Re: Electrical Circus

Posted by humanpotatohybrid On 2024/6/25 15:06:15

You won't be surprised to hear that having a direct short can cause an overcurrent condition in the regulator. The reason why is because the generator voltage is proportional to:
- engine speed
- field magnetism
The regulator works by controlling the field magnetism, as you know. However the response frequency is only about 200Hz. This is normally not a problem since the battery will handle both voltage spikes and dips (turning off and on loads, respectively) until the regulator compensates.

If you have a direct short to ground then all the sudden you have, instead of 14V calmly charging your battery, you have 14V going straight to ground. A 30A generator will pump out a ton of peak current; but also the cutout relay isn't designed to break 14V or 30A. It's designed to open when there's basically no current flow occurring (= when there's little voltage across it).

So, while the cutout relay should be able to handle that current load closed, you have the cutout relay deciding to open because, directly after the current regulator relay opens and cuts power to the field coils, the generator voltage drops below 12 and the cutout relay opens in the middle of a short condition (11 or 12 volts is still shorted). Oh, and the inductance of the generator armature causes a massive voltage spike across those contacts.


So I would clean your contacts off (on all 3 relays) and try to re-calibrate your regulator. Might need a new one.