Blinking battery light

Hi guys.
Having a problem with my charging system. Couple weeks ago, on my way to town, my battery light stayed on all the way. I went straight to the electrician, who ended up servicing the alternator, including rewiring the rotor and new brushes. He also changed the slip rings.

The following week, I noticed the battery light flashed every time the car was turned off, or I slowed down. A couple days, in addition to that, sometimes after a ride over corrugations especially, the light would pulsate at idle.

I took it back to the electrician who tested the system and he didn't find any problem. What could be the cause of this ?

Assuming you leccy is competent sounds like a loose wire .

X2 with the loose wire or connector. After inspecting the wiring loom, battery connections and alternator lugs, do the knockometer test. Have someone sit in the driver's seat with the engine running. Use the handle of a screwdriver to tap the loom and back of the alternator (don't belt the hell out of it). Be bloody careful not to get caught up in any moving parts, or to short out anything.
Hopefully the light will flash if you tap the right place. Also check the ignition switch.

If the warning light is pulsating regularly at idle it might have a weak diode or possibly a short in the stator winding in the alternator.

Is the alternator making a growling type noise? What happens to the warning light if you increase the electrical load? Turn interior fans on high and put high beam on.

Thanks guys. He is not the most competent electrician, to be honest. Kinda suspect something is loose too as it doesn't pulsate at idle all the time. Just after a drive on corrugations. When I turn on the light, the pulsating stops. Going to try your advice Mudnut. If that doesn't work I'm going to have to pull it done as it may be, as you say Yendor, a weak diode or the stator winding.

If your not confident in what the sparky has done it can lead to a lot more fault finding areas , the obvious is voltage output , earthing etc etc .
I know my GQ wiring is getting old and brittle , mainly in the engine bay .