Dash needles twitching

[gingdave]

youtube dot com /watch?v=Q5VlBs2bi6E

Hi,
Whilst driving my dashboard needles occasionally all start twitching together, see video above.
All 4 will drop a bit and then return to where they should. This will keep happening for a while and then everything will go back to normal.
This happens every so often and sometimes the battery light comes on while it's happening.
There doesn't seem to be any other obvious issues with the performance of the car.
One thing I have noticed is that sometimes when I fully close both electric windows at the same time, when I let go of the buttons all of the dash needles briefly dip.
Battery was under warranty so kwikfit guys checked it and the alternator and said they were both fine.
Any ideas?
It's a '04 206 1.4 petrol.
Thanks in advance
Dave

[gingdave]

garage can't replicate problem. it was doing it when idling and on the drive to them. off to collect. f''king annoying

[Capncol]

I know you said it's been checked, but it does sounds alternator related. The charge is controlled by the ecu at that year.

[gingdave]

Thanks for the reply. Yeah I'm beginning to think so..... and it'd be easier for it just to get replaced and have some confidence in the car (until the next problem!).

The problem has come back since taking it to the garage.
Took it out yesterday and everything was working fine.
I got the multimeter out when i got back and got the following readings across the battery posts:

Engine off. 12.35v
11.65v high beam, hazards
Then 12.22v

Engine on idling 11.9v
Revs 11.86v
Idle with load (high beam, hazards, heater) 11.21v
Revs with load 11.0v (battery warning light came on at this point)
Idle no load 11.65v

+ve Alternator to -ve battery 9ish, jumping down to 3v to 5v?

Tried ohms with -ve disconnected, Alternator to battery +ve but no reading.

When I tried this last week whilst the problem was there (dash needles twitching when revving) the readings across the battery posts when revving with lights etc on was 15.6v. At that point I thought it might be a over charging alternator (risk battery etc being fried) but after yesterday it seems that the alternator isn't working at all.

If a garage did these tests do you think they'd just get on and try a new alternator? or see if there's a problem with the the alternator/battery circuit?

Does this rule out battery earth strap problems? Not much time at the moment to get my hands dirty due to young baby.

Thanks for reading this far. Any advice appreciated.
Cheers. Dave

[Capncol]

Engine on idling 11.9v
Revs 11.86v
Idle with load (high beam, hazards, heater) 11.21v
Revs with load 11.0v (battery warning light came on at this point)
Idle no load 11.65v

That's not charging at all. Check all battery and earth connections carefully. If that all checks out, it's new alternator time. Make sure you follow the battery disconnection method shown on this site.

[gingdave]

thanks for the reply.
I've been away but will get it booked in asap.
Can only hope the garage follow the correct reset procedure but will do it myself when I collect.
I was really surprised by how low the readings were as I was convinced it was overcharging.

[gingdave]

New alternator fitted yesterday. BSI reboot just in case. 60 mile drive with no symptoms.

Engine off. 12.44v
Engine on idling 14.25v
Revs 14.28v
Idle with load (high beam, hazards, heater) 14.09v

seems ok. fingers crossed.
cheers

[Capncol]

Well done, and thanks for the feedback.