Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help




Go Back   PeachParts Mercedes ShopForum > Technical Information and Support > Tech Help

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 11-27-2002, 02:38 PM
Registered User
 
Join Date: Oct 2000
Location: Lansing, Michigan, USA
Posts: 49
Delay in alternator kicking in? Battery dies.

I have searched the archives, couldn't find anything.

I have a 78 240D. My battery drains every 3-4 days. There is a 3.5 milliAmp draw when the car is shut off. I assume that is the clock. When I first turn on the car, and let it idle, the voltage remains about 12.4 for 4-5 minutes. Then it climbs to 13.9-14.4 pretty quickly. Is this normal? I only have a 5 minute drive to work and maybe it is using the batttery and not charging fast enough.

Does this sound right? The alternator is a DURALAST (<1 month old). I know I should have gone with OEM, but I was suffering from a spending disability that day.

Could it be the wires inbetween the alternator and the battery? Is there a wiring set that I can just replace?

Thanks,


BTW, I replaced my old loop plugs with the fast glow from fast lane. The difference is AWESOME! Hotter glows, less smoke, and I started it at 15 degrees without plugging it in. Undreamt prior to the switch.
__________________
81 300D 250K (sold)
79 240D 200k
83 Volvo Station Wagon (282k)
Reply With Quote
  #2  
Old 11-27-2002, 02:54 PM
1992300e
Guest
 
Posts: n/a
a thought

I am farily confident that a 5 minute drive to work would not lead to dead batteries as there are many people who drive a short distance to work and don't experience this problem.

I would think this may have something to do with the new alternator / voltage regulator. Have you had it tested? From your note it looks as though the alternator is putting out what it should.

How dead was the battery in the first place? If a battery gets really dead it will not take a meaningfull charge again, someone has told me something about reversing polarity?

Did you install a new battery with the new alternator??

Hope this helps,
Joel
Reply With Quote
  #3  
Old 11-27-2002, 03:05 PM
Registered User
 
Join Date: Oct 2000
Location: Lansing, Michigan, USA
Posts: 49
I did have it tested at Autozone - the battery was good - and so was the alternator - except that it does have this delay in charging.

The battery is exactly 23 months old. I wish it were only the Battery, I have a 2 year free replacement warranty on it.
__________________
81 300D 250K (sold)
79 240D 200k
83 Volvo Station Wagon (282k)
Reply With Quote
  #4  
Old 11-27-2002, 03:16 PM
1992300e
Guest
 
Posts: n/a
Not sure

Not sure what a typical drain would be when not running, is it possible your reading is excesive?

Again, I would not think the five munites to work would be the cause.

Joel

Sorry, I suck at electrics.
Reply With Quote
  #5  
Old 11-27-2002, 03:35 PM
dpetryk's Avatar
Electrons can do anything
 
Join Date: Sep 2001
Location: Houston, Texas
Posts: 1,071
Well IMHO, if it takes five minutes for the alternator to start charging and you only drive it for five minutes to work then it seems to me that you are not charging the battery during the drive and YES that will deplete the battery.

Something is wrong with the alternator. It should start producing charging current within seconds after the engine starts.
__________________
I got too many cars!! Insurance eats me alive. Dave

78 Corvette Stingray - 3k
82 242 Turbo Volvo - Manual - 270k
86 300e 5 speed manual - 210k
87 420sel - 240k
89 560sl - 78k
91 420sel - 205k
91 560sel - 85k
94 GMC Suburban - 90k
97 Harley Davidson Heritage Softail - 25k
00 GMC Silverado 1 ton 30k
Reply With Quote
  #6  
Old 11-27-2002, 03:41 PM
Registered User
 
Join Date: Oct 2000
Location: Lansing, Michigan, USA
Posts: 49
DPETRYK

That is what it seems like to me. The second logical problem is that if the voltage from the alternator is getting to the battery in five minutes, then the wires between the alternator and battery are good, no? But it is a brand new alternator and I had it tested before I left the store - no problems.

