New Alternator problems
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Joined: Oct 2021
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W204 c350 cdi 2009
New Alternator problems
Hi. I have problmes with my c350 cdi 2009.
Got New alternator and after 2months star getting red battery indicator every couple of days, so i got new alternator again. And start play funny games again after 1month, rmp slightly jumping up and down for little time. voltage at the moment 12.6 after 10-15s jumps to normal over 14v. Battery is good. Alternator with new voltage regulator. Any ideas what's wrong? Thanks in advance.
Got New alternator and after 2months star getting red battery indicator every couple of days, so i got new alternator again. And start play funny games again after 1month, rmp slightly jumping up and down for little time. voltage at the moment 12.6 after 10-15s jumps to normal over 14v. Battery is good. Alternator with new voltage regulator. Any ideas what's wrong? Thanks in advance.
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From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
Voltage swings
Hi. I have problmes with my c350 cdi 2009.
Got New alternator and after 2months star getting red battery indicator every couple of days, so i got new alternator again. And start play funny games again after 1month, rmp slightly jumping up and down for little time. voltage at the moment 12.6 after 10-15s jumps to normal over 14v. Battery is good. Alternator with new voltage regulator. Any ideas what's wrong? Thanks in advance.
Got New alternator and after 2months star getting red battery indicator every couple of days, so i got new alternator again. And start play funny games again after 1month, rmp slightly jumping up and down for little time. voltage at the moment 12.6 after 10-15s jumps to normal over 14v. Battery is good. Alternator with new voltage regulator. Any ideas what's wrong? Thanks in advance.
What you particularly don't want is anything near 12.3v or below while driving.
Let me ask you...:
Why do you keep replacing your alternator ?
How many batteries?
Any current scanned faults ?
Thread Starter
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W204 c350 cdi 2009
I thought i got faulty alternator at the first stage. Warranty gives me new one, and now start do it similar things as the another.
No faults.
Last edited by Uncle_Sigis; Oct 14, 2021 at 04:26 AM.
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W204 C200, BMW E30 M3, 1980Gt Mini, Toyota Corona, KTM 200 EXC.
Are you testing with an external volt meter and engine running?
Usually most cars will be 13.8 - 14.4 volts with engine running.
I think if you are seeing something outside this with engine running I would get it checked out with a scanning device to see if there is any fault codes associated with charging.
Usually most cars will be 13.8 - 14.4 volts with engine running.
I think if you are seeing something outside this with engine running I would get it checked out with a scanning device to see if there is any fault codes associated with charging.
Thread Starter
Newbie
Joined: Oct 2021
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W204 c350 cdi 2009
Are you testing with an external volt meter and engine running?
Usually most cars will be 13.8 - 14.4 volts with engine running.
I think if you are seeing something outside this with engine running I would get it checked out with a scanning device to see if there is any fault codes associated with charging.
Usually most cars will be 13.8 - 14.4 volts with engine running.
I think if you are seeing something outside this with engine running I would get it checked out with a scanning device to see if there is any fault codes associated with charging.
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From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
Sorting VOLTAGE issues...
"Engineering Menu" is exactly what you want to be displaying to witness battery VOLTs and AMPs while driving.
Positive AMPs mean battery is charging.
Negative AMPs mean battery is discharging ie. paying for the show!
12.6V is called FLOAT voltage, it's enabled so ALT keeps supplying 100% of car power but without overcharging lead-acid battery when it's already fully charged.
Voltages from 13x to 14.xV are used to charge battery under BULK and ABSORPTION rates.
More is NOT better!
Alternator voltage is dynamic, not static... it keeps adapting to match your car's demands, much like a CTEK battery charger simply does.
If at anytime during driving the voltage swings below 12.6V like 12.3... 11.x or lower: that's trouble around the corner.
Pay close attention to voltage once the battery is charged up and ALT exits 13xv/14xV.
Positive AMPs mean battery is charging.
Negative AMPs mean battery is discharging ie. paying for the show!
