what is the maximum allowed alternator voltage?

Discussion in 'The Projects Forum' started by pothineniuk, Dec 20, 2009.

  1. pothineniuk

    pothineniuk Thread Starter New Member

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    Hi,

    Today I took my Ford focus car to garrage for servicing and MOT. The guy told me that the alternator needs to be replaced as it is producing 14.9 volts power. Do we have any upper limit for the voltage?
    Could anyone suggest me if it really needs to be changed? as it costs more than £150?

    Thanks for the help.

    Babu
  2. eng1ne

    eng1ne Member

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  3. SgtWookie

    SgtWookie Expert

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    14.9v is quite high. I would check the battery voltage after the car has been sitting with the engine off for at least 4 hours. It should measure about 12.7v to 12.9v when fully charged.

    £150 sounds about the going rate for an alternator replaced by a mechanic.

    However, if you are handy with tools, it is not very difficult to replace the regulator module in the alternator. It is much less expensive if you do it yourself; I'd guess you could fix it for about £10 if you already have the tools. However, I have no idea how mechanically inclined you might be.
  4. THE_RB

    THE_RB AAC Fanatic!

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    A lot of the newer alternators especially on smaller cheaper cars have the regulator integral to the alternator. It's not always replaceable. Sometimes riveted in, some are even molded into the endcap of the alternator.
  5. pothineniuk

    pothineniuk Thread Starter New Member

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    Thanks for the useful advise.

  6. CarlM123456

    CarlM123456 New Member

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  7. SgtWookie

    SgtWookie Expert

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    Here is a thread on another forum directly related to alternator problems in the Ford Focus:
    http://autoforums.carjunky.com/Auto...on_03_Ford_Focus-_Everything_Replaced_P34404/

    It appears from statements made in the thread that the alternator output is controlled by "a computer", not a regulator internal to the alternator. What computer this might be was not explained.

    I don't know; I've never worked on a Ford Focus.
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