Hi

car been stood 6 weeks in garage.

started by jump leads. kept it running for approx 20mins and warmed up properly, fan kicked in and was idling fine.

turned off car, then failed to restart, no click, no noise, just dead as though trying to start car without battery.

called Greenflag, they said alternator is fooked, battery is fine. alternator should be giving 14 volts but was giving 12.55V , when increasing revs to 2500rpm, the reading did not fluctuate.

will it definatley be the alternator, car has only covered 45k miles, its a WRX 2005 Blobeye model.

car started again when Greenflag mechanic used his portable jump start machine.


any advise appreciated.

 

Disconnect battery and put on a slow trickle charge overnight,

Refit battery and re-test alternator,

Alternators can only charge to the potential of the battery,

Charging a flat battery using the alternator is like running a bath with the plug out

Just be aware of any alarm/radio code

 

The alternator on your model will not start charging until a load is drawn from the battery, so if the green flag technician was not aware it has a "smart charge" system, he would of tested it by raising the engine revs, and waiting for the alternator to receive a excite signal.
Try retesting the voltage with the engine running and turn your heater or lights on. It may be the battery has just gone flat with standing.

 

thanks, very good advice. i will do that. I have a voltmeter, so before starting the engine, I will first check the battery to see if it is giving 12.5 to 12.8 volts.
I will then jump start the vehicle with jump leads and the retest to see if the reading increases to 13.8 - 14.8 volts, I will also put load on alternator by switching on the lights and heater blower on full, if reading stays between 13.8v to 14.8v then alternator is good.
i will let you know what happened hopefully very soon.

 

I purchased a battery charger today from Argos, prior to putting battery on charge, I tested the battery with voltmeter and it read 7.83V, lets see if it reaches full charge after 12 hours.