do I need a new voltage regulator?

[merrill]

so, before I started tearing down my motor to send out for rebuild,
I checked the following

before starting
battery voltage 12.59 volts - brand new batt
voltage at ballast resister in - 11.2
voltage at ballast resister out - 6.66


at 1000 rpm the voltage from the generator went up to 13.8 volts but never to 14 or higher.
the car had to be at 1000 rpms or higher or the volage would drop and the car would want to stall.

thanks
matt

Matt
66 230 sl - "white"
78 300 D - Blue
98 C230

[Naj ✝︎]

I did  :?

With readings similar to yours, with good results!!
Alternator fairly new and therefore not suspect.
naj

68 280SL

[J. Huber]

This has me thinking about my situation. I believe I have the original voltage regulator. Sometimes on cold start-up my red light lingers until I give some throttle. Battery is solid. Is the said regulator a plug and play kinda thing? because I'd be willing to spring for a new one -- if I thought it might help something -- and that I could hook it up myself...give me something to do on a cold winter day.

James
63 230SL

[Naj ✝︎]

Hello, James,

I would invest in a volt meter ( / multimeter) and check the voltage (even across the battery) with engine running.
14V to 14.4V would be nice [:p]


Download Attachment: Volt14.JPG
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naj

[Ricardo]

James
Yes it is "plug and play"...it's the silver colored rectangular cannister on the passenger inner fender. It is possible to open these up and clean up the points of the relay inside and this may help with your red light situation. If the points have become encrusted with deposits, they may need the extra current to pull the points closed, that revving the engine would provide.
Now I can hardly imagine a cold winter day in California. I certainly couldn't play with anything electrical on a cold winter's day here, near Ottawa, at least not without breaking the wires  :evil:

[J. Huber]

Thanks Guys. I think I may have a volt/multimeter back from when I was checking my TTS and CSV? I will check my connections first then test the voltage. Now, Naj, what exactly am I hooking to what to check things?

Ricardo, Re: cold California days...The stereotype for CA weather is mostly true -- especially Southern CA (LA, San Diego, SB, etc). I lived in Santa Barbara for 30 years. It was Pagoda driving all year round. For the last 8, however, I have somehow found myself living in the woodsy Sierra Foothills. 4 distinct seasons. However, the winter is much, much milder than your Canadian winters. Snow and rain might keep me grounded for a day or two but things dry out pretty quick...

James
63 230SL

[glennard]

Didn't the ballast resistor get bypassed in the 'Start' position and back in  in 'Run' on the later SEs?

[hands_aus]

Matt,
1.37 volts drop between the battery and the input side of the ballast resistor seems a lot to me.
That voltage usually comes directly from the battery via the ignition switch.

Recently I had something similar but it turned out to be a faulty diode in the alternator creating the low voltage situation.
Eventually I had the alternator rebuilt without any need to adjust the regulator.

Have you thought of having both the alternator and regulator tested? Maybe a conversation with your local auto electrician will save all the bother.

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

[Naj ✝︎]

Hello, James,
 

quote:Now, Naj, what exactly am I hooking to what to check things?

Connect negative probe of voltmeter (black wire ?) to Battery (-).
With engine running, (+) probe to Battery (+) should read around 14V to 14.4V.
Positive probe to Ign switch side of ballast resistor ~ 14V
Positive probe to Coil side of ballast resistor  ~ 13V
These were my readings on my 230SL.

glennard
 

quote:Didn't the ballast resistor get bypassed in the 'Start' position and back in in 'Run' on the later SEs?

Yes. That and the higher HP starter fitted to a 113 does wonders for cold starting. One of the top enhancements for a Pagoda 'in my book'.

naj

68 280SL

[J. Huber]

Well Naj -- if I did it correctly I may have troubles.

Battery -- 12V
Ign Side -- 11.5V
Coil side -- 9.5V

What would you make of these?

James
63 230SL

[Naj ✝︎]

James,

Readings with engine running?

naj

68 280SL

[J. Huber]

Yes. Not warmed-up but running. Also, I just removed the VR and cleaned the "spade" connectors. Retried. Same numbers. Did I read that the VR can be opened and relays cleaned? How might this be done? Or does it sound even more serious than all that...?

