Bad battery or alternator?
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2004 CLK320
Bad battery or alternator?
I had a scary experience with my car today. My car is a 2004 CLK320 and the battery is 5 years old.
I started the car when I left the office. I had a malfunction "Visit Workshop" with a picture of a battery. The car drove OK so i went to the store. After the store, I could not start the car. After a few trials, the car finally started. I rushed home and there was a lot of traffic. The gas pedal was not too responsive and ABS and ESP malfunctions came on. There was no headlight, the dash went dim and I could not even wind down my windows. At one point, even with the gas pedal fully depressed, the car would not go faster than 15 kmh.
All of a sudden, everything came back to life. The headlights came back on and the gas pedal was responsive again. I drove for another 20km and arrived home safely. I restarted the car, it went OK and I still have the same "Visit Workshop" message.
I hooked up my battery charger and the display said my battery was less than 50%. I will charge the battery for the next few hours.
Now I have to figure out if the culprit is battery or the charging system. Any comments?
I started the car when I left the office. I had a malfunction "Visit Workshop" with a picture of a battery. The car drove OK so i went to the store. After the store, I could not start the car. After a few trials, the car finally started. I rushed home and there was a lot of traffic. The gas pedal was not too responsive and ABS and ESP malfunctions came on. There was no headlight, the dash went dim and I could not even wind down my windows. At one point, even with the gas pedal fully depressed, the car would not go faster than 15 kmh.
All of a sudden, everything came back to life. The headlights came back on and the gas pedal was responsive again. I drove for another 20km and arrived home safely. I restarted the car, it went OK and I still have the same "Visit Workshop" message.
I hooked up my battery charger and the display said my battery was less than 50%. I will charge the battery for the next few hours.
Now I have to figure out if the culprit is battery or the charging system. Any comments?
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2004 CLK320
An update.
After charging for almost 3 hours, the battery was 90% full. Put the key in ignition and went to dyno mode. The voltage was 13.1v-13.1v. I started the car, the voltage went to 12.4v to 12.6v. The "Visit Workshop" malfunction came up again. I started the car twice and the results were consistent. I hooked up the battery charger and the battery is now below 50%.
Based on some readings on this forum, the voltage after started the car should be 14v. Does this mean that the alternator is toast?
After charging for almost 3 hours, the battery was 90% full. Put the key in ignition and went to dyno mode. The voltage was 13.1v-13.1v. I started the car, the voltage went to 12.4v to 12.6v. The "Visit Workshop" malfunction came up again. I started the car twice and the results were consistent. I hooked up the battery charger and the battery is now below 50%.
Based on some readings on this forum, the voltage after started the car should be 14v. Does this mean that the alternator is toast?
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MBWorld Fanatic!
Joined: Jan 2004
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2004 CLK320
Using the a battery charger, the battery did charge. Doesn't this mean that the battery is okay?
One thing strange was when everything went south (non-responsive gas legal, no power windows, no headlights, no dash, etc), it recovered all of a sudden.
After the battery charger, after starting to car, it would go from 13.2v to 12.4-12.6v.I let it run for 2-3 minutes, the voltage would not go beyond 12.6v. Since the correct voltage should be over 14v, this shows that it is a bad alternator, right?
Another possible culprit is the voltage regulator.
One thing strange was when everything went south (non-responsive gas legal, no power windows, no headlights, no dash, etc), it recovered all of a sudden.
After the battery charger, after starting to car, it would go from 13.2v to 12.4-12.6v.I let it run for 2-3 minutes, the voltage would not go beyond 12.6v. Since the correct voltage should be over 14v, this shows that it is a bad alternator, right?
Another possible culprit is the voltage regulator.
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Joined: Aug 2007
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CLS550
Sounds like your battery has a bad cell that is acting up sometimes. When it misbehaves, voltage drops too much and everything goes haywire. When it works, all is well for a bit, until the cell acts up again.
It has happenned to me before on a different MB. Just because the battery charges up does not mean that the battery is good. "Visit Workshop" is pretty much a sign that the battery is toast.
It doesn't sound to me that it's the alternator, but that's a guess. I would replace the battery first. Much easier and costs less.
It has happenned to me before on a different MB. Just because the battery charges up does not mean that the battery is good. "Visit Workshop" is pretty much a sign that the battery is toast.
It doesn't sound to me that it's the alternator, but that's a guess. I would replace the battery first. Much easier and costs less.
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2004 CLK320
Just got it fixed. The culprit was the alternator.
I went to my indie this morning and he tested and determined that the alternator was not charging the battery. He ordered a reconditioned alternator (Bosch AL0787X) and surprisingly, the parts arrived in about 15 minutes. He replaced the alternator and the whole job took maybe 1 hr 15 minutes. He charged me $524CAN for the job (parts + labour + tax). The alternator carries a 2-year warranty.
I went to a few places afterward. I monitored the battery voltage and it was 14.1-14.4v consistently while driving. It would drop 0.6v when rear defrost was turned on. It would drop another 0.6v when I turned on the ventilation fan full blast. The new alternator seems to be working fine. Just in case, I will carry my jumper cable in my trunk in the next few days.
I know that Autohausaz sells the same reconditioned alternator for $190US. I also found a Canadian online store who sells it for $240CAN. I could not wait because this is my daily commute. Also, it's more work because I would have to return the old part.
I have decided not to charge the battery overnight as suggested by the indie. If my car will start tomorrow, my alternator/battery are okay.
I went to my indie this morning and he tested and determined that the alternator was not charging the battery. He ordered a reconditioned alternator (Bosch AL0787X) and surprisingly, the parts arrived in about 15 minutes. He replaced the alternator and the whole job took maybe 1 hr 15 minutes. He charged me $524CAN for the job (parts + labour + tax). The alternator carries a 2-year warranty.
I went to a few places afterward. I monitored the battery voltage and it was 14.1-14.4v consistently while driving. It would drop 0.6v when rear defrost was turned on. It would drop another 0.6v when I turned on the ventilation fan full blast. The new alternator seems to be working fine. Just in case, I will carry my jumper cable in my trunk in the next few days.
I know that Autohausaz sells the same reconditioned alternator for $190US. I also found a Canadian online store who sells it for $240CAN. I could not wait because this is my daily commute. Also, it's more work because I would have to return the old part.
I have decided not to charge the battery overnight as suggested by the indie. If my car will start tomorrow, my alternator/battery are okay.
Last edited by mis3; Dec 4, 2013 at 10:30 PM.
