2001 ALH Battery Drain Found!

Looney2uner

Well-known member
Joined
Jan 19, 2008
Location
Moe Rael Kweebecque
TDI
2001 Jetta
My 2001 Jetta TDI with 420K Km was draining the battery completely overnight, even with a charger on it showing approx. 3A going into the battery. I bought a $60 DC clamp milliammeter from eBay (model SE02, which died after a week, but showed a 5A drain while it worked). Pulling all the fuses did not stop the drain. I now suspected the alternator diodes (booster cables were reversed when jumping another car, d'oh!)

It dawned on me (at dawn) that a 5A drain equates to 60 Watts of heating going on somewhere. This morning, cold engine, warm alternator = problem located.
An all new 120A unit with new clutch pulley installed (from eBay seller california_alternator_starter, $144) will be going into my favorite car ever.
 

whitedog

Veteran Member
Joined
Jul 12, 2004
Location
Bend, Oregon
TDI
2004 Jetta that I fill by myself
I like it. Sometimes we need to throw away the electronics and use our hands and brains to find problems. I have done the same thing finding high pressure leaks on hydraulic systems. A cold machine with a hot spot points right where the leak is.
 

GenMan

Veteran Member
Joined
Dec 10, 2009
Location
Grandville MI
TDI
2011 Golf (aka Phil) 4dr 3 pedals Candy White
My 2001 Jetta TDI with 420K Km was draining the battery completely overnight, even with a charger on it showing approx. 3A going into the battery. I bought a $60 DC clamp milliammeter from eBay (model SE02, which died after a week, but showed a 5A drain while it worked). Pulling all the fuses did not stop the drain. I now suspected the alternator diodes (booster cables were reversed when jumping another car, d'oh!)

It dawned on me (at dawn) that a 5A drain equates to 60 Watts of heating going on somewhere. This morning, cold engine, warm alternator = problem located.
An all new 120A unit with new clutch pulley installed (from eBay seller california_alternator_starter, $144) will be going into my favorite car ever.

Good job, love it...
 

Looney2uner

Well-known member
Joined
Jan 19, 2008
Location
Moe Rael Kweebecque
TDI
2001 Jetta
Just wondering.
Is it possible to replace the bad diode or diodes.
Yes, you can buy the voltage regulator assembly separately. But, in my case, it had 420,000 km on it (brushes and slip rings near the end of their life?) and the clutch pulley was seized also. So I would have had to buy the clutch pulley removal tool also. For me, easier this way.
 

Looney2uner

Well-known member
Joined
Jan 19, 2008
Location
Moe Rael Kweebecque
TDI
2001 Jetta
I have no idea what Amperage the original alternator was rated at, but I had the choice of buying a 90, 120, 140, and even a 170 Amp replacement. If they're all in the same sized housing, what is the difference between them? Thicker windings, brushes?? Since the internal fan cannot be up-sized much, the high-Amp ones must really get hot at full output.
 

Looney2uner

Well-known member
Joined
Jan 19, 2008
Location
Moe Rael Kweebecque
TDI
2001 Jetta
UPDATE

Uh, oh. This morning I did my touchy-feely test on my alternator and it was COLD! My original, hopefully correct, diagnosis was that my battery drain was through bad diodes in the alternator. Today the car started like it had a fresh battery that did not drain overnight.

So, my question to all you experts out there is: Can a bad alternator/diodes be intermittent?

I've had this problem for months and there were occasions when the car started the next day without being on a charger. The new, replacement alternator is already on it's way to me, so it will be installed regardless of what's causing the problem. I can't think of anything that would drain the battery and also keep the alternator nice 'n warm other than bad diodes.
 

NarfBLAST

Top Post Dawg
Joined
Mar 3, 2002
Location
Waterdown, Ontario, Canada
TDI
2001 Golf 5MT
I assume these alternators have brushes if so these could be worn or have a buildup of carbon that arc but only in certain positions? Just a theory.

I really like the hands on diagnosis.
 

03Springer

Veteran Member
Joined
Mar 4, 2003
Location
Southern Nevada
TDI
2003 Golf GL+ 2013 A3 TDI
Here is the thread on replacing the voltage regulator with part number. Having worked on avionics on military aircraft for 30+ years all I can say is one minute it is working fine and the next it isn't. That is electronics, if it gets too hot or cold, solder joints open, components are affected etc. You won't have to pull the alt if you replace your regulator but if the alt has more than 150K on it then it's cheap insurance to replace it in the comfort of your driveway/garage as opposed to leaving you stranded on the side of the road when it's raining. My .02 cents!

http://forums.tdiclub.com/showthread.php?t=317389&highlight=voltage+regulator+part+number
 

Lug_Nut

TDIClub Enthusiast, Pre-Forum Veteran Member
Joined
Jun 20, 1998
Location
Sterling, Massachusetts. USA
TDI
idi: 1988 Bolens DGT1700H, the other oil burner: 1967 Saab Sonett II two stroke
... Sometimes we need to throw away the electronics and use our hands and brains to find problems. I have done the same thing finding high pressure leaks on hydraulic systems.
:eek:
PLEASE tell me that you don't actually use your hands to locate high pressure hydraulic leaks! That action can kill you!
 

