Alternator lead wire hot
07-31-2014, 07:59 AM
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Alternator lead wire hot
Lead wire from alternator is too hot to touch. Have new alt. and new battery.ran 2 new wires from fusible link direct to alternator to bypass the harnessjust to be sure its not in the harness. wire still got hot to touch.Ran a #6 wire from alternator main lead direct to battery. no wires got hot but now alternator is too hot to touch. Anyone have any ideas
07-31-2014, 10:06 AM
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Lead wire from alternator is too hot to touch. Have new alt. and new battery.ran 2 new wires from fusible link direct to alternator to bypass the harnessjust to be sure its not in the harness. wire still got hot to touch.Ran a #6 wire from alternator main lead direct to battery. no wires got hot but now alternator is too hot to touch. Anyone have any ideas
It sounds like there is a serious drain after the fuseable link.
What is the battery voltage when the engine is running? Has that changed since installing the new Alt & battery?
07-31-2014, 10:24 AM
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It may very well have been. I'm not sure, I was doing some wiring and covered all the wires with loom. i noticed the loom melted and it brought this issue to my attention.Voltage is 13.5 engine running 14.5 at alternator terminal.
08-01-2014, 11:19 PM
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In basic terms, if the entire length of wire is becoming too hot, then it has too many amps going through it for its size. However, if the high temps are localized - like toward one end - then you might want to check the terminals and be sure there is not excessive resistance caused by corrosion or a bad crimp. Loose wire crimps can become very hot indeed, sometimes even melting the plastic connectors themselves. As a matter of policy, I solder all connectors and splices – but other competent folks do not – it’s all about preference.
You have a one volt drop between the alternator and wherever you were checking the voltage at - 14.5 dropping to 13.5 - that is a bit high which equates to high resistance someplace in that specific circuit. The maximum voltage drop I like to see is 0.1-volt for each connector and another 0.1-volt for each switch. This is with a heavy load but not necessarily a full rated load. When circuits are running at full rated load, they will get a little warm so the 0.1 volt drop is not always applicable. If the resistance at full rated load is too high, resulting in higher than acceptable voltage drops, the engineer will specify a larger wire to compensate for these increases in temps and resistance.
I do not know what the maximum alternator output is for our platform but it is probably somewhere around 100 amps – others smarter than I can chime in with the exact number. However, if you are running an upgraded “super duty whammy whatever” high output alternator it is very probable that your wire from the alternator output terminal to the battery or to its junction point will now be undersize - this will result in higher temps than was experienced with the stock alternator.
Time to check the amount of amps that are flowing – voltage is important but so is determining current flow.
Any chance the output terminal on the alternator is loose – little wiggly and not secure?
Good luck and get back to us as to what you found.
Jake -
You have a one volt drop between the alternator and wherever you were checking the voltage at - 14.5 dropping to 13.5 - that is a bit high which equates to high resistance someplace in that specific circuit. The maximum voltage drop I like to see is 0.1-volt for each connector and another 0.1-volt for each switch. This is with a heavy load but not necessarily a full rated load. When circuits are running at full rated load, they will get a little warm so the 0.1 volt drop is not always applicable. If the resistance at full rated load is too high, resulting in higher than acceptable voltage drops, the engineer will specify a larger wire to compensate for these increases in temps and resistance.
I do not know what the maximum alternator output is for our platform but it is probably somewhere around 100 amps – others smarter than I can chime in with the exact number. However, if you are running an upgraded “super duty whammy whatever” high output alternator it is very probable that your wire from the alternator output terminal to the battery or to its junction point will now be undersize - this will result in higher temps than was experienced with the stock alternator.
Time to check the amount of amps that are flowing – voltage is important but so is determining current flow.
Any chance the output terminal on the alternator is loose – little wiggly and not secure?
Good luck and get back to us as to what you found.
Jake -
08-06-2014, 02:24 PM
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In basic terms, if the entire length of wire is becoming too hot, then it has too many amps going through it for its size. However, if the high temps are localized - like toward one end - then you might want to check the terminals and be sure there is not excessive resistance caused by corrosion or a bad crimp. Loose wire crimps can become very hot indeed, sometimes even melting the plastic connectors themselves. As a matter of policy, I solder all connectors and splices – but other competent folks do not – it’s all about preference.
You have a one volt drop between the alternator and wherever you were checking the voltage at - 14.5 dropping to 13.5 - that is a bit high which equates to high resistance someplace in that specific circuit. The maximum voltage drop I like to see is 0.1-volt for each connector and another 0.1-volt for each switch. This is with a heavy load but not necessarily a full rated load. When circuits are running at full rated load, they will get a little warm so the 0.1 volt drop is not always applicable. If the resistance at full rated load is too high, resulting in higher than acceptable voltage drops, the engineer will specify a larger wire to compensate for these increases in temps and resistance.