James
63 230SL

[ctaylor738]

I faced the same problem a couple of months ago and did some research.  Here is a link to what I found and an explanation of how to test the VR:

http://index.php?topic=5964

Bosch sells a replacement solid state VR that plugs into the original harness - they even put a cover on it to make it look original.



Chuck Taylor
1970 280SL #14076
Falls Church VA

[J. Huber]

Thanks Chuck. I think testing the VR might be a good idea. It may be that I won the trifecta: need to buy a new battery, a new VR, and a new alternator?

Anyway, I tried something else. Yesterday's readings were with an ice cold engine. Since the sun came out today, I went for a nice spirited (albeit chilly) drive this morning. Then checked numbers again. Everything went up about a 1/2 volt:
battery 12.5  
Coil side 9.85
Ign side 11.95

What would the negative symptoms be to these low numbers? Car seems to run good. Lighting seems normal.



James
63 230SL

[Naj ✝︎]

Hi, James,

The way your car starts and runs, I am suspicious of the voltmeter??

Some have a way of calibrating them when they have been lying around with the battery connected...
 :?:
naj

68 280SL

[George Davis]

James,

temperature affects battery voltage, I'd guess the 1/2 volt increase was related to the battery being warmer on the second test.  I wouldn't be too bothered by your readings.  For a bit more fun, test the battery voltage with the ignition off, then start the engine and test again at idle, then once more at 1500-2000 rpm.  Not that I have any idea why, it just sounds like fun...

George Davis
'69 280 SL Euro manual

[J. Huber]

Thanks as always Naj and George (ps good to hear from ya). I wondered about the voltmeter myself -- although its not too old and kind of new-fangled. I did notice there was a third port for the test wires to plug into. I tried that one and got a nice scary spark from the + side of the battery! Went back to old ones. Maybe I'll spin down to a service station today and have the guy test things with his meter. I bet they would do that...

James
63 230SL

[J. Huber]

Here's my update: went to a mechanic (VW guy not MBZ -- but nice nonetheless) who tested things with his handheld. Showed same numbers as mine. However, and this fulfills George's idea of fun -- we tested it with some throttle (around 2000RPM). Battery cranked right up to 14.2 or so. Ignition side 14. Coil side 13. He said that all seems normal. His idea (after I planted the seed was maybe the Voltage Regulator was wearing out...) Said it might be hard to find parts for an older car like this. (I smiled).

James
63 230SL

[merrill]

James,
I just ordered one from cheryl at K&K.  I think the replacement is for my 230 sl is $45

matt

Matt
66 230 sl - "white"
78 300 D - Blue
98 C230

[J. Huber]

Thats great Matt. Continue to keep us posted on your progress! I will be calling Cheryl tomorrow -- that is a better price than I saw from my two usual suppliers...

I would think mine and yours take the same VR ('63 vs '66). I am glad I finally figured out what to buy my car for Christmas!

James
63 230SL

[J. Huber]

Update on my Voltage Regulation. I just installed a new one from K&K hoping to bring my idle numbers up from:
12.5 battery
11.5 ignition side and
9.5 coil side.

Didn't change. So that leaves either battery or alternator, no? The fact that the numbers climb to normal when I increase RPM to 2000 or so, makes me think its the battery. What do ya'll think?

James
63 230SL

[Cees Klumper]

Hi James - you could try the battery from your 'regular / day' car to see if this is the cause?

Cees ("Case") Klumper in Amsterdam
'69 white 280 SL automatic

[J. Huber]

That's a good idea Cees. Now the fact that my "other" cars are a F150 Truck and Chevy Tahoe wouldn't matter would it? I am sure battery posts are different -- will they still work?

James
63 230SL

[66andBlue]

quote:Originally posted by J. Huber
.. I am sure battery posts are different -- will they still work?

James,
use a jumper cable and connect the F150 (or Chevy) battery to the cables on the Pagoda. Just remember what + and - means!  

Alfred
1966 blue 230SL automatic

[George Davis]

Hi James,

much as I enjoy spending your money, I actually don't think you need a new battery or alternator at all.  But if the voltage numbers bother you, I vote for the alternator.



George Davis
'69 280 SL Euro manual