Aston Martin DB 9 2010 Manual page 235

Battery Conditioner
Warning: Do not attempt to start the vehicle with the battery
conditioner connected to the mains supply.
Warning: Do not smoke. Prevent flames and sparks.
Explosive gasses are given off by batteries during charging.
The battery conditioner is designed for conditioning of
partially or fully charged batteries. It will not effectively charge a
discharged battery.
For indoor use only. Disconnect mains supply before making
or breaking battery connections.
Do not leave the vehicle key in the trunk. If the trunk is closed
there will be no access to the contents of the trunk.
The battery conditioner supplied with the vehicle is suitable for
use on all types of 12 volt lead acid batteries.
If this vehicle is not going to be used for a period of time, and mains
power is available, use the battery conditioner to maintain the
battery charge level.
When connected the battery conditioner will maintain a small trickle
charge to keep the battery in a fully charged state. The battery
conditioner may be left in this state indefinitely.
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