Alternator Test Quick Question - Page 3 - PeachParts Mercedes-Benz Forum

JamesDean · #1 01-08-2010, 12:39 AM

uhm...

well I kinda locked myself out of my house. Its cold outside. I went out to get a drink and check the battery charger on my SD in the garage. Then I went back in to get the light to do the work...and the door was locked..as well as every window and other door around my house.

Furthermore, the doorbell is useless, as is holding down the van's horn. I had an ingenious plan though: I was able to start up the one SD that I am working on...I was going to drive to my grandma's (about 1 mile away) and phone home..(my cell was in the basement) and tell my parents to unlock the door. However this plan was a failure as I couldn't figure out how to bypass the steering lock out. I was proud that I got the engine to run though.

What fun. Also, there is about a pound of oranges and grapefruit on my roof.

Needless to say I'll resume work on the SD tomorrow. I have a few other things to reconnect up (switch off vac line namely)

I ended up banging on the ceiling (my parents room is above the garage) with a 4 foot lead pipe. Impressively enough, I manage to break a wire for the garage door opener clean in half with the blunt end of the pipe (i had a coupler on it)....

layback40 · #2 01-08-2010, 12:48 AM

Barry,
The voltage regulator monitors the output voltage of the alt and attempts to keep it at a preset voltage. It does this by adjusting the voltage across the rotor coils. The difference with high amp regs is they are just able to give a higher voltage across the rotor coil. The low amp ones just reach a certain voltage and then flat line. The higher the primary voltage ( rotor coil) the higher the output of the alt.

layback40 · #3 01-08-2010, 12:52 AM

James,
It wont hurt to put the battery on the charger over night. That wont fix your alt though.

JamesDean · #4 01-08-2010, 01:06 AM

Quote:

Originally Posted by layback40

James,
It wont hurt to put the battery on the charger over night. That wont fix your alt though.

Agreed. I dont believe it will fix it either. Atleast I'll be able to check if the batter holds charge and once its fully charged I'll retest to see Barry's comments apply. It never hurts to test and I've got time.

I'm debating on bringing the battery in to charge it. I dont really feel like leaving the hood open, especially if it snows. That way I can check it periodically.

Whats the worst that could happen? I get locked out...oh wait that did happen. haha. brb.

barry123400 · #5 01-08-2010, 01:16 AM

Just for fun reach down to the alternator pulley tomorrow morning. Grab on to the cooling fins just behind the pulley itself. Can you turn the pulley by hand? I assume you may have already checked this.

On occasion if loose the belt will not squeel. But alternator output will be substandard. You should never be able to turn that pully by hand. Remember
the transfer of several horsepower to the alternator are required at full alternator output.

Also try not to lock yourself out again this evening. If my wife and myself were your parents we might be then discussing how safe it was to let you out. Or I would be asking the wife if you were really one of mine.

All kidding aside it is nice to see you helping out your dad. I think you will get to the bottom of this pretty fast.

JamesDean · #6 01-08-2010, 01:36 AM

Quote:

Originally Posted by barry123400

Just for fun reach down to the alternator pulley tomorrow morning. Grab on to the cooling fins just behind the pully itself. Can you turn the pully by hand? I assume you may have already checked this.

On occasion if loose the belt will not squeel. But alternator output will be substandard. You should never be able to turn that pully by hand.

Also try not to lock yourself out again this evening. If my wife and myself were your parents we might be then discussing how safe it was to let you out. Or I would be asking the wife if you were really one of mine.

All kidding aside it is nice to see you helping out your dad. I think you will get to the bottom of this pretty fast.

I checked the belts yesterday they seemed ok but I will look more into them and check again.

When I went to get the battery out, I grabbed a set of keys and my phone and made sure both the garage and side door were unlocked.

Always fun stuff.

Plans for tomorrow:
1) batt should be charged fully (according to research: roughly 12.66 volts see post #13)
2) reinstall voltage regulator
3) conduct full battery of tests as laid out in previous posts.
4) charging system test from the parts store

As always, I appreciate everyone's quick responses and helpful tips.

-Kris

barry123400 · #7 01-08-2010, 01:50 AM

Well your still awake and in the house.

I never trusted the deflection test. I found that a notorious subjective test that does not allow for glazing and wear etc over time. In otherwords it can fool anyone. A vee belt riding on it's bottom could be extremely tight by deflection and the pulley will still turn by hand for instance.

