All lights intermittantly flickering

Hi,

I wonder if any of you can help with a problem I have been having with my 2003 Chrysler Neon.

Basically, when I am driving at night with the headlights on and the electrical load on the system changes (by turning rear headed windscreen on/off, or putting the indicator on/off) All the lights flicker for a few seconds.

After a few seconds the flickering always stops.

At first I thought the rectifier or voltage regulator must be on its way out, however yesterday I did a few experiments with a voltmeter and found that at idle the system voltage is 13.9 but the resting voltage of the battery is only 12.1 Volts, and the battery is the origional factory fitted one (over 4 years old now)

Also the flickering does not happen during the day (I can tell from the backlit odometer) it seems to be related to the load the system is under.

Could it just be the battery? Anyone experienced anything similar to this?

if the battery only has 12.1 after being left overnight then it is either not being charged enough (check by charging from a battery charger) or it is very worn out. A rested, charged battery should have 12.7 or 8.

Both those voltages seem to be a little on the low side, it could be that you need a new battery, it could be the alternator or it could be a bad earth causing excess resistance in the system.

I'd agree both are low- as mrcheerful said i'd expect more. I'd do the following (in order):

1. Check/clean battery terminals
2. Check/clean earth straps
3. Check/clean alternator connections
4. Charge battery with a charger overnight and redo voltmeter checks
5. Get the battery load tested, replace if duff
6. New alternator brushes/recon alternator

When checking the connections, be aware that they can be clean looking and done up tight and still give bad connectivity - I've had an earth strap like that.

You need to unbolt it, give both sides a light sanding then rebolt it to make certain. Cover it in vaseline or some other waterproof gunk to keep it in good nick for a long time.

I used to think you should gunk it after doing it up but somebody on here convinced me you could get better results covering the contact zone with gunk then bolting it up - but I can't remember why it worked better...?