C230 Sportcoupe 2002 two batteries in two days
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Joined: Aug 2008
Posts: 31
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GLC300
C230 Sportcoupe 2002 two batteries in two days
Hello friends,
Two days ago my 5 year old battery did nit want to give the starter any juice,
Thinking nothing of it, I paid the fee and got a new one, same exact model, aftermarket.
This morning - bam, same deal, after it ran fine yesterday going to Walmart.
Boosted, it started. I took it for a short drive, let her sit for a few hours, started again.
Charging voltage is around 3.6V. Off voltage below 12V, about 11.7
Did I get a dud?
I will try to check for drain with an amp meter by pulling fuses, but I was wondering if anyone has some insight, being that it's 15 years old.
Thank you
Two days ago my 5 year old battery did nit want to give the starter any juice,
Thinking nothing of it, I paid the fee and got a new one, same exact model, aftermarket.
This morning - bam, same deal, after it ran fine yesterday going to Walmart.
Boosted, it started. I took it for a short drive, let her sit for a few hours, started again.
Charging voltage is around 3.6V. Off voltage below 12V, about 11.7
Did I get a dud?
I will try to check for drain with an amp meter by pulling fuses, but I was wondering if anyone has some insight, being that it's 15 years old.
Thank you
Super Member
Joined: Oct 2013
Posts: 527
Likes: 20
From: Carolinas
2005 C230K SS
3.6V charging? Guess that's a typo. My battery sits at about 12.6V with the car off even after a week....make sure you have the correct amp/hr rating, these cars have lots of consumers running off the battery.
Also, with the car running mine charges at 14.1V...maybe you have a bad alternator/VR
Also, with the car running mine charges at 14.1V...maybe you have a bad alternator/VR
Thread Starter
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Joined: Aug 2008
Posts: 31
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GLC300
Ah crap, and I proof-read it too....
13.6V charging, not 3.6, sorry about that and thank you for replying.
I just checked and the voltage dropped to 7.8V in a few hours.
So either the new battery won't hold a charge (not very likely) or I have something draining it.
This is the right battery, sized for the car, not some phony baloney hack.
Looks like every 5 years, like a clock, this car needed a new battery, but this time there's more to the story.
The voltage regulator ensures that the alternator does not supply too much voltage, right?
Not much more than that, I think.
I will try to follow a post to troubleshoot:
- let the car sit for half hour after the battery is fully charged, so that all the *** computers do their job
- measure amperage draw as fuses are pulled out one by one
- find which device/circuit drains it.
Looks like idle consumption should not exceed 70-100mA.
I will post results, but feel free to comment.
Thank you
13.6V charging, not 3.6, sorry about that and thank you for replying.
I just checked and the voltage dropped to 7.8V in a few hours.
So either the new battery won't hold a charge (not very likely) or I have something draining it.
This is the right battery, sized for the car, not some phony baloney hack.
Looks like every 5 years, like a clock, this car needed a new battery, but this time there's more to the story.
The voltage regulator ensures that the alternator does not supply too much voltage, right?
Not much more than that, I think.
I will try to follow a post to troubleshoot:
- let the car sit for half hour after the battery is fully charged, so that all the *** computers do their job
- measure amperage draw as fuses are pulled out one by one
- find which device/circuit drains it.
Looks like idle consumption should not exceed 70-100mA.
I will post results, but feel free to comment.
Thank you
Last edited by somedude; Sep 12, 2016 at 12:59 PM.
MBWorld Fanatic!
Joined: Sep 2011
Posts: 1,657
Likes: 35
From: Austin, TX
2005 C230K(sold), Mk7 Jetta
Yes, what RWD said, at any rpm above ~2000 the charging voltage should be 14.1v. Below 2k rpm, 13.6v is what I see on mine.
If the voltage dropped that low that fast... Something is draining like 300 watts (battery capacity ~ 100Ah * 12v = 1200Wh) Wow
If the voltage dropped that low that fast... Something is draining like 300 watts (battery capacity ~ 100Ah * 12v = 1200Wh) Wow
Super Member
Joined: Sep 2002
Posts: 617
Likes: 1
From: Burnaby
2002 CL203
So you have power seats? if so, it's probably the seat controller. Unplug the power from under the seats and see if that solves it. The seat controller power drain was a fairly common issue.
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GLC300
Thank you, yes I do and I read about that.
I haven't yet started any troubleshooting, I took the day off tomorrow so that I can deal with this.
I also started a new thread on the alternator, as I am trying to understand the entire system. Since my charging voltage is low and there is a possibility that the parasitic drain is caused by the voltage regulator or a shorted diode, I am researching that too.
Thanks again
I haven't yet started any troubleshooting, I took the day off tomorrow so that I can deal with this.
