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Weak alternator
Topic Started: Sep 2 2015, 02:38 PM (681 Views)
MPG


How many volts should my alternator be testing Showing 12.4 volts
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Metromightymouse
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Powdercoat Wizard

14 some odd
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MPG


Metromightymouse
Sep 2 2015, 02:48 PM
14 some odd
Hmm That explains the battery dying out 😕. Thankx MMM 😀 Guess I'll get it rebuilt
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Memphis metro


How are you measuring alternator output? Normal charging rate is 13.9-14.1
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myredvert
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myredvert

FSM Section 6D3 Charging System
 
With all accessories turned off, connect a (voltmeter) across the battery. Run the engine at a moderate speed and check the voltage.

Some considerations should be given to the temperature to which the generator is exposed during this test. As the temperature of the regulator case in the generator increases, the voltage
output will decrease (Figure 1).

The standard setting for the voltage regulator is 14.2 - 14.8 volts at 25°C (77°F).
The upper end decreases linearly with an increase in temperature, and with the temperature in the high 80s, close to 90 like it has been near you the last few days a hair over 14.0V for a minimum would be appropriate.
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MPG


Memphis metro
Sep 2 2015, 04:19 PM
How are you measuring alternator output? Normal charging rate is 13.9-14.1
Tester clamped on alternator lugs with engine at an idle
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Old Man


Try reving to about 1000 RPM. My lights etc go dim at an idle because the alternator is not at its efficiency at that low RPM. Just as soon as I get a little above idle the lights go brighter indicating that the alternator is more efficient at a little higher RPM

EDIT; If that gives you better voltage then go to your battery for the same test. If it is considerably lower at the battery then start cleaning wire connections/grounds/replacing wires.
Edited by Old Man, Sep 12 2015, 11:06 AM.
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myredvert
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myredvert

The Factory Service Manual test in in post #5. Voltmeter connected to the battery.

The FSM doesn't specify what "moderate rpm" is, but I would follow Old Man's advice and use a minimum of 1000 if not more.
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MPG


:hmm Will try your suggestions Thankx Old man & redvert
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