"Battery Alternator Visit Workshop" - Any ideas?

[CBUser]

Hi,

I have an intermittent warning with my 2005 W203 C180 Kompressor (80k miles).

There seems to be no pattern to the warnings, but randomly while driving along open road, or while in stop/start traffic I get the "Battery Alternator Visit Workshop" error message pop up.

I've checked the battery voltage with the engine off in the morning before starting and it reads 12.3V~. With the engine on it will sit between 13.9 and 14.1V quite consistently (I've watched it using the built-in voltage monitor on the dash). It has no problems starting.

The battery surprisingly seems to be original (judging by the date stamp on terminal). I took it out and cleaned it up, checked all the connections and the water level but the error still pops up.
I know it's well past the normal life expectancy of a battery but all tests run on it say it's healthy and I'm reluctant to start randomly replacing parts. Also the error message pops up while the engine is running so I'm less inclined to suspect a weak battery and more suspicious of alternator/wiring.

The alternator was replaced by a previous owner and it appears he replaced the pulley and belt too since those parts look new. There's no strange noises from the belt or pulleys but I don't know what grade of parts were used. But it supplies 14V so I'm assuming all is well there?

My next step is to use Torque Pro to log the battery voltage while driving and see if there are any blips shown when the error pops up.

Does anyone have any ideas that could help pinpoint the issue?

 

[Petrol Pete]

The unit holding the brushes on to the alternator slip ring might be at fault. Its two screws and a plug to DIY replace and is available separate ( as opposed to a complete alternator) at a reasonable cost.

 

[grober]

RENEW THE BATTERY AS A MATTER OF COURSE

 

[Ted]

Agree with @Petrol Pete as a likely source of the problem, but given the age of the battery it has to be a suspect.
What tests have been done on it?

Also remember that the dash voltage monitor is software generated and unlikely to be as accurate as a decent quality dmm.

 

[CBUser]

The unit holding the brushes on to the alternator slip ring might be at fault. Its two screws and a plug to DIY replace and is available separate ( as opposed to a complete alternator) at a reasonable cost.

Thanks for this info. Do you have a name for that part I can search for?

I quite enjoy a good DIY.

 

[CBUser]

Agree with @Petrol Pete as a likely source of the problem, but given the age of the battery it has to be a suspect.
What tests have been done on it?

Also remember that the dash voltage monitor is software generated and unlikely to be as accurate as a decent quality dmm.

It holds above 12V even after a week sat idle. This was measured using a multimeter and I also spend a lot of time driving with the dash voltage monitor displayed.

I admit the idea of a hanging onto a 13 year old car battery is futile and if were struggling to start the car and not holding a good voltage I'd have got rid by now. I also have an old E46 diesel which is 16 years old and still on the original battery which starts the car first time even in the recent -5 dip we had.

If what Petrol Pete mentioned doesn't help I will get myself a new battery.

 

[Ted]

That isn’t a measure of the battery condition.
The best test is a load test (there are others) - It is unlikely to be the battery, but can’t be ruled out.

 

[CBUser]

The unit holding the brushes on to the alternator slip ring might be at fault. Its two screws and a plug to DIY replace and is available separate ( as opposed to a complete alternator) at a reasonable cost.

Is this the part you are referencing?

Alternator Regulator BOSCH F 00M 144 147 buy cheap online

Since it had the alternator replaced, wouldn't the new alternator come with one of these already fitted?

 

[HITECH]

Get this a lot on W03s. 1st port of call would be to charge ur battery up over night. I used to get it every 3 weeks when I worked offshore. After sitting for 3 weeks. It would come on n off for a few days. I charged it up when i got back 1 trip and it stayed off. If its original battery then maybe sounds like time to change it. Post some pictures of the top of your battery in here and the numbers on top of it and we can help you out with new battery and prices.

 

[CBUser]

Get this a lot on W03s. 1st port of call would be to charge ur battery up over night. I used to get it every 3 weeks when I worked offshore. After sitting for 3 weeks. It would come on n off for a few days. I charged it up when i got back 1 trip and it stayed off. If its original battery then maybe sounds like time to change it. Post some pictures of the top of your battery in here and the numbers on top of it and we can help you out with new battery and prices.

As luck would have it I took a photo of the battery when I removed it.



The stamp on the negative terminal is "22 05"

 

[grober]

Sounds like a momentary short or break in a main power circuit associated with car movement. Favourite would be the engine earth strap- usually between the bell housing and a chassis panel- can break inside the plastic insulation or corrode at the fastening either end. With battery that old I wonder if you have enough conducting material floating around in the electrolyte to cause momentary internal shorts reducing its internal resistance ?

 

[CBUser]

Sounds like a momentary short or break in a main power circuit associated with car movement. Favourite would be the engine earth strap- usually between the bell housing and a chassis panel- can break inside the plastic insulation or corrode at the fastening either end. With battery that old I wonder if you have enough conducting material floating around in the electrolyte to cause momentary internal shorts reducing its internal resistance ?

The engine earth strap is a good shout. Can I get to that earth strap from the top of the engine?

I did top up the distilled water in the battery when i removed it. It didn't need much extra to cover the electrodes and i couldnt see any debris. Was surprised how good condition the battery was in.

 

[grober]

Best bet for engine ground strap location is from looking from underneath. In older models it was often a braided strap- nowadays more like to be a thick black plastic coated cable- may be separate or bundled with other main engine cables .

 

[cheddar]

On the w203 models I’ve found the engine earth is often located underneath the transmission tunnel towards the rear of the gearbox on its own, a thick braided cable with no insulation.
Not a particularly common fault, but have seen it be loose before and well worth a look.
Failing that, an alternator issue.
I too cannot see your issue being caused by the battery but any reputable auto electrician should be able to load test the battery for free.

 

[CBUser]

The car has an MOT next week so I'll ask the tester to check for a loose earth strap on the engine/transmission and also if possible load test the battery.

I'll check all the accessible earth connections myself on the weekend.

 

[Petrol Pete]

Is this the part you are referencing?

Alternator Regulator BOSCH F 00M 144 147 buy cheap online

Since it had the alternator replaced, wouldn't the new alternator come with one of these already fitted?

you would expect a new alternator to have a new pick up in it , yes. Was the replaced alternator brand new ?

 

[CBUser]

you would expect a new alternator to have a new pick up in it , yes. Was the replaced alternator brand new ?

I'm not sure, will inspect the alternator and try get a part number off it on the weekend. The car only has 1 previous owner but the garage we bought it off said they fitted a new alternator. I fully expect it to be a generic auto factor part. Would be shocked if it's a Valeo or Bosch unit but it does seem to supply a good 14V.

 

[HITECH]

Did you give the battery an overnight charge then try it ? i have came across this a lot. Once it goes below a certain level. Until it is completely fully charged ( and the alternator will charge it to keep it running and everything but maybe just not that extra volt to kick the message off the dash) CHARGE YOUR BATTERY UP then run ur car then come back with results.

As luck would have it I took a photo of the battery when I removed it.

View attachment 83272

The stamp on the negative terminal is "22 05"

 

[GordonTarling]

If the battery really is 14 years old, it's time for a new one.

 

[190]

Battery voltage alone is not a test of condition so I would have it tested but even with a good battery 12.3 volts is only 50 % charged. Fully charged would be 12.6 volts minimum and 12.7 or little higher for modern batteries. 12.0 volts is almost fully discharged.