My FRST has a problem with charging. I have had my alternator tested which has proved that it is working as it should be.

The alternator charges no problem when there is no load on the battery ie lights etc turned off but at night when the lights are on and say i've got the indicators flashing the battery light on the dash board lights up faintly and say I touch the brake pedal which switches the brake lights on the battery light gets stronger and goes bright red should I put the main beam on or the wipers on. I bought a tester from Halfords today and it does show that the alternator does charge with no load but there is no charge getting to the battery when the above are switched on.

I think the above makes some sense but does anyone know what the problem could be and how to put it right? Any help will be appreciated.

 

alternator's knackered

 

check the wiring going from alternator to starter to battery also earths etc

if all this is ok then alternator is kanckered

 

put a multi meter on batt terminals it should be about 12 v dc,start engine and rev car abit while reving it check meter it should increase to about 13 or 14 v ,if it does this ok then you need to get batt tested,have you checked water in batt o is it sealed

 

I havent checked the water level in the battery but could this be the problem. I've got cossie management on the fiesta and got a secs monitor fitted. This does show a starting voltage of about 12v and today was showing 13.5V when the engine was idling which drops to under 12v when the lights etc are switched on.

 

sounds like your batt,might be worth getting a drop test done on it,most garages will do it for free,winter is coming,heaters on etc

 

What could cause the battery to fail. I bought a brand new battery from Halfors in April 2005 with a 4 year warranty. So its only been fitted for 18 months and the car was off the road for 9 of them. Would not having enough water in the battery also cause it to fail?

 

yes i fitted one six months ago on a customers car and it failed on sat sometimes you get a duff cell in them

 

Thanks, I'll get it checked out and get a replacement under guarantee from Halfords if its faulty.

 

just re read your 1st post it could also being caused by a slipping fan belt!

 

think its time to get a merc now mr kameou