W212 e250 cdi battery light/alternator

[Moonshine123]

How’s it going everyone hope you are all keeping well.

I have a 2011 e250 cdi, 2 weekends ago the battery light came on while driving through town, got her home parked it up. Started it a few hours later no battery light? So took it another spin and eventually 30miles or so later battery light came on again. Parked car up suspecting the alternator.

My battery is due replacing as a few off the colder mornings previous to the battery light coming on, it was sluggish too start. (Don’t worry this will be replaced with a new one along with alternator)

Another problem, before this all happened sometimes when the car was being driven and say I stopped at a shop, when I would come out and turn the key nothing would happen, take key out try again starts no problem. Do you think it’s a problem with electrics or could the starter need replacement now when I’m doing alternator?

Mechanic finally took a look at it today for me and tested the alternator says it seems fine?

My head is melted at the minute trying to get this car fixed, if the alternator seems fine is there any point pulling it out and getting it refurbished/buying a new one? If so is the alternator a big job too change on these as I’m ok with my hands, have worked on plenty of older cars I’ve owned and changed plenty of alternators and starters in my time, but if their is a lot of stripping involved I will leave it up too my mechanics as I don’t have a lot of spare time.

Thanks for replies

 

[optimusprime]

I would go along the lines of a new battery , and go from there .

 

[Tonygw]

I would go with a battery for now also. If the voltage on the battery is 14V or there abouts when the engine is running then the alternator is fine, you can get the battery load tested. but by the sounds of it, the battery has seen better days and the colder weather will make it worse, (batteries don't function as well in the cold)

My c class sometimes doesn't crank whe I turn the key, I found that If I just turned the key and released to start, then maybe once a week or every two weeks it would do this, If i turn the key and hold it, then its fine. I am guessing my battery is on its way out. After all its 6 nearly 7 years old which isn't bad for a battery. I know its on its way as my stop start function has "stopped functioning" and I had a new aux battery a while ago. So it only leaves the main battery as the issue.

If one morning it refuses to start I will change it, until then its starting fine it will stay that way.

CHeers

 

[Moonshine123]

Thanks for the replies folks.

I will try a new battery first and go from there.

Where is the aux battery in the w212? Would it be worthwhile changing it at the same time?