Battery/Alternator problem

[codemonky]

I have a 2002 C200K sports Coupe (Evo Panarama)and recently keep getting the battery/alternator light flashing on and off. My garage cannot find a problem. Today it came on for quite a while then changed the message to 'undercharge consumer defective'. Any information on this please.

 

[panason1c]

I'm assuming the obvious and going for the alternator on its way out?.........the message you get comes on when there is an undervoltage situation.

 

[jberks]

Could be low voltage - but that is more of a question than an answer as low voltage could be caused by simply running short distances with your lights on, a weak alternator, a failed battery controlled unit, or a current leak. If you suspect that short distances are the issue, pop it on a trickle charger overnight. Otherwise, start by checking the voltages at the battery when stood and running. Then you need to strap and ammeter across the battery and leave the car stood for an hour, checking the current draw over that period. Some drains do not fire up for 30 minutes believe it or not, so a cursory 5 min check may not find a problem.

 

[jibcl500]

You need to see what the running voltage is, pop into ATS or kwik fit and ask for them to check it, could just be the regulator pack on the back of the alternator £30 roughly from a Bosch service center and 30 mins to fit, MB will only sell a complete alternator for about £400 ++

jib

 

[wireman]

I guess its the brushes worn down.
Go for a brush pack from a trade auto electrical outlet about £10+vat, make sure the contact inside the alternator is clean before you fit the new one.

 

[jberks]

I guess its the brushes worn down.
Go for a brush pack from a trade auto electrical outlet about £10+vat, make sure the contact inside the alternator is clean before you fit the new one.

A 2002 200k with a worn out alternator? Surely not. I wouldn't expect that issue for another 10 years/150k. (I assume it's not a lunar orbiter?) Far more likely to be an electronics issue or just an undercharged battery.

 

[Aviator]

Connect a meter across the battery terminals rev up the engine, battery voltage should rise to about 14.5 volts this indicates the alternator is charging if the voltage is low I agree try a bush pack .

 

[alec2]

If you are on the original battery it could be on the way out (5 years). How many miles has car done.

Try to check voltages using a digital meter

Test1 Measure voltage at fast tickover on low or no load. Should be about 14 v. Lower than 13.5 needs investigation. Probably alternator related.

Test2 Measure voltage after car has been standing for a hour unused, no loads on. Should be idealy 12.6. lower than 12.5 is suspect. Possibly battery on way out.

Alec

 

[codemonky]

Mileage

The mileage on the C200k is at this time 42,300 and I have to say I was quite surprised at getting the messages.

 

[brandwooddixon]

One other possibility is that your poly-v belt is slipping.

If it is you'll probably notice a drop in power assistance on the steering whenever the low charging light comes on.

 

[jberks]

I'm going for either a poorly battery (5 years is a possibility though a tad premature) or a current drain issue. This seems to be by far the most common causes of low battery warnings on cars of this era. I've seen loads of posts on here that come down to a drain issue and we recently had to replace the switch bar on our 2003 E class that turned out to be draining the battery.
I'd be very surprised if its the alternator or belt.

 

[CMR]

Is anything electrical not working as it should? (i.e. a consumer defective?)

I had issue with my w203 at 19,000miles with 'undervoltage switch off consumers' red warning that kept coming on which was down to a faulty alternator and reg pack which meant the battery was not charging, however I have seen 'consumer defective' in this thread link Be careful if you fit a new battery though not to blow rear SAM.

 

[E270]

I've just had a problem just like that on my E270 first it showed me "1 malfunction electrical consumers switched off". The car does this to same battery power.
Then I got "2 malfunction BATTERY/ALTERNATOR" in red
And " VISIT WORKSHOP"
Then is get scary because the brake assistant switches off and your braking distance increase. I would advise anyone never ever try driving the vehicle when this happenes.
I took it to the garage done a simply battery and alternator check and told me its the alternator.
Replaced it with a reconditioned one cost me all in £150
It's all sorted.

 

[AnthUK]

Had exact prob on my E320cdi and Merc dealer replaced regulator pack. Would very much doubt complete alternator needs replacing.

 

[television]

I've just had a problem just like that on my E270 first it showed me "1 malfunction electrical consumers switched off". The car does this to same battery power.
Then I got "2 malfunction BATTERY/ALTERNATOR" in red
And " VISIT WORKSHOP"
Then is get scary because the brake assistant switches off and your braking distance increase. I would advise anyone never ever try driving the vehicle when this happenes.
I took it to the garage done a simply battery and alternator check and told me its the alternator.
Replaced it with a reconditioned one cost me all in £150
It's all sorted.

You cant complain at that price what ever they did, it often pays to go to a Bosch service center as they are much cheaper than MB, and better on electrics