I am going away for three weeks and would like to know the best way to trickle charge my 2007 Mercedes CL600.
Three weeks is not that long. Technically if your Mercedes does not have any issues and a good battery, it should start right up in three weeks.
Still setting up a battery trickle charger is a great idea.
If it was my car I would get a battery maintanier that provides around 2 to 6 Amps and connect it to the jump starting terminal located in the engine bay.
The positive is covered with a red cap. The negative is a coper post but you can use any bare metal on your car.
This will be more than enough to keep your Mercedes battery in top shape.
Thank you very much for your reply. Just to clarify do I only apply the trickle charger to the starter battery under the hood?
Yes, your main concern should be the starting battery.
When you get back connect the auxiliary battery to the charger for a few hours as well. Next to the main battery should be a plastic cover. If you remove that, there should be a brass pin which is the positive terminal for the auxiliary battery. That's how it is setup on the W221 and I think the CL should be the same.