You can trickle charge the battery and get a bit more service.

Being a four year old battery though, I would consider eventual replacement. If there is any problem with the battery (dead cell, etc.), your alternator will have to work harder...

__________________
2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car