Mechanics

TESTING BATTERY & ALTERNATOR

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
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Danasal
February 9, 2009.



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.

Gfimotorcars
Apr 8, 2009.
The post advising to take it to an auto parts store is right on! But you can also check the alternator by charging the battery place it back in the car and then strat the car. With the car running remove the positive cable from the terminal of the battery. If the alternator is good the car will keep running, if it's bad, it will die. I would bet the battery is the culprit, it probaly needs replacing.

Good Luck,

Let me know how it works out!

Tiny
Jack Porter
Dec 21, 2009.