1990 80q battery problem

[Ti Kan]

Cody Forbes writes:
> You seem to have a draw on the battery, and a test to see how large that
> draw is usually can help diagosis. Disconect your battery positive and
> connect a multimeter between the positive terminal and the positive cable,
> with the multi meter set on amps. something in the area of 1amp, maybe a tad
> more is aceptable (power being drawn by ECU, radio, and clock to save
> settings), but much more then that means you have another something draining
> your battery. If its over 10amps I would start looking at your alternator,
> you may have gotten a defective unit, or you may have a short in the
> positive between the alternator and the battery.

Cody,

Your suggestion generally good, but I would offer the following
modifications:

1. Measure the current on the *Negative* battery cable instead of the
   positive.  This is safer, because when you're messing around with
   the battery cable, if the positive side is to accidentally touch
   the chassis ground, you could cause a nasty short circuit.  No such
   worry while working on the negative side.

2. The multimeter must be able to handle a fair amount of current.
   Many meters don't.  For example, my Beckman has a max rating of
   only 2 amps.  While there shouldn't be anywhere that much current
   flowing with ignition and all accessories off, if there is a bad
   current draw somewhere, you could risk damaging the meter (or
   blow a fuse in the meter), or melt your meter's probe wires.

3. 1 amp is *too much* current for the engine off/all accessories off
   condition.  I would say that you shouldn't have any more than
   one tenth of that, or 100mA.  The ECU shouldn't be on while the
   ignition is turned off.

Regards,

-Ti
2003 A4 1.8T multitronic
2001 S4 biturbo 6-sp
1984 5000S turbo
1980 4000 2.0 5-sp
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