Help Requested on an SL500 Mercedes

Question by OwnerSL500 posted 11 months ago in 2003-2012 (R230)

I purchased the car at auction during the summer of 2019.  I currently have 2 problems that no one can seem to answer.  Can you help?:

- The digital clock on the center of the dashboard does not keep accurate time.(runs too slowly).  Is there a way to correct this?

- The car has two batteries - the main battery under the hood and the auxiliary/support battery in the trunk.  I have 2 battery maintainers, one for each battery.  They both have quick disconnect plugs that attach directly to the terminal connectors on each battery.  The plugs have a 3 amp in line fuse.  The front battery maintainer seems to work fine, but the rear one is constantly blowing a fuse.  I've replaced the rear fuse numerous times, but no luck.  I don't drive the car during this time of year and recently, I attempted to start the car in my garage.  The engine(with the front battery maintainer) started fine.  However, there was a display feature which said "Convenience features are temporarily unavailable".  I believe it means that the rear battery is not charging, which would be correct, since it continually is blowing the in-line fuse.  What am I doing wrong?  What can I do to keep this battery charged during the winter months?

Thanks for any information you can provide.