Worth changing alternator?

consumers_revenge

Hi,


Thoughts please


Have had the battery light come on yesterday and have had a half dozen instances of low revs over the last fortnight. ( focus 2000 1.8 zetec )


Soon as I pulled off the light went out but was on with little load other than indicators and lower idle revs


Been out just now and battery is 12.19v ( its only 7 months old )


CCA 10.36v


With car running no load 14.27v


Heavy load ( air con full/full beams/rear+front heater/fogs) drops to 11.6v idling @ 700-800


Heavy load ( air con full/full beams/rear+front heater/fogs ) drops to 12.35 idling @ 1750


Is it worth changing alternator?

Norman_Castle

have had a half dozen instances of low revs over the last fortnight.

Do you mean the tickover drops to below what it should be? The charge light might light up if the alternator is spinning to slowly.

patman99

If I remember correctley, the Ford Focus alternator is only one part of the charging system. The main part that monitors the voltage and ramps up/down output from the alternator is built in to the dashboard and requires the whole dash to be replaced if faulty.


Might be worth paying out for a full diagnostics check first before spending out on a new alternator and finding the fault is still present.

consumers_revenge

Norman_Castle wrote: »

Do you mean the tickover drops to below what it should be? The charge light might light up if the alternator is spinning to slowly.

I'm told this could be when the throttle body get dirty the revs can drop

facade

patman99 wrote: »

If I remember correctley, the Ford Focus alternator is only one part of the charging system. The main part that monitors the voltage and ramps up/down output from the alternator is built in to the dashboard and requires the whole dash to be replaced if faulty.


Might be worth paying out for a full diagnostics check first before spending out on a new alternator and finding the fault is still present.

Apparently the wires get damaged and cause this problem


http://www.valeoservice.com/data/master/webfile/2945759434DDE6E8714173.pdf

Norman_Castle

consumers_revenge wrote: »

I'm told this could be when the throttle body get dirty the revs can drop

I'll assume the answer is yes.
https://www.youtube.com/watch?v=qt4VysW5NWc

System

The alternator drive belt should be changed at 10 years/125.000 miles. Assuming that the drive belt isn't slipping the alternator is shagged. It can't maintain the charge voltage under load. At no time under any condition other than when cranking the engine should a system register below 12.7V whether thats sat there with no keys in the ignition or sat there with everything turned on and the engine running. With the engine running even on idle it should be registering 14.4V.