I also started a new thread on the alternator, as I am trying to understand the entire system. Since my charging voltage is low and there is a possibility that the parasitic drain is caused by the voltage regulator or a shorted diode, I am researching that too.
Thanks again
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GLC300
Update: It's not any circuit protected by a fuse, nor the memory driver seat.
With the ammeter connected, I was getting close to 3A draw. I didn't wait for all computers to go idle, but I started to pull fuses.
There is a fuse box on the driver side, under the hood, one at the end of the dasdhboard, same side and a third in the trunk, same side actually.
I pulled fuses one by one and the amperage hovered around 3A, no matter what I did.
I also disconnecter the driver's seat, which is power, same deal.
Tomorrow I will try to disconnect the alternator.
If that's not it, I am at a loss as to what might cause this pasraitic draw.
Please feel free to comment or make suggestions, as I only have one thing left to try.
With the ammeter connected, I was getting close to 3A draw. I didn't wait for all computers to go idle, but I started to pull fuses.
There is a fuse box on the driver side, under the hood, one at the end of the dasdhboard, same side and a third in the trunk, same side actually.
I pulled fuses one by one and the amperage hovered around 3A, no matter what I did.
I also disconnecter the driver's seat, which is power, same deal.
Tomorrow I will try to disconnect the alternator.
If that's not it, I am at a loss as to what might cause this pasraitic draw.
Please feel free to comment or make suggestions, as I only have one thing left to try.
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Thread Starter
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Joined: Aug 2008
Posts: 31
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GLC300
Update
With the battery disconnected overnight I measured 11.6V before reconnecting. That seems a bit low.
Not surprisingly, the engine started. Now it's up on jacks, cooling off.
I will check the alternator for shorts. Hopefully I will have enough access so that I don't have to remove it.
Another update
I disconnected the alternator and right away I get .15A draw for a few seconds, then drops further.
I will now let it sit for half an hour then check the readings again, but I suspect it will drop to 50-70mA as it should, when idle.
Now I know I can replace the voltage regulator without dropping the alternator, but is there any way to test it?
If I replace the VR and it's a diode, I'd be throwing the money away. Sort of the same if I get an alternator and it's just the VR, not to mention the extra wortk to remove it.
I am thinking of reconnecting the leads without the VR and see if there is still a draw. If not, I will assume it's the VR. If there is, must be the alternator.
Reasonable?
Yet another update
The drain only exists with the VR connected and just the power lead connected to the alternator.
Without the VR, with the power lead attached, no drain.
Logic tells me that the diodes, which are connected internally to ground and to the power lead, should not have a short, or the drain would have happened with the power lead connected directly to the rectifier bridge and without the VR.
So I ordered a new one from Autopartsway, as they say it's made by Bosch and matches exactly the one I pulled out from my car.
Please validate (or not) my decision to replace just the voltage regulator.
Thank you very much.
With the battery disconnected overnight I measured 11.6V before reconnecting. That seems a bit low.
Not surprisingly, the engine started. Now it's up on jacks, cooling off.
I will check the alternator for shorts. Hopefully I will have enough access so that I don't have to remove it.
Another update
I disconnected the alternator and right away I get .15A draw for a few seconds, then drops further.
I will now let it sit for half an hour then check the readings again, but I suspect it will drop to 50-70mA as it should, when idle.
Now I know I can replace the voltage regulator without dropping the alternator, but is there any way to test it?
If I replace the VR and it's a diode, I'd be throwing the money away. Sort of the same if I get an alternator and it's just the VR, not to mention the extra wortk to remove it.
I am thinking of reconnecting the leads without the VR and see if there is still a draw. If not, I will assume it's the VR. If there is, must be the alternator.
Reasonable?
Yet another update
The drain only exists with the VR connected and just the power lead connected to the alternator.
Without the VR, with the power lead attached, no drain.
Logic tells me that the diodes, which are connected internally to ground and to the power lead, should not have a short, or the drain would have happened with the power lead connected directly to the rectifier bridge and without the VR.
So I ordered a new one from Autopartsway, as they say it's made by Bosch and matches exactly the one I pulled out from my car.
Please validate (or not) my decision to replace just the voltage regulator.
Thank you very much.
Last edited by somedude; Sep 13, 2016 at 03:35 PM.
Thread Starter
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Joined: Aug 2008
Posts: 31
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GLC300
SOLVED
The new VR fixed the issue. The parasitic drain is gone.
As soon as I connect the battery, I get about 0.8A and then it quickly drops to 0.15A
I didn't wait for the CAN bus traffic to stop, as these numbers look right from get-go.
And I didn't have to remove the alternator for this.
The new VR fixed the issue. The parasitic drain is gone.
As soon as I connect the battery, I get about 0.8A and then it quickly drops to 0.15A
I didn't wait for the CAN bus traffic to stop, as these numbers look right from get-go.
And I didn't have to remove the alternator for this.
