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93 190E 2.6; 82 300 SD Turbo
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Discussion Starter #1
hey does anyone have a voltometer, (i dont know if thats what its called or not) the gauge that reads the volts the alternator is putting out in their 126?

how do i install one ? I mean i want to install on so it looks stock. so my best place would be where that economy gauge is (i dont have one i just have a space) i mean is there a instrument cluster that has that built in it? In all the 126s i've seen i've never seen one.


-Kris
 

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1991 500SEC sub 50K mi. 1987 560SEC Now 150K mi. 2018
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4,210 Posts
Hi Kris,

Both you and jdc1244a are correct. As jdc suggests, the charge light should give the driver sufficient information on charging.
That said, if one were to modify the instrument cluster to include a real gauge in addition to the lamp, then a voltmeter would be an appropriate choice, probably a VDO brand would 'look' right.

I say voltmeter as I've had direct experience installing an aftermarket ammeter into the dash panel on one of my cars some years ago. After the initial start, the amp gauge would read however many amps were going into the battery, then within a few minutes would read just an amp or two on the plus side for the rest of the trip - almost zero charge no matter what lamps and accessories were being used. There was nothing wrong with the alternator or wiring, just the solid-state regulator would adjust to differing electrical needs almost invisibly. At least with a voltmeter, one could see the battery voltage staying up around 13.6v - 14.2v and know the charging is OK when you flip the switch for those big Hella rallye lamps - turning night into day... [;)]

Personally speaking, I wouldn't modify my instrument cluster with extra components and wiring. That's just me, your mileage may vary...[:)]

Good luck & Cheers, MBL
 

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87 420SEL, 89 560SL, 92 300TE
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62 Posts
When I got my Escort Passport SR7 concealed radar/laser detector, I found out that one of the "screensaver" modes on the unit - which is displayed between radar alerts - is a voltage display. The SR7 also has alarms for "high voltage" and "low voltage", with selecteable thresholds. Its a pretty handy gizmo, but kinda pricey - over $1000 retail with (mandatory) professional installation - but they're coming down. The Beltronics RX75 is basically the same unit and is a few dollars cheaper. I found my SR7 on eBay for around $400.

As a radar and laser detector, it is at or near "best of class", with best-case detection ranges measured in miles (X-band, 4.2 miles, K and Ka band, 4 miles). It features front and rear laser sensors and a front-mounted radar receiver. There is also a single-LED "remote display" - it shows green until an alert, then flashes red with the flash-rate proportional to the signal strength. This can be mounted into the cluster for a completely concealed look. There is also a remote mute/volume button, so the control panel/display unit can be "tucked away" out of sight- though this wouldn't provide your voltmeter.

If you have need for a radar or laser detector, check it out- then you will get a digital voltmeter also. It doesn't look quite "stock" - check my photos at http://www.benzworld.org/forums/forums/thread-view.asp?tid=1200563&posts=8&hl= - the sixth photo down shows the SR7 under the stereo. More info on the SR7 is at http://www.radarbusters.com/products/escort/sr7.asp .

Sorry if I'm babbling off-topic - but this is the coolest "voltmeter" I've ever had in any of my cars!

-Robert
 

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93 190E 2.6; 82 300 SD Turbo
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1,678 Posts
Discussion Starter #5
thanks all, i wont be doing any modifications now that i know that about that battery light. the work and effort wouldnt be worth it. However i do have 1 question
what is the normal idle on a 300SD? I found a sticker (i tihnk) saying it is 750 +/- 100 RPM MFR Adjusted. According to my tach i run at 500, when i revv the engine my headlamps get brighter as so my interiors.
 

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1991 500SEC sub 50K mi. 1987 560SEC Now 150K mi. 2018
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4,210 Posts
Hey there J.D.,

Out all day (in the Volvo[:(] with good tunes[:)]) and saw you post updates..

I was incorrect in my earlier (without breakfast) post, the general healthy voltage output should range between 13.8 - 14.2 volts.

From experience, I replace the alternator 'Brush Pack' or 'Voltage Regulator' at approx. 80,000 miles on every 'modern' car I own. 2 screws, inexpensive, and oh, surprise! (the charge lamp won't come on if the brushes are worn.... and the charge is failing while driving)... Yes, I did say that. I've seen it over & over with quality cars racking up the miles. A V/Reg. picture below.

The idle speed chart for your 300SD is there too.

Cheers, MBL
 

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93 190E 2.6; 82 300 SD Turbo
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1,678 Posts
Discussion Starter #7
thanks for the chart, yeah my idle is low, 500rpm [V]
does it say in that book u have how to raise it? I am hoping to get my service cds sometime here soon i duno when thou.

Also, I just had my Volt regulator replaced about 3 months ago because i was having trouble maitining the charge on my battery. Took it to my "normal" car mechanic he used this interstate battery tester and said the battery was fine that it could be the alternator or the volt regulator, so same day i goto my "benz" mechanic and he replaces the volt reg. everything seems fine a week later guess where I am at, benz mechanic's garage, he lugs out this monstrous battery tester and ah bad battery! tosses in a new one and im all set.
 
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