Any alternator specialists on here?

[KS Carrera]

Here's the problem:

Alternator is SEV-Motorola type with external regulator. Alternator was rebuilt and regulator is new.

Battery goes flat after a day or so of the car just sitting in workshop. I mean flat as in nothing, zilch, nada. Clearly a voltage drain somewhere. Recharge battery and remove negative strap – small spark from battery terminal to strap shows current is being drawn somewhere, which is confirmed with a voltmeter. With ignition off, remove all fuses one by one to see if there is a circuit with a short somewhere. Nothing. Finally trace the problem to the D+/61 terminal of the regulator – which connects to the D+/61 terminal of the alternator. If I unplug the lead from the alternator, there's no spark at the battery terminal. Check with a voltmeter and sure enough there's 12v coming from the D+/61 terminal of the alternator all the time – engine and ignition off.

Surely there should only be 12v (well, a bit more, really) available at this terminal when the engine is running?

Any ideas? To me seems like a problem with the alternator (diodes?).

[304065]

Bad voltage regulator. Regulator is "new" what type is it? It's very important to have the same manufacturer of alternator and regulator-- particularly because the Motorola and Bosch types are differnent (some model Motorola have only a single "trio" diode instead of 3, and the "set-point" or the level of current to the field to produce a corresponding voltage output is different.

A few more diagnostic steps.

1. What is battery voltage with engine off, measured at terminals?

2. What is voltage with engine running above 3000 RPM?