Testing alternators
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    Default Testing alternators

    Gurus- I have a couple of alternators I decide to try to test. Rigged up an electric motor with fan belt to alternator on a bench. Connected cables to a battery B+ to Pos and ground from the alternator to -. Flicked the switch and checked on the multimeter for charging volts. Battery was already at 12.9 before testing and showed the same. swapped voltage regulators (both Bosch with same reg). No change. I'm looking for something like 14.4 V from alternator. Am I missing something? Or are both voltage regulators cactus?
    Cheers
    Lou

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    1000+ Posts robmac's Avatar
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    Are the alternators internally regulated or do they have external regulators ?

    What is make and model of them ?

    To test an alternator you need, if externally regulated wire up the regulator, if internally regulated supply power to the internal regulator.

    Also be aware that full output is dependent on the driving speed.

    What is the RPM of the alternator shaft under test ?

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    Regulators are internal and interchangeable- both standard Bosch. I could not see any connection to power up the regulator. Thought it may receive power from inside (unless a D+ or D- have something to do with it, I am not an electrician).
    240V motor RPM is 1440, the pulley is larger than the alternator on so that would be around the 2300-2600 RPM.

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    Hi Loudel
    You know Bosch probably made 1000+ alternator types over the years ! So perhaps a few more details might help. Quite probably the two regulators are toast. Why were the alternators taken off a car. Are the brushes OK.
    Some earlier models needed a connection to an charge light to kick off the charging. Later models did not.
    Look here on google and see if yours look like any of the pictures.
    https://www.google.com/search?q=bosc...hrome&ie=UTF-8
    Jaahn
    Last edited by jaahn; 25th July 2019 at 10:11 PM.
    Hotrodelectric likes this.

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    Gentlemen thankyou for your input.
    All I can deduce from the alternators is the regulator Bosch ee14V3 9190067009 - both the same. One alternator is an Ingram, the other a Bosch. They were removed from a scrapped DS and a CX, the CX one almost certainly playing up. I swapped the regulators. Could be that both regulators are toast. I'll try with a wire to a light from the D+ and batt neg next week when I am home again.
    Cheers
    Lou

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    Quote Originally Posted by Loudel View Post
    Gurus- I have a couple of alternators I decide to try to test. Rigged up an electric motor with fan belt to alternator on a bench. Connected cables to a battery B+ to Pos and ground from the alternator to -. Flicked the switch and checked on the multimeter for charging volts. Battery was already at 12.9 before testing and showed the same. swapped voltage regulators (both Bosch with same reg). No change. I'm looking for something like 14.4 V from alternator. Am I missing something? Or are both voltage regulators cactus?exc
    Cheers
    Lou
    Unless you connect a 3w globe to the warning light circuit, the diodes won't excite, therefore no charge, , also be aware an LED will not do the job
    cheers Pete

    I am gunna get another 403 on the road........one day

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    Thanks Pete, time eludes me for now, though upon my return home I can rig up a 12v globe then give it a go. Will report in due course.
    Off to the "7000 Islands" this morning.
    Cheers
    Lou

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    Ideally you should have some method of loading the alternator.

    A bank of headlight globes or high power resistors is the usual method.

    Most test rigs also have a voltmeter and ammeter.

    You do need to check the machine under test can deliver it's fully rated current.

  9. #9
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    If the alternators are from CX's .... Yes I would suggest they are certainly "toast". The regulators sit right next to the exhaust manifold and get fried. I'm sure its mentioned above, but don't forget to hook up and idiot light, it is functional.. they require an exciter.
    'Cit' homepage:
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    '78 GS1220 pallas
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    Yay ... No Slugomatics


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    D+ means Dynamo Plus. Ignition on supply to that. This turns the Rotor ( spinning electromagnetic Field) on and off electrically. This no turned on, mean No Electrickery owt!
    D- is the earth wire connection back to chassis ground or such.

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    Not being electrickery minded- I gave up. I did manage to get the exciter light on from 1 alternator, but not the other so I scrapped that one. The seemingly 'good' one I gave to a friend who knows a retired auto electrician to verify.
    I did learn something through your contributions for which I thank you.
    RegarDS
    Lou
    And, Shane, yes that CX one was most likely cooked from being so close to the exhaust.

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