to the "MAX" mark if necessary.
- Recharge the battery or allow it to stand for 24 hours.
Charge current (amps) 10% of the nominal capacity (Ah).
- Check the acid level and, if necessary, top up with distilled water to the "MAX" mark.
- Replace the battery caps securely.
- Make a note of the charging date on the battery.
Caution: Only reconnect the battery with the ignition switched off to avoid short-circuiting. Connect the positive battery lead (+) first, close the protective cap over the positive battery terminal, then connect the negative battery lead (—). Make sure that the battery breather hose is not kinked or blocked. Battery acid is highly caustic. Do not permit escaping acid vapour to contact motorcycle components.
- Grease the battery terminals with acid-proof grease.
Acid-proof battery terminal grease — e.g. Bosch Ft 40 V1.
- Install the battery.
- Reconnect the two positive battery cables (5).
![](https://motoinstruction.ru/img/bmw/21/127017.jpg)
Caution: The motorcycle may only be ridden with the protective cap fitted on the positive battery terminal.
- Close the protective cap on the positive battery cable.
- Reconnect the negative battery cable.
- Install the battery tray.
- Guide the breather hose through the eyelet (see arrow) in the battery holder to the outside.
Note: Disconnecting the battery clears all entries (such as errors, adaptations) from the Motronic control unit memory. The loss of the adaptations may sometimes lead to engine performance being temporarily impaired when the engine is restarted. Motronic restores the lost adaptations itself over the following operating hours.
- Switch on the ignition.
- Fully open the throttle once or twice with the engine off. Motronic registers the throttle valve position.
Tightening torque:
Battery tray to battery holder — 4 Nm