Locate the battery. It is in the boot
Lift out the emergency jack and it can be seen beneath
Check the Negative (-) terminal clamp is tight
Check the Positive (+) terminal clamp is tight. CAUTION If using a spanner to tighten terminal, be careful not to short it on the bodywork
The battery retaining clamp position
To tighten, a 13mm socket is needed. Not too tight because you may damage the battery casing - replace the battery cover
Find a Haynes product for your BMW:
Search by registration mark
Search by make & model