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Matt
Matt, Mechanical Engineer
Category: Mercedes
Satisfied Customers: 21626
Experience:  BEng hons Mech engineering, in auto industry 22 years
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I won a Mercedes c200 sport, I am having the battery warning

Resolved Question:

I won a Mercedes c200 sport, I am having the battery warning light come on, believe it is saying battery not charging, but the battery is fine. It will run, then after a few hours, engine will not start, is it the alternator or starter motor perhaps?
Thanks
Charlie
Submitted: 2 years ago.
Category: Mercedes
Expert:  Matt replied 2 years ago.
Hello

I'd 1st check that the alternator is actually charging the battery in the car by taking a battery voltage reading with the engine off then another with the engine running. The 2nd reading should be higher than the 1st and climbing steadily. And also check that the alternator is secure to the engine as this provides the ground for the charging circuit and make sure that the engine / gearbox earth strap is secure and the contacts are clean and bright. if the alternator appears not to be working - take it to a electrical specialist and ask them to test it as sometimes you can replace just the diode pack and this will repair the alternator without requiring replacement

And one last thing is – how old is the battery? – As even good quality ones need replacing every 5 years and faulty battery just won’t hold a charge

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