Voltage Regulator

[bpossel]

Hi All!

 :oops: Having a charging issue with the battery.  Battery is new, had alternator bench tested, its good!

Using a battery/volt tester, one that plugs into the cig lighter, shows the following:
1. With lights on & idle speed = ~12.1
2. With lights on & 2500rpm = ~12.9
3. Without lights on & idle speed = ~12.5
4. Without lights on & 2500rpm = ~13.1

My alternator light on the dash is NOT on, no indication of any problem.  All cables are clean and do not appear to be the problem.

 :?: Question: is there a way to test the voltage regulator?  Can this be taken apart, cleaned, fixed, prior to just buying a new one?

Any advice?
Thanks!
Bob

bpossel
Memphis, TN.
1971 280SL
1997 E320

[Naj ✝︎]

Bob,
With good charging, you want over 14 volts.
Your late car should have a 55 amp alternator,but it may also have an internal regulator which is part of the brush plate.

Download Attachment: Volt14.JPG
46.5 KB

Alternator with Internal Regulator on brush plate
Download Attachment: Alt55aIR4.JPG
31.61 KB


Alternator with external Regulator with 3 pin connector Note: Radio Interference Capacitor stuck on the back of this one!!
Download Attachment: Alt35a6.JPG
38.22 KB

naj

[ChrisInNashville]

OK, I have a similar twist.

I rarely drive at night.   Last night, as I hit a bump, head lights, dash lights, and radio faded.   Car idled rough, but I revved it and the lights came back.   Generator light did not come on.

Often, during the day, I idle rough at a light, rev it, and all is well.

Alternator is new, battery is good, all connections that I can see are tight...

Should I just change the volt regulator, or is there something more sinister here?

[hands_aus]

Christie,
What model do you drive? Manual or automatic? I ask because there are lots of differnces between models and that basic info allows people to give more accurate help for your pagodas' problem.

I had a problem with my 250SL cutting out. It turned out to be a loose wire that goes from the ignition switch to the ballast resistor. Tightened the screw on the ballast resistor and no more problems.

There was no spring washer under the screw... there is now.

Worth a look.

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[graphic66]

Check the red indicator light on the dash. It should light up with the key on and the engine not running. I just had this problem with my 406, if the dash light is blown or has a bad connection the alternator will not charge. I don't know if the 113 is like this but it is a pretty easy thing to check and repair.

[mbzse]

quote:Originally posted by bpossel

Having a charging issue with the battery

Electronic regulator
The regulator in the electric system of a vehicle is what makes the voltage be more or less constant - otherwise the voltage would vary, and depend upon engine rpm (alternator rotating at different speeds)
The regulator in early and mid production W113 cars is electromechanical. It is mounted in the engine compartment, for our cars with alternator it is an aluminium box some 70x70x35mm. The connector is downwards.
The device becomes worn with time. It may well corrode inside and stop functioning at some inconvenient time or place...
A wise thing to do is to change this regulator to a modern, fully electronic one. Bosch part number:  019 206 200 70
This electronic replacement fits the same mounting holes as the mechanical type and has the same plug.
The electronic replacement regulator will charge your battery in a more optimal way, and does good things in order to increase battery life span.
The change over to 55A type alternator with integral (electronic) regulator on the 280SL, as descibed by Naj below, came 1st of August 1969.

/Hans in Stockholm

[ChrisInNashville]

It's a '69 280...Generator light works, but it not coming on while driving to indicate a problem.

Just got back from AutoZone where they checked with their computer.   Running 18.3 amps at 2000 rpm.   Diodes were good.   They said it should put out 35 amps...is this correct?

Does this bring me back to the Voltage Regulator? or is there something else?

[hands_aus]

See the pics in the reply by Naj to identify your type of alternator.
The earlier alternators were 35 amp output with NO inbuilt Regulator, while the later alternators had the inbuilt Regulator and were 55 amp output.

Have them check your regulator too.

Did you check the ignition system wiring connections? I could be a loose wire.

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[George Davis]

Christietz,

how did Autozone check you alternator's output?  Did they just check it with only the normal electrical loads in the car drawing power (ignition, blower, lights, etc.), or did they connect a load cell (not sure that's the right term) to test for max output?  If it's the former, then your alternator is probably ok.

From the symptoms you described earlier, there is almost certainly a loose connection or similar problem somewhere.  Assuming battery connections are clean and tight, I'd start at the connections to the starter.  Vibration can loosen things up, and I found one of the smaller wires almost broken down there.



George Davis
'69 280 SL Euro manual

[bpossel]

Hi Chris,

As promised, I took my car to AutoZone and had them test my battery and alternator.  Since my original post, I did install a new 35amp alternator, new regulator and also new battery cables.  Also cleaned all terminal ends on the starter, etc.  Note: Battery was replaced a few months ago….

Anyway…  their tests yielded the following:
Car off, battery showed 12.7 volts
Car running (idle 834 rpm) volts = 13.75
Car running 2000 rpm, volts about the same
Car running (idle 834 rpm) headlights on, volts = 12.9 volts
Amps were showing 1.6 on their machine.  I was told that these were “excess” amps.
All seems to be working very well.

Good luck!
Bob


bpossel
Memphis, TN.
1971 280SL
1997 E320