Headlights dimmer when accelerating?


T

talan

Member
Joined
Mar 8, 2010
Messages
37
Strange problem.

When I'm accelerating, lets say throttle position 30% I can tell the headlights are dimmer because when I back off the throttle or decelerate I can see the headlights are brighter (no brake applied).

Anyone have/had a similar issue?
 
That's easy! don't turn on your headlights. :lol::lol:
Have you checked your altenator with your headlights off & on to see isf there is a significant drop in voltage that would cause the lights to dimmer?
 
Yeah i will hook a voltmeter up. What i also noticed was if i have my air con on the dimming does not happen.
 
Right'o, have had a play with the multimeter. Results as below:

- Car off: 12.1v
- Car running and no electrics on: 14.4v
- Car running, high beam on, A/C on, demister on, radio on loud: 12.7v
- Car running and pulled -ve terminal off battery with high beam, A/C on, demister on, radio on loud: 10.6v

What you guys reckon? Alternator?
 
OK found the problem.

It my alternator belt wasn't tensioned to spec . This makes sense because when the car is under load the belt slips. Tightened it back up and now reading 14.1v with all the power draining electrics on. Alternator is in good condition. Thanks for your suggestions!
 
I've got a similar problem too, when the car is sitting and I put the windows up and down the headlights dim aswell. Do you think it is my alternator belt too?
 
Ok i spoke too soon. Tightening the alternator belt has gotten rid of the votage drop under load but lights still dimming when under acceleration. Hmm...
 
check for play in any of the pulleys and check for life of the Alternator belt, for all it costs for a belt id give that a try aswel, the older the belt the more it sinks into the pully so less grip and when you give it a rev the extra speed could make it slip ( these are all assumptions :p ) kammy mines does that aswell im sure its just until the altinator starts to up the volts back into the battery because your taking more out with lights and windows
this might not make any sense as im completely shattered :)
 
12.7 v is way to low for the car running and under load needs to be between 13.8v and 14.8v ish the alternator is prob knackered also change the battery see how you get on :)
 
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