1995 Mercedes Benz SL500 Testing battery & alternator

DANASAL

MEMBER
1995 MERCEDES BENZ SL500

Electrical problem
1995 Mercedes Benz SL500 V8 Four Wheel Drive Automatic

I drive my Merecedes mostly in the warmer months. During the winter I throw a caover over it and keep it in my driveway. I start it up every 6-7 days just to keep the parts moving. Recently I wnet to start it up and it was dead. I removed the battery, chraged it fully on a 12V fast charge and then re-installed it. The car started fine and the following morning it started OK, but after leaving it for 10 days in continuous cold weather the car was once again dead. I am trying to prove it the battery is bad or if the alternator is the culprit. The battery has a date of June '05 on it. I am not sure how old the alternator is or if is the original unit. What can I do on my own to prove out these two electrical components one way or the other?

regards,
Sal Ianniello
Staten Island, NY

2 Replies

GFIMOTORCARS

MECHANIC
673 POSTS

Sal I would recommend taking the battery to an auto parts store and having them load test it. If it fails the load test you need a battery. Since your vehicle sits a lot the battery is constantly draining and never really getting a full recharge. This will kill a battery overtime and is more than likely the case for your dead vehicle at this time. I would recommend when the vehicle has a new battery (or alternator which can also be tested at the autoparts store) start the vehicle once a week but leave it running for 30 - 45min. This will ensure that the alternator will have a chance to fully recharge the battery which should eliminate this from happening again.