I do not know what the maximum alternator output is for our platform but it is probably somewhere around 100 amps – others smarter than I can chime in with the exact number. However, if you are running an upgraded “super duty whammy whatever” high output alternator it is very probable that your wire from the alternator output terminal to the battery or to its junction point will now be undersize - this will result in higher temps than was experienced with the stock alternator.
Time to check the amount of amps that are flowing – voltage is important but so is determining current flow.
Any chance the output terminal on the alternator is loose – little wiggly and not secure?
Good luck and get back to us as to what you found.
Jake -
You have a one volt drop between the alternator and wherever you were checking the voltage at - 14.5 dropping to 13.5 - that is a bit high which equates to high resistance someplace in that specific circuit. The maximum voltage drop I like to see is 0.1-volt for each connector and another 0.1-volt for each switch. This is with a heavy load but not necessarily a full rated load. When circuits are running at full rated load, they will get a little warm so the 0.1 volt drop is not always applicable. If the resistance at full rated load is too high, resulting in higher than acceptable voltage drops, the engineer will specify a larger wire to compensate for these increases in temps and resistance.
I do not know what the maximum alternator output is for our platform but it is probably somewhere around 100 amps – others smarter than I can chime in with the exact number. However, if you are running an upgraded “super duty whammy whatever” high output alternator it is very probable that your wire from the alternator output terminal to the battery or to its junction point will now be undersize - this will result in higher temps than was experienced with the stock alternator.
Time to check the amount of amps that are flowing – voltage is important but so is determining current flow.
Any chance the output terminal on the alternator is loose – little wiggly and not secure?
Good luck and get back to us as to what you found.
Jake -
08-06-2014, 07:05 PM
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Ahh - don’t think cooling fans are your problem area. The alternator should keep up with the cooling fans with no trouble - even if they have almost (or completely) seized armatures in which case their fuse will open due to current overload.
If the alternator output lead is getting hot along its entire length then the alternator is putting out too many amps for the wire to handle - there is no other cause. Since the current output of an alternator is self-limiting at a given voltage, the most logical answer is the alternator voltage is excessive but since you checked it and found it to be at 14.5 volts, this is not the case here. Are you absolutely sure the alternator output voltage is 14.7 – as measured between the alternator output terminal and the negative battery post?
Anyway, the alternator output wire is too small for the current you are asking it to carry. Most likely causes are; the alternator has been upgraded to a larger unit or the alternator voltage is excessive. High alternator voltage will allow it to produce too many amps and cause the alternator to run hot - too hot will result in premature failure (burning) of your alternator – like really quickly too.
If the alternator output lead is getting hot along its entire length then the alternator is putting out too many amps for the wire to handle - there is no other cause. Since the current output of an alternator is self-limiting at a given voltage, the most logical answer is the alternator voltage is excessive but since you checked it and found it to be at 14.5 volts, this is not the case here. Are you absolutely sure the alternator output voltage is 14.7 – as measured between the alternator output terminal and the negative battery post?
Anyway, the alternator output wire is too small for the current you are asking it to carry. Most likely causes are; the alternator has been upgraded to a larger unit or the alternator voltage is excessive. High alternator voltage will allow it to produce too many amps and cause the alternator to run hot - too hot will result in premature failure (burning) of your alternator – like really quickly too.
08-06-2014, 10:16 PM
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Ahh - don’t think cooling fans are your problem area. The alternator should keep up with the cooling fans with no trouble - even if they have almost (or completely) seized armatures in which case their fuse will open due to current overload.
If the alternator output lead is getting hot along its entire length then the alternator is putting out too many amps for the wire to handle - there is no other cause. Since the current output of an alternator is self-limiting at a given voltage, the most logical answer is the alternator voltage is excessive but since you checked it and found it to be at 14.5 volts, this is not the case here. Are you absolutely sure the alternator output voltage is 14.7 – as measured between the alternator output terminal and the negative battery post?
Anyway, the alternator output wire is too small for the current you are asking it to carry. Most likely causes are; the alternator has been upgraded to a larger unit or the alternator voltage is excessive. High alternator voltage will allow it to produce too many amps and cause the alternator to run hot - too hot will result in premature failure (burning) of your alternator – like really quickly too.
If the alternator output lead is getting hot along its entire length then the alternator is putting out too many amps for the wire to handle - there is no other cause. Since the current output of an alternator is self-limiting at a given voltage, the most logical answer is the alternator voltage is excessive but since you checked it and found it to be at 14.5 volts, this is not the case here. Are you absolutely sure the alternator output voltage is 14.7 – as measured between the alternator output terminal and the negative battery post?
Anyway, the alternator output wire is too small for the current you are asking it to carry. Most likely causes are; the alternator has been upgraded to a larger unit or the alternator voltage is excessive. High alternator voltage will allow it to produce too many amps and cause the alternator to run hot - too hot will result in premature failure (burning) of your alternator – like really quickly too.
08-06-2014, 11:53 PM
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OK, thanks for the update - looks like you've got a handle on the problem. Seems the cooling fans are putting just enough extra load on the system to cause the high temps near the fuse links. Similar things might happen