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| Every once in awhile voltage is low upon startup briefly. https://slantsix.org/forum/viewtopic.php?t=56526 |
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| Author: | Sam Powell [ Mon Nov 10, 2014 4:19 am ] |
| Post subject: | Every once in awhile voltage is low upon startup briefly. |
Every once in awhile the volt meter reads ten volts upon initial start up, and the lights are dim. When I rev the engine a few times the voltage suddenly jumps to 12.5 and the lights brighten up. This alternator is a one wire, GM unit. Any ideas about what is going on? Is this something in the alternator itself, or an external connection maybe? Dash also has aftermarket volt meter in dash. The dim lights verify the low voltage, so trust the gauge. Sam |
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| Author: | nm9stheham [ Mon Nov 10, 2014 7:26 am ] |
| Post subject: | |
Some regulators take some level of current or voltage in certain places as a signal to start regulating or change their regulation process. The old Ford systems used stator current flow as a signal for the regulator to kick into full operation. I expect that your alternator simply needs a certain RPM to activate the regulator; otherwise the regulator would have to be on at all times (since there is no way to disconnect the regulator from the battery like in a multiwire alternator configuration) and would drain the battery while the car is sitting. It depends on some residual magentism in the field and/or some small leakage through the regulator to make the alternator put out a bit of juice at start-up, and that will signal the regulator that the alternator is spinning and it is time to fully activate. (BTW, you can see this residual field magentism even in Mopar alterantors; with a dead VR, they usually will still put out a very weak charging voltage when spinning fast enough.) |
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| Author: | Pierre [ Mon Nov 10, 2014 10:08 am ] |
| Post subject: | |
Yep, minimum rpm needed for one wires to kick in. May vary by temperature, wouldn't surprise me to see this condition more in cold weather. |
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| Author: | Sam Powell [ Mon Nov 10, 2014 1:28 pm ] |
| Post subject: | |
Thanks guys. It is good to know it works according to plan. Sam |
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