[tomt]

The owner's manual just says:

Quote:

Charging the battery

Only charge the battery in the vehicle via
the terminals in the engine compartment
with the engine switched off, refer to
'Jump-starting', page 134 ff.

I haven't taken a volt meter to the Mini, nor to my AC battery charger, but car alternators regularly go to 14V to charge the battery. The usual problem when charging batteries is charging too fast which heats up the battery. With old style unsealed batteries, overcharging would break down some of the water into hydrogen and oxygen which explodes easily.

Perhaps more to the point, the owner's manual advises you have to reset other things:

Quote:

Power failure

After a temporary power failure,
a discharged battery, some of your
equipment will function only to
extent and must be reinitialized readjusted.
Individual settings are also
must be reprogrammed:
>Time:
Must be reset, refer to page 63
>Electric power windows:
Must be reinitialized, refer to
>Radio*:
The stations must be reset, refer
Owner's Manual for Radio
>Navigation system*:
It may take some time for its operability
to be restored, refer to the Owner's Manual
for Navigation System.

As Boyracer says, the engine computer will have reset, but the only way to deal with that is to drive the car.