BMW E65 flat battery and power cutting out
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Why does my E65 not go to sleep overnight and drain the battery?
A single module is waking the car up or keeping it from going to sleep. You can find the fault by pulling fuses one at a time and watching when the resting current drops. One cause that was found was a faulty comfort access door handle.
Why do the E65's navigation, radio and trip computer shut off when the voltage drops?
When the battery voltage drops too low, the car switches off power and reports that the voltage is low. The iDrive display and navigation shut off first. A weak battery is a common cause, and replacing or charging the battery often fixes the problem.
What should I check before replacing the battery?
Check the battery cable connections and the ground. Also make sure the fuses in the fuse box are seated properly, because a loose fuse can black out the central display and cut out the radio and seat heating.