Cold Start (-20 degC, -4 degF), Good Battery, Good Alternator, Low Parasitic Draw

Hi guys,
How's everyone doing in this cold? Here's another cold start issue for you to crack. The car is an 2003 Jetta TDI, five speed, 343,XXX kms, 214,XXX miles.

Symptoms:
Numb fingers, face... Below -20 degC, -4 degF, clutch pedal returns to position slower than normal.

The OEM battery (80 Ah, the top prints 380 A DIN, 640 A EN/SAE) was tested good (less than a year old, 627 CCA), I even have a second battery (Energizer Max PG-700N, 95 Ah, 830 CA, 700 CCA) from the junkyard that was apparently load tested before I bought it. I have them hooked up as if I am receiving a jump.

When I try to crank it, the engine turns over by a fraction of a second, not even one revolution, then the dash went out, door unlocks.

When I hooked up the voltmeter it shows 12.43 V for the warm backup battery, 11.79 V for the cold original battery. When glowing, it drops to about 10.5X V, when cranking, it drops below 7.5X V.

No start with two load tested batteries! I am wondering:
1. Is the OEM battery (80 Ah, the top prints 380 A DIN, 640 A EN/SAE) the right one? I am hoping the dealer didn't give me a gas model's battery.

2. The clutch returned a bit slower to the starting position than normal, I know I have the car in neutral, probably won't affect starting that much. But would the clutch stick? I am currently using some 18-month-old ATE Super Blue Racing Fluid which advertises its 3-year changing interval. I don't race it much anymore, would it have absorbed too much water and froze?

3. Does it seem like the starter was drawing too much power and the voltage dropped too far? Perhaps the starter is shorting out? It doesn't happen when it is warmer. Maybe it turns over slower when it is cold and gives the starter a chance to short out?

I am currently warming my OEM battery and charging it inside. Let's see if it will start with both batteries warm.
Could you guys give me some inputs please? Anything would be appreciated.
Cheers,

Jason

Oh by the way, I measured the resistance between the negative battery post and the ground about a month ago, the connection was good. I think I also measured the positive battery post and the starter, the connection was also good.
I don't think the situation has changed since the cold start problem has been going on since last winter.

Had the same issue, starter was the culprit.

hook up only the good warm battery as close to the factory cables as possible. anything below 12v is straight dead. hooking a good battery to a low voltage battery will kill the good battery in the process. the two try to equal eachother out. with a voltage difference that large, and temps that cold, its not gonna work very well. Even 12.47v isnt fully charged, a fully charged 12v battery should be at 12.6v

Can you get anyone to give you a jump and see what happens? starters will draw a higher amperage at colder temperatures, and also draw higher amperages as voltage drops. Ideally, when cranking, you want to see 9-10v.

I feel that you have a compounding issue here stemming from the factory battery being below 12v, the cold is adding to the issue. remember to use the shortest jumper cables possible, and the largest gauge you have. If you can eliminate the original battery you'll be in much better shape.

and as far as the clutch, my 01 does the same thing below 0 degrees, fluid moves very slowly at those temperatures, mine goes back to normal after a few gear shifts.

I had been noticing my car (03 Jetta 5speed w/ 99k) was turning over a little slower as temps dropped below 40F.
I had the battery and alternator tested and they looked good though.

A couple weeks ago when it was 5F it would turn over but not near fast enough to start. A booster pack did nothing to help the issue.

Replaced my starter with reman unit from IDParts and it now it cranks MUCH faster and easily started this morning at 8F.

I had always thought starters just either worked or didn't but I learned that's not always the case. I've read of several others on here who also had slow cranking due to a worn starter.

a bit off topic does it help to let the glow plugs do their thing more than once before cranking or is that just a bad idea, -24 here and starts on first crank 2002 jetta
Most likely battery issue

Both your batteries are pooched!!! Playing with two suspect batteries is contributing to your mis diagnoses. One GOOD battery is more than adequate at minus 30C. Untill you fix this , any discussion on defective starters a premature.

And... you guys are probably all right. The junkyard battery died, over one night, it went from 12.74 V to 10.59 V with nothing hooked up, sitting in the warm kitchen, nothing crazy. The OEM battery should still be good though. I think mine just has low cold voltage. It sits at around 12.3 - 12.5 V (hooked up, outside) depending on the temperature. After bringing it inside, the voltage comes back up to 12.76 V.
I didn't get a chance to clean or swap the starter this past weekend, I'll try to fit that in this Thursday. I was told that it will benefit from some cleaning at this stage anyway (344,XXX km). I'll keep you guys posted.

So I just cleaned the starter last night, it was much easier than anticipated. The good news is that the starter seem to be in good condition, just a bit of dried up grease in the gears, the bad news is that I don't know if that was causing the hard starts. The weather seem to be warming up so I probably won't be able to test it until next year. I hate to put it off.

I'm experiencing the same with my 2000 Beetle. Same condition at -14F charged battery and started. Starter seems good and ground. Tracking a possible parasitic drain, but can't find one yet. I have some gauges wired in might be there. Let me know what you find out. Same voltages.

What's the current draw when the car is locked and armed? Unhook battery negative terminal, attach multimeter (if you use one, be sure to have 10A selected and use the correct post on the multimeter before attaching, or else it starts smoking!), close hood and all doors, lock with key or remote. For your year, you can probably wait only about 1 minute before it goes to sleep mode, the TSB stated current should be lower than 0.04A or 40mA.