Alternator Or Battery?

1. Matt-T Established Member Joined: Oct 2010 Rednal Posts: 1943 Vauxhall Vectra VW Golf Mk4 Honda Prelude

   #1 7th January 2011, 22:11

   I was in the car earlier waiting for someone. Car was idling.
   
   I had my window down abit, so i put it up and noticed dash went slightly Dull...
   Then i turned heater from 2 to 4... car didnt seem to like it much engine revs went up obv due to the load i put on the system. But also headlights went dim....Its never done this before.
   Im guessing the battery is buggered, mate said could be the alternator
2. user_46471 Infrequent Poster Joined: Aug 2010 burton on trent Posts: 239 v plate vtr silver

   #2 7th January 2011, 22:13

   i would say alternator as that provides the electric once the car is running
   
   get a battery from some else's car and see what happens
3. user_31412 Established Member Joined: Feb 2009 ★ West / North Yorkshire ★ Posts: 1653

   #3 7th January 2011, 22:16

   Most likely alternator as it was running. Get a meter on it and check the voltage.
4. Matt-T Established Member Joined: Oct 2010 Rednal Posts: 1943 Vauxhall Vectra VW Golf Mk4 Honda Prelude

   #4 7th January 2011, 22:18

   I did this.. was reading 13.7v on batt.
   alternator is less than 6 months old
5. user_31412 Established Member Joined: Feb 2009 ★ West / North Yorkshire ★ Posts: 1653

   #5 8th January 2011, 01:41

   Should be reading ~14.4 volts. If you got the alternator new or as an exchange id take it back cos you'll probably have a 12 month warranty.
6. tom_lloyd_4 Regular Poster Joined: Nov 2010 alton hampshire Posts: 348 97 mk1 vtr 85 LR 90

   #6 8th January 2011, 01:57

   still could be the battery if it has a bad cell it will sap power from the alternator take it to quick fit and get them to test battery and alt
7. user_20080 Saxperience Hardcore! Joined: Dec 2007 smurfland. Posts: 17346 Ex saxo owner.

   #7 8th January 2011, 09:57

   Take it to Halfords ask for an alternator and battery check,sounds to me like the alternator is faulty.
   
   Steve.
8. Matt-T Established Member Joined: Oct 2010 Rednal Posts: 1943 Vauxhall Vectra VW Golf Mk4 Honda Prelude

   #8 8th January 2011, 11:31

   Thanks Peeps,
   Had a look this morning, was still the same. So rather than fit the golf battery i got a new one from halfords. Fitted it and so far. Looks like problem solved. Running voltage across the battery is now 14v.
   Give it few days if goes back the same will take this alternator back and get a new one.
   
   Cheers
9. willsy West Midlands Joined: Nov 2005 Nuneaton (West Mids) Posts: 13835 '64 Volvo V40 R’Design, '89 Ph1 309 GTi, ‘97 Mk1 S

   #9 8th January 2011, 12:14

   Before you change battery and or alternator you should get the tension checked on the alternator belt first.
   
   If this is slack then thatll cause similar effects to what you've been having also. If the alternator was struggling to keep the battery charged then the red battery light should be up on the dash.
   
   Check te belt first anyway, does it sometimes squeel a bit on cold mornings when first starting the car?