12.6V is called FLOAT voltage, it's enabled so ALT keeps supplying 100% of car power but without overcharging lead-acid battery when it's already fully charged.
Voltages from 13x to 14.xV are used to charge battery under BULK and ABSORPTION rates.
More is NOT better!
Alternator voltage is dynamic, not static... it keeps adapting to match your car's demands, much like a CTEK battery charger simply does.
If at anytime during driving the voltage swings below 12.6V like 12.3... 11.x or lower: that's trouble around the corner.
Pay close attention to voltage once the battery is charged up and ALT exits 13xv/14xV.
Thread Starter
Newbie
Joined: Oct 2021
Posts: 6
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W204 c350 cdi 2009
"Engineering Menu" is exactly what you want to be displaying to witness battery VOLTs and AMPs while driving.
Positive AMPs mean battery is charging.
Negative AMPs mean battery is discharging ie. paying for the show!
12.6V is called FLOAT voltage, it's enabled so ALT keeps supplying 100% of car power but without overcharging lead-acid battery when it's already fully charged.
Voltages from 13x to 14.xV are used to charge battery under BULK and ABSORPTION rates.
More is NOT better!
Alternator voltage is dynamic, not static... it keeps adapting to match your car's demands, much like a CTEK battery charger simply does.
If at anytime during driving the voltage swings below 12.6V like 12.3... 11.x or lower: that's trouble around the corner.
Pay close attention to voltage once the battery is charged up and ALT exits 13xv/14xV.
Positive AMPs mean battery is charging.
Negative AMPs mean battery is discharging ie. paying for the show!
12.6V is called FLOAT voltage, it's enabled so ALT keeps supplying 100% of car power but without overcharging lead-acid battery when it's already fully charged.
Voltages from 13x to 14.xV are used to charge battery under BULK and ABSORPTION rates.
More is NOT better!
Alternator voltage is dynamic, not static... it keeps adapting to match your car's demands, much like a CTEK battery charger simply does.
If at anytime during driving the voltage swings below 12.6V like 12.3... 11.x or lower: that's trouble around the corner.
Pay close attention to voltage once the battery is charged up and ALT exits 13xv/14xV.
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Out Of Control!!
Joined: Apr 2019
Posts: 12,160
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From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
Low voltage with ENGINE on...
11.6V with engine running confirms a voltage issue. How many Amps??
Any picture of instrument cluster??
TESTING:
Does turning Headlights:ON gets you a voltage near 13.5v or no difference at all?
Are you getting a good stable voltage (13...14V) with the alternator control plug disconnected?
Last edited by CaliBenzDriver; Oct 15, 2021 at 12:17 PM.
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Thread Starter
Newbie
Joined: Oct 2021
Posts: 6
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W204 c350 cdi 2009
When i turn headlight on makes no difference.
Out Of Control!!
Joined: Apr 2019
Posts: 12,160
Likes: 6,881
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
Your battery has been charged full recently, right?
Disconnecting alternator plug should command the ALT REG to output internally controlled voltage. (Regulator is quite smart on its own with an internal Amp measure).
While under your car... check the fat GROUND STRAP TO CHASSIS has clean electrical connections (not rusted/oxidized)
👍
Thread Starter
Newbie
Joined: Oct 2021
Posts: 6
Likes: 1
W204 c350 cdi 2009
... that does seem like a low voltage regulation.
Your battery has been charged full recently, right?
Disconnecting alternator plug should command the ALT REG to output internally controlled voltage. (Regulator is quite smart on its own with an internal Amp measure).
While under your car... check the fat GROUND STRAP TO CHASSIS has clean electrical connections (not rusted/oxidized)
👍
Your battery has been charged full recently, right?
Disconnecting alternator plug should command the ALT REG to output internally controlled voltage. (Regulator is quite smart on its own with an internal Amp measure).
While under your car... check the fat GROUND STRAP TO CHASSIS has clean electrical connections (not rusted/oxidized)
👍