So I switched over to the pulley test. I do not think that can decieve anybody. Plus I was never able to describe the deflection methology properly to another person. The distance or span alone between pulleys has to be taken into the calculation. For example a half inch deflection with no applied
force vector standard is pointless. No two belt tensions would be identical.

The only time I use the deflection test is to try to acertain if the belt or belts are too tight and perhaps stressing the bearings.

I have also locked myself out on occassion. The wife preffered hatchback cars for awhile there. She was leaving the keys inside when locking the car. By leaving the hatchback unlocked she did not have to phone me to bring other keys.

You also might remember that famous one. The guys girlfriend was scratching at the locked bedroom door. He felt so bad he got up and let her out.

Well time for bed I suppose.

layback40 · #8 01-08-2010, 01:42 AM

Good luck James! Let us know what you find.

#9 01-08-2010, 11:17 AM

It sounds to me like your charging system is working. If the battery doesn't hold a charge, I would suspect the battery is the problem.

JamesDean · #10 01-08-2010, 11:31 AM

just got back from Advance Auto...

slightly less detail than I had wished for but they said that the alternator was outputting fine and that the battery was low

Results:
http://imgur.com/ALD1P.jpg
sorry for the crap angle on the scan

layback40 · #11 01-08-2010, 07:10 PM

alt cant be putting out full amps as it is not keeping up with lights /blower /defrost.
if it was me, I would try another regulator.

JamesDean · #12 01-08-2010, 08:33 PM

I agree with you...

I left the car sit outside w/ heater plugged in and I checked the batter voltage and it has dropped to 12.42v.

I will swap the regulators real quick and run my usual battery of tests.

Another thing the guy at Advance mention was that when I started the car the alternator wasn't putting anything out. Once the engine was revved a little bit the alternator started outputting normal voltage levels.

Is that normal operation? I've seen this in the past on my other SD as well. I've not been able to explain/repair. The other SD (the Gold SD) has a new alternator too.

JamesDean · #13 01-08-2010, 09:09 PM

Observation:
Different part number on the Gold SD's regulator: 1 197 311 022
Green SD's regulator: 1 197 311 023

Not sure what is different.

Test results were much more encouraging:

Battery - Car Off - 12.42v
No GP Light On
Key On - Car Off - 11.42
Glow Plugs verified to be running, voltage @ GP #1 - 11.07v
Started Idling - 13.9v -
Started Revving - 14.02v peak
Only Blower High @ Idle - 12.90v
Only Blower High @ Rev - 13.80v
Blower High + Lights @ Idle - 12.12v
Blower High + Lights @ Rev - 13.60v
Blower High + Lights + Rear Defrost @ Idle - 11.74v
Blower High + Lights + Rear Defrost @ Rev - 13.00v
Blower High + Brights + Rear Defrost @ Idle - 11.66v
Blower High + Brights + Rear Defrost @ Rev - 13.04v (this number climbed gradually the longer I held the engine at higher rpm)

It looks like a new voltage regulator is in order. This seemed to have been the problem.

If you guys agree, I'll most likely keep this 022 regulator in the Green SD and buy a new one for the Gold SD.

If at all possible one that will put out more. If not I'll find a 022 regulator.

Let me know what you think.

A brief search on some parts websites turned up 1197311028 when I entered either part number the 022 and the 023

layback40 · #14 01-08-2010, 09:21 PM

one of those regs may be a 55amp , the other a 65amp. I would ask the place you are getting your reg from what are the details on each part number.
Given that you are not in a hurry, you could always pose the question to Phil on here at Fastlane. I cant buy from Fastlane as the wont ship outside of the USA.

It looks like the other reg has done the job. The climbing amps while revving indicates the battery is charging. only having to replace the reg is cheaper than an alt.
Good luck!!

JamesDean · #15 01-08-2010, 09:50 PM

I sent phil off an email.

I always believed that alternator power output was largely a function of stator/rotor coil.

My search across many websites leds me to the "updated" regulator: 1 197 311 028. Looks like between $20-$35 or so. Not bad at all.

One issue still remains: the fact that the GP light on the dash doesn't come on 100% of the time. Every time I've tested the GP system its passed without issue. Every time the key is turned, the box clicks and voltage appears at the plugs. I know its not the relay box because I've swapped the two SD's relay boxes.

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