Looney2uner

Well-known member
Joined
Jan 19, 2008
Location
Moe Rael Kweebecque
TDI
2001 Jetta
Yah, I knew the voltage regulator could be changed and solve a bad diode problem, but with over 420,000,000,000 mm on the odometer combined with a seized pulley, it would not make sense.
The intermittency (is that a word?) could indeed indicate either a loose solder joint or a cruddy spot on the commutator where an equally cruddy worn brush happened to rest when the engine stopped. I just hope to heck that it's not some mystery stuck relay somewhere. The seized pulley alone is reason enough to replace the whole thing, considering the high millimeterage on the unit.
Of course I'll comment when the job is done. Thanks for all you guys' input.
 

RSMS

Vendor , w/Business number
Joined
Dec 1, 2011
Location
Clearwater,FL
TDI
04 T-REG V-10 as a driver but too many others to list and always changing
Lug nut....I've seen someone who had hydraulic oil from a high pressure fitting failure penatrate his finger. It was a very small entry wound that could easily be brushed aside but luckily we new the damage this could cause. The emergancy room basically opened his finger up like a fillet to clean out the tissue damage. It is a very serious injury that can cause amputations or even death as you said. Back on topic, We've had the same issue and fix in the past. I think you made the right call on replacing instead of patching for what it's worth
 

whitedog

Veteran Member
Joined
Jul 12, 2004
Location
Bend, Oregon
TDI
2004 Jetta that I fill by myself
:eek:
PLEASE tell me that you don't actually use your hands to locate high pressure hydraulic leaks! That action can kill you!
Not external leaks. Internal leaks.

In other words, not OOG leaks (Oil On Ground)

but rather OLI leaks (Oil Leaking Inside)

You are right though. If oil is leaking out of a high pressure hydraulic system, don't use your hands to find the leak.
 

climbtheplanet

Well-known member
Joined
Aug 22, 2008
Location
Boulder, CO
TDI
2001 Golf
I have no idea what Amperage the original alternator was rated at, but I had the choice of buying a 90, 120, 140, and even a 170 Amp replacement.
All of my research over the past few days has found that you are correct in buying the 120A. Took mine out yesterday and it was the OEM part from 2001 and is 120A.
 

Looney2uner

Well-known member
Joined
Jan 19, 2008
Location
Moe Rael Kweebecque
TDI
2001 Jetta
All of my research over the past few days has found that you are correct in buying the 120A. Took mine out yesterday and it was the OEM part from 2001 and is 120A.

Thanks, that's reassuring.

Just like a toothache that disappears on the day of the dentist appointment, my battery has not drained once since I hit the "pay now" button on my eBay
alternator purchase. It's as if the old one "knows" that it's been bad and is trying to change it's ways. :p
 

2ManyKMfor1Tank

Veteran Member
Joined
Feb 25, 2009
Location
Grand Valley, ON
TDI
2000 Jetta
Thanks, that's reassuring.

Just like a toothache that disappears on the day of the dentist appointment, my battery has not drained once since I hit the "pay now" button on my eBay
alternator purchase. It's as if the old one "knows" that it's been bad and is trying to change it's ways. :p

Just like when I first started browsing these forums, I'd read up on a type of problem these cars typically encounter, next thing you know my car is doing it as though it had ears.
 

jdross440

Well-known member
Joined
Mar 1, 2009
Location
Arkansas
TDI
2002 Jetta
Mine has started doing the same thing, drain at night. It has done it 3 nights in the last week. I'm on a trip 1000 miles from home. I put a new (rebuilt) alternator in about a month ago as the clutch pulley had failed (wouldn't engage).
 

Looney2uner

Well-known member
Joined
Jan 19, 2008
Location
Moe Rael Kweebecque
TDI
2001 Jetta
No more drainage problems now with the new alt. I killed the battery also with the frequent complete discharges. I built a 120 Volt de-sulfater and pretty well resurrected the battery. I put a motor-run capacitor and a bridge rectifier into an old computer power supply case. With 120V pulsed D.C. charging the battery for a week (and adding 3 liters of distilled water to the cells, um, maybe that lack of water helped kill it), the battery has renewed vigor, but I am digressing.
 
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