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    Re: Charging System Questions? Archived Message

    Posted by Tony Sefton on August 15, 2009, 10:47 pm, in reply to "Re: Charging System Questions?"

    >>>>>>>>>>>>Sorry it this is too heavy for a Friday night. :? <<<<<<<<<


    YES.



    Who in their right mind would want to start a car up, with the heater plugs on, and turn on the HRW, Heated front and rear Screen, heater blower, etc and leave it ticking over. ??

    Tell them to use some common sense and not turn everything on and not to leave the car ticking over with all the loads on. And don't buy diesels to do short journeys.


    ( Educate the customer into how to use the vehicle properly rather than trying to work around why hes using it badly. )

    most older vehicles will not charge enough on tick over to cover all the loads on the vehicle.

    The above results also depend on the condition and state of charge of the battery in the first place. So its pointless checking that the alternator will cope with all the load if the battery is flat in the first place. ( i,e if theres a battery drain or the customer left the interior light on all night. )

    I would not normally condemn an alternator for not covering loads on tickover.

    i always start the car. put it on fast idle and then gradually turn on the loads and make sure that the alternator can cope at that speed. if it can't. i then check for volt drop on the cables before condemning the alternator and also check the D + voltage ( if it has a D+ Terminal. ) And also make sure that the battery is in a decent state of charge before checking as the alternator cannot usually cope with charging a flat battery and cover the loads as well. ( I have had some really poor charging results on vehicles after replacing the alternator as the battery is such a low state of charge, and it is surprising how long it has to be left on charge before you get a good result )




    P.S. I don't use an ammeter or scope. just a voltmeter is Usually enough to tell you if the alternator can cope with the job. if the alternator cannot provide the current, then the voltage will drop showing up the problem.


    Fast idle. 13.8 - 14.5v ish no load
    Fast idle. above 13.4v full load. ( preferably as much as possible. 14v on modern cars. )

    P.S. Yes i have been to the pub so if all this is twoddle, i will correct it tomorrow.

    H.T.H. Tony.

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