Does anyone know how a voltage reg works and if such a delay is common??
__________________
81 300D 250K (sold)
79 240D 200k
83 Volvo Station Wagon (282k)
Reply With Quote
  #7  
Old 11-27-2002, 05:39 PM
Registered User
 
Join Date: Feb 2002
Location: Virginia
Posts: 550
I'm taking a stab in the dark here, but could the issue be that your alternator isn't putting out enough voltage to charge your battery? I've heard that some of the newer maintenance free batteries in particular need a higher voltage than the older alternators produce. I know this would not produce the delay in charging phenomenon you describe, but I wonder if maybe the folk at Autozone just misdiagnosed that??? Maybe?? Just a thought. . .
__________________
Tjohn

82 300 SD
77 450 SL (gone)
Reply With Quote
  #8  
Old 11-27-2002, 06:01 PM
jbaj007's Avatar
Registered User
 
Join Date: Jun 2001
Location: Santa Monica, CA
Posts: 2,053
Josh,
I had the same (similar) problem. Short trips, delayed alternator output (although I never saw 14.4 volts), dead battery every week. Assuming you checked everything with a 100% battery charge (75% is minimum for tests according to Bosch), you have a bad alternator. I replaced mine and no more midnight Sunday driveway charging for me. 4 to 5 minutes is way to long; around 10-20 seconds on a good charging system to reach 13.8 volts at ~1000 rpm.(at most)
__________________
The Golden Rule

1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later)
Reply With Quote
  #9  
Old 11-27-2002, 06:03 PM
Registered User
 
Join Date: Jun 2000
Location: Saugus, CA USA
Posts: 1,989
I had a car do exactly that

Except I had a 45 minute drive to work so it was a non problem. Whats happening is your alternator isn't "starting." Alternators are esentially self starting, and yours isn't. Part of that effect is the dash "alternator" light, check that, it should come on with the ignition on and the engine off.


A trick I did was after everything warmed up a little reving the engine up. That helped it "start" sooner.
Reply With Quote
  #10  
Old 11-27-2002, 07:32 PM
dpetryk's Avatar
Electrons can do anything
 
Join Date: Sep 2001
Location: Houston, Texas
Posts: 1,071
Jim is right about the alternator light. If its bad, then the alternator will not start generating output. Good diagnosis Jim.
__________________
I got too many cars!! Insurance eats me alive. Dave

78 Corvette Stingray - 3k
82 242 Turbo Volvo - Manual - 270k
86 300e 5 speed manual - 210k
87 420sel - 240k
89 560sl - 78k
91 420sel - 205k
91 560sel - 85k
94 GMC Suburban - 90k
97 Harley Davidson Heritage Softail - 25k
00 GMC Silverado 1 ton 30k
Reply With Quote
  #11  
Old 11-27-2002, 11:36 PM
Registered User
 
Join Date: Oct 2000
Location: Lansing, Michigan, USA
Posts: 49
Hmm. The diagnosis of the alternator not "starting" sound like that could be it. But my light on the lower left hand side of the dash comes on when I set it on "glow." At least I think it is the alternator light. It looks like a little battery. That it what was showing when I had a bad alternator -- that light came on while driving. It is lit when I take the key out of the ignition and let it "diesel down" for a shut off.

Any other reason that the alternator would not "start"?

Thanks for the help.

josh
__________________
81 300D 250K (sold)
79 240D 200k
83 Volvo Station Wagon (282k)
Reply With Quote
  #12  
Old 11-28-2002, 01:12 AM
Mike Murrell's Avatar
Registered User
 
Join Date: Feb 2000
Posts: 2,351
Autozone should change the name of their "DuraLast" products to "QuicklyGone".

I went thru this with an American car about 15 yrs. ago. I forget how many times I pulled the thing off and went back for another.

Autozone's price is appealing; their quality is a whole 'nuther thing.

Bite the bullet and get a Bosch reman for your MB or a brand new one. Anything will be better than the crap Autozone sells.

