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Hello Gents,

I'm a brand new owner of an '86 190E. I have had a few issues with the battery getting enough juicy back to be able to run the car.
in the beginning, it worked well. then slowly I would drive it for a little and it would die on me. I changed the alternator and it continues to happen.
the problem continued for a little. 4 alternators later the problem was still there then I realized that the belt tensioner was broken and that could be the problem.
A dear friend of mine helped me change it and it worked fine. the car was parked for over a month. I used it twice and now the problem came back. the battery is not getting enough volts while the car is in use. Any help would be amazing. thanks in advance!
 

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Welcome to the forum. Would be nice to know your location on planet earth so please update your profile.
Please report on the voltages. Can be measured from the cigarette lighter point for convenience.

What is the voltage when you start it in the morning?
What does it settle to after running nothing electrically with the car running in town for 30 minutes
What is it after this point and the headlights (high beams) and the fan switch maxed to speed 4.

- Cheers!
 

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Welcome to the forum. Would be nice to know your location on planet earth so please update your profile.
Please report on the voltages. Can be measured from the cigarette lighter point for convenience.

What is the voltage when you start it in the morning?
What does it settle to after running nothing electrically with the car running in town for 30 minutes
What is it after this point and the headlights (high beams) and the fan switch maxed to speed 4.

- Cheers!
@ Dolucasi, thanks for reaching out. FYI I live in Richmond Virginia and will update my profile soon.
I'm very new at fixing my own cars and do not have all the tools or part of the tool but I hope that with time I can acquire some. After reading a few posted replays on other forums, I will be trying the following tomorrow.
taking the old/new alternator back and getting a Bosch and getting a new serpentine belt on. it seems like that along fixed a lot of the problems for some folks before.

After that, I will report on my findings.
 

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My advice would be to instead of replacing parts indiscriminately, diagnose the problem first. That way you will learn your car and save a lot of money in the process.

The most important tool you need to diagnose and repair these cars (other than wrenches and such) is a voltmeter/ohmmeter. A cheap one would be under $40.

The alternator for example. They never go bad on these cars in dry climates. Mine is the original at over 30 years and ~200K miles. It may have been replaced once at 150K miles but I have to check the records. The voltage regulators are wear items but they also last a long time and are a fraction of the cost of an alternator, I think mine was replaced only once. So it seems you may have replaced your alternator multiple times for no good reason.

Same goes with the serpentine belt. Generally if that is in dire condition, there are other parts that may need replaced too (like dampener, tensioner, etc). If you do not hear it slipping, maybe put that off till later.

So a voltmeter and a USB charger with a voltmeter display on it ($12 online) that plugs into the cigarette lighter is worth $1000 of unnecessary repairs. You can also monitor your system voltage constantly, and not use the lighter for more harmful matter.

- Cheers!
 

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Otto_leon17, I had a similar issue with my 190E. Turned out it was the voltage regulator. It was a simple fix as it can be replaced without removing the alternator. I bought a cigar lighter plug in voltage meter on Dolucasi's recommendation and I am now able to constantly monitor the alternator output as I drive.
 

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Can you see the charge light bulb on the dash ,and is it on when you switch the key on to start,, and extinguished after the engine starts up?.. This bulb if its not working can stop the battery charging up .
 

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Discussion Starter #7
Otto_leon17, I had a similar issue with my 190E. Turned out it was the voltage regulator. It was a simple fix as it can be replaced without removing the alternator. I bought a cigar lighter plug in voltage meter on Dolucasi's recommendation and I am now able to constantly monitor the alternator output as I drive.
thank you for your response.
 

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@ Dolucasi, thanks for reaching out. FYI I live in Richmond Virginia and will update my profile soon.
I'm very new at fixing my own cars and do not have all the tools or part of the tool but I hope that with time I can acquire some. After reading a few posted replays on other forums, I will be trying the following tomorrow.
taking the old/new alternator back and getting a Bosch and getting a new serpentine belt on. it seems like that along fixed a lot of the problems for some folks before.

After that, I will report on my findings.
Can you see the charge light bulb on the dash ,and is it on when you switch the key on to start,, and extinguished after the engine starts up?.. This bulb if its not working can stop the battery charging up .

I can see it and it is on and then it does turn off once engine is on
 

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@ Dolucasi, thanks for reaching out. FYI I live in Richmond Virginia and will update my profile soon.
I'm very new at fixing my own cars and do not have all the tools or part of the tool but I hope that with time I can acquire some. After reading a few posted replays on other forums, I will be trying the following tomorrow.
taking the old/new alternator back and getting a Bosch and getting a new serpentine belt on. it seems like that along fixed a lot of the problems for some folks before.

After that, I will report on my findings.

@dolucasi here are my findings ;

when the is on and running it puts out the following voltage
13.7
with headlights on 13.7
with headlights and fog lights 13.6
with ac in 13.5
with radio 13.5
with everything on and AC on max, it puts out 12.5

when it's not moving
13.5 start
headlights 12.5
with fog lights 12.1
both lights on 11.7
with radio 12.2
ac max 11.7
headlights and ac on max 11.3
everything on 11.4

this is after I replace the serpentine belt for a new one and a new alternator from advance. as well.
 

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Your voltages when idling are much lower than mine. I believe I have never seen below 12.8V with most equipment on. It almost looks like you are running out of juice, or maybe it is a regulator issue.

Certainly 11.4V sounds like an issue to me.

I would be concerend if the voltage was below 12.5V at any point in time.
 

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I also wonder is there is a ground loop issue. How does your ground strap look to the chassis under the car?
You might want to take it off and clean it off.
 
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