C350CDI battery/ alternator/ something else

[Dankewell]

Hi there,
Hope someone can help me, 6 weeks ago the car broke down with a battery light coming up I charged the battery and the car started. I checked the onboard "secret" computer for the voltage and it confirmed that the alternator wasnt charging the battery so I had that replaced, after 1 day the dreaded battery light came on again, I have to add if I turn the car off and on again it normally sorts the problem sometimes it comes up again but it's not causing any breakdowns yet, well not physically anyway!! So I went on holiday foe a week and came back and the car was completely dead so I assumed the battery was gone so I brought a new 1. Car started fine volts were good so I thought great all sorted........ nope wrong 2 days later its back. I have it booked in to get looked at and the preceding day before the issue hadn't come up, so I cancelled. The car has been ok for nearly 3 weeks and the battery light came o again this morning. Please can someone help me as the garages I speak too either havent a clue and get worried when they speak to someone who actually knows a few things about a car or they're trying to tell me I need a new alternator for the best part of £700, surely this cant be the case

 

[mersum1es]

How much altenator vharge voltage is? Is there current draw when car is not running?

 

[Dankewell]

When the car is off the battery is at 12.5 when running it's up to about 14.2 but it does sometimes fluctuate down to around 12.8

 

[W1ghty]

When the car is off the battery is at 12.5 when running it's up to about 14.2 but it does sometimes fluctuate down to around 12.8

Where do you live so someone can recommend an MB specialist who knows what they are doing ?

 

[Dankewell]

I live near Croydon south London, I've tried a fewMB specialist but they're either too busy, like havent got any appointments for months or never get back to me

 

[mersum1es]

Sounds like bad voltage regulator or bad contact/earth somewhere.

 

[vijilants]

Try Merc Repairs in Hastings Rd, Croydon....020 8406 7866.

A good auto electrician should be able to pin this down.

Also word of advice re alternator replacement. More often than not, it is the rectifier pack within the alternator that fails when there is no output from the alternator. You do not need to replace the entire alternator as the component is a replacement part within the back cover of the alternator and is available at a fraction of the cost of the entire alternator and is available from the Main Dealer.

Many people fall it to the expensive trap of buying the entire alternator when this does not have to be the case.

 

[Dankewell]

Try Merc Repairs in Hastings Rd, Croydon....020 8406 7866.

A good auto electrician should be able to pin this down.

Also word of advice re alternator replacement. More often than not, it is the rectifier pack within the alternator that fails when there is no output from the alternator. You do not need to replace the entire alternator as the component is a replacement part within the back cover of the alternator and is available at a fraction of the cost of the entire alternator and is available from the Main Dealer.

Many people fall it to the expensive trap of buying the entire alternator when this does not have to be the case.

Thanks for the advice much appreciated I'll give the merc place on hastings road a call