My 2 cents.
__________________
Mike Murrell
1991 300-SEL - Model 126
M103 - SOHC
"Fräulein"
Reply With Quote
  #13  
Old 11-28-2002, 11:12 AM
dpetryk's Avatar
Electrons can do anything
 
Join Date: Sep 2001
Location: Houston, Texas
Posts: 1,071
Try another alternator regardless of the fact that the one you have now tests "good".
__________________
I got too many cars!! Insurance eats me alive. Dave

78 Corvette Stingray - 3k
82 242 Turbo Volvo - Manual - 270k
86 300e 5 speed manual - 210k
87 420sel - 240k
89 560sl - 78k
91 420sel - 205k
91 560sel - 85k
94 GMC Suburban - 90k
97 Harley Davidson Heritage Softail - 25k
00 GMC Silverado 1 ton 30k
Reply With Quote
  #14  
Old 11-28-2002, 12:35 PM
Moderator
 
Join Date: Jan 2000
Location: Maryland. USA
Posts: 180
JoshMB,

Bear with me as I lead into my point by way of example.

Over the years with Bosch Alternators I have noticed that they can fail to charge (worn out brushes on the voltage regulator) without illuminating the Light in the cockpit. So in my 1981 Volvo I installed a Voltmeter gauge. After start, the needle always went to 13-14 volts (where it should be for a charging condition).

At 175k miles, the factory Bosch alternator failed. As this was a daily rusty driver, I purchased an Autozone Duralast alternator for my Volvo. They are "cheap". And that is probably the operative word.

Mine exhibits the same behavior your's does. After start it shows about 12-12.5 volts (no charging). If I pop the throttle above 2000 rpm the voltage gauge shows that it is now charging. You may want to try the same thing. However, since I don't know how many rpm the alterantor is at with 2000 rpm at the crank, your rpm may be higher or lower to get it to charge.

I'm going to make a guess here. The Duralast design probably had cost as the top priority. That includes the regulator. The regulator provides an excitation function that gets the juice flowing. Mine requires more rpm to get going than does the OEM speced Bosch. I've test my theory on my three other Bosch based systems. After start, with no increase in rpm, there is charging voltage.

If the battery isn't being charged, then your running off the battery and it can not self charge just sitting there.

Please let us know if my experiences are yours too.
__________________
S, J.R. Brown
2000 G500 LWB Obsedian Black
2005 Toyota Tacoma Access Cab Off Road Sport
1993 Volvo 240 Sedan Anthracite
1980 450SEL Champange (owned it for 15 years. Great car)
1986 280GE LWB Anthracite (Sold it and kinda wish I hadn't)
Reply With Quote
  #15  
Old 11-28-2002, 12:36 PM
Moderator
 
Join Date: Jan 2000
Location: Maryland. USA
Posts: 180
JoshMB,

Bear with me as I lead into my point by way of example.

Over the years with Bosch Alternators I have noticed that they can fail to charge (worn out brushes on the voltage regulator) without illuminating the Light in the cockpit. So in my 1981 Volvo I installed a Voltmeter gauge. After start, the needle always went to 13-14 volts (where it should be for a charging condition).

At 175k miles, the factory Bosch alternator failed. As this was a daily rusty driver, I purchased a Duralast alternator for my Volvo. They are "cheap". And that is probably the operative word.

Mine exhibits the same behavior your does. After start it shows about 12-12.5 volts (no charging). If I pop the throttle above 2000 rpm the voltage gauge shows that it is nwo charging. You may want to try the same thing. However, since I don't know how many rpm the alterantor is at with 2000 rpm at the crank, your rpm may be higher or lower to get it to charge.

I'm going to make a guess here. The Duralast design probably had cost as the top priority. That includes the regulator. The regulator provides an excitation function that gets the juice flowing. Mine requires more rpm to get going than does the OEM speced Bosch. I've test my theory on my three other Basch based systems. After start, with no increase in rpm, there is charging voltage.

If the battery isn't being charged, then your running off the battery and it can not self charge just sitting there.

Please let us know if my experiences are yours too.
__________________
S, J.R. Brown
2000 G500 LWB Obsedian Black
2005 Toyota Tacoma Access Cab Off Road Sport
1993 Volvo 240 Sedan Anthracite
1980 450SEL Champange (owned it for 15 years. Great car)
1986 280GE LWB Anthracite (Sold it and kinda wish I hadn't)
Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On




All times are GMT -4. The time now is 12:57 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2011 Pelican Parts - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page