Subpage of MembersPage/MarcellGal/PowerAndTraction
This engine has a 110A Bosch alternator, driven by the outer V-belt from the 3-belt crankshaft pulley.
Alternator connections
- a THICK red (obviously positive) wire with 8mm ring connector. I cleaned the connector surface before securing. In my install +12V (always live) coming from the starter mains. I hope this is right
- the alternator body must be the ground
- there is a small ring-connector, wire is broken off on my engine harness. Not sure what this is about. Maybe to disable charging during heavy acceleration ?
- I used to have some small-current (5..6 pin) connector on the alternator (on my cars earlier, at least where I checked). Maybe for the charger-control, or to disable charging at full throttle.
I guess the charger-control is integrated inside the alternator in these audis.
MembersPage/PaulF - Most smart alternators that I have dealt with fail safe to an output voltage of around 13.8V. Usually it is to allow the charging voltage to be lowered at idle to help pullaway. It is also used for feedback to the ECM as to the load on the alternator for torque adjustment.
There is some charging when engine running, 13.7V
- higher than 12.5V means charging
- but less than 14V means the charging current might be low. Most likely the failsafe mode of the alternator.
It charges somewhat .. maybe suboptimal, but it works.
I think I found a wire with ring connector that could be alternator excitation. I heard that this is connected to VBATT+ through a small indicator lightbulb. I heard that this indicator (on the dash?)
- lights up bright if alternator stops (alternator belt lost)
- lights up dim up if there is overcharging (???)
MembersPage/ZoltanAlmasi - The ring connector wire come from the instrument cluster's charge indicator bulb. The bulb get 12V+ from the ignition key. This circuit needs for the alternator to proper inducing. Without bulb or when this circuit is open, the alternator don't induce up or just very slow.
Alternator belt
I cannot seem to get a proper drive to the alternator.
- The orig belt was squeaking
- mostly during gearshifts, and when the big fan starts
- we applied a new belt that worked for a few days, than overturned and got rounded and burnt (became useless, except maybe for lifting ;-)
- the orig belt appluied again, worked for a few months
- the belt was lost on 2007-10-10. Because of lack of immediate charging indication, I noticed it a bit late: the dash-computer only warned when VBATT started to drop, and it took some more time for me to take it seriously (first I thought it was a bad indication).
- I installed the spare belt (920mm long, not sure about width, IIRC 10mm) at the roadside (I had it in the trunk, with good prediction it would be needed). I think I got the tension right. It was squeaking a bit, but with the almost drained battery I had to keep it running (it might not have supported another cranking), and I lost the belt again, in about 10 mins.
WTF is happening ?
- bad beltsize ? 9.5 or 10mm or some other size needed ?
- bad tension ? I think I can get the tension right, but ... who knows...
- slippery pulley? The valve-drive simmering seems to spread a very small amount of oil (which sucks, I paid for brand new simmerings when engine was rebuilt a few months ago). The alternator V-belt pulley gets a little wet with oil, I'm sure this is not very good. The squeaking is not surprising.
So after I lost the alternator belt (snapped or jumped off ? dunno) TWICE: Than in a rush to find parking place downtown, I stuck a concrete and killed the bottom oil-cap and the right-ear of the charge-cooler broke.
It was a really bad combination:
- wheel in hole
- concrete at worst place
- while running without charging
- rush to find parking place downtown
- I parked at the neighbor place last week which was perfect
- the stupid concrete at this place was really naughty
- it was also dark, and running at a crazy speed (for parking), I noticed the danger too late
- typical Titanic situation ;-)
Oil-change was about time anyway, and I have a spare bottom-oil-cap to install, and we ordered 2 gaskets already. But the broken-off charge-cooler ears are no fun, removing the cooler and welding Al has its costs.
Ghost current
When ignition is off, current draw from the alternator is 0.37A. This means I have to charge with a battery charger if parking more than 2..3 days so I can start the car after.
What draws the ghost current ?
- some light in the trunk or under dash or glovebox ?
- maybe some small lights like at the pushbutton of the automatic windows ? (unlikely: they work without ignition, but lights are apparently only lit when ignition is on).
- alternator ?
- maybe connecting the excitation wire helps ?
- radio ?
- immobilizer ?
- central locking control system ?
- cabin-heating or climate system ?
- there is some strange box under the glovebox with appr 10 color (thick, 1mm2 or so) wires going to the mid-box, I have no idea what it does
I guess I have to pull fuses 1 by 1 to find out where the ghost current goes. Isn't there a hierarchy so I can test a larger number of subsystems with less steps ? If fuses are arranged in a tree topology, this would be nice. But I guess there is the main fuse, and 20+ "neighbor" fuses under it.