Mercedes-Benz S-Class Coupe 2015 Operator's Manual page 346

Battery (vehicle)
344
Benz vehicles and tested and approved by
Mercedes-Benz is available as an accessory.
It permits the charging of the battery in its
installed position. Contact an authorized
Mercedes-Benz Center for further informa-
tion and availability. Read the battery charg-
er's operating instructions before charging
the battery.
All vehicles except AMG vehicles: if the
indicator/warning lamps in the instrument
cluster do not light up at low temperatures, it
is very likely that the discharged battery has
frozen. In this case you may neither jump-
start the vehicle nor charge the battery. The
service life of a thawed-out battery may be
shorter. The starting characteristics can be
impaired, particularly at low temperatures.
Have the thawed-out battery checked at a
qualified specialist workshop.
AMG vehicles: at low temperatures, do not
charge a battery which has been removed
using a battery charger. Allow the battery to
warm up gently first, if necessary. Otherwise,
the service life can be shortened and the
starting characteristics impaired, especially
at low temperatures.