My daughter recently reported her Cee'd lights were flickering a bit, both dashboard and headlights. So I took it to my friendly mech who measured the current across the battery and it was below 12v so he said alternator.
I found a cheap reworked one (£79) on eBay and it was fitted and worked fine for a week or so but now the same symptoms have arisen. Mech has measured it a 13.4 volts max.
The people are going to swap the unit for me but are dubious that t's the real problem. They said they'll test the new one and the one I return, to assist me rather than make a point. They do sound like they know what they are talking about!
Hmmm OK thanks. I'm hoping it's not a wild goose chase with the alternator but I fear it might be. Mechanic was muttering about voltage regulator but ehe said that's part of the alternator.
I would be looking for a charging voltage of around 14.2 volts. If the replacement alternator still gives a low voltage,then you need to look at any volt drops in the system .Alternator to battery positive and also any drop on the neg line from engine/chassis to battery earth post.May also want to check the poly vee drive belt for any evidence of excess wear.These can lose grip and drive to the pulley system.
Many, many, years ago I had a similar problem on an Morris 1300. A section of the alternator belt had lost its "V" profile and was running on the backing strip. This did not cause an intermittent problem but made the lights pulse their intensity as the alternator slowed or stopped when the damaged section of belt passed the alternator.
The alternator has been swapped again and is now showing 14.2 volts. The mechanic didn't own up to doing anything else and said it was just a faulty one.