[Vwdiesel] Really wierd stating problem

[Val Christian]

Gang,

About 60kmiles ago, while having a warranty replacement of a 
glowplug, my 03 TDI Jetta started "starting hard".

I've replaced glow plugs, probed current flow to each plug, 
checked/adjusted/checked/etc timing, measured starter draw,
load tested the battery (many times), measured voltage drop to
starter, checked shudder/egt/etc, spray patterened injectors,
compression checked (525/530/530/530 last time), verifed 
flow in fuel filter, reblended oil (no 2 and No 1 mixes), 
use 5W40 oil (fresh), etc.  Over all the miles the problem
has not getten better, just slightly worse.

Randomly, the car won't start at all when it is cold, usually
without boostering or jumping.  Yet, the load test is good.
Group 94 battery, 650 CCA, 810 CA whatever that really means.

Today, 4F wx, I had a smart charger on the battery overnight.
Voltage 13.3, with charger off.  Started glow cycle, and 
cranked.  Slow crank.  Freshly charged battery.  Fresh oil.
After 20 seconds or so (two tries) the battery would not 
crank.  

At that point the smart charger was pumping 25 A into the battery,
so i went inside, and came out in 30 minutes.  Initiated the
start cycle, and voila, it started just like when it was 
a new vehicle.

So I'm now thinking that the battery is intermittently bad.  
Anyone ever have a similar experience, or heard of this kind of 
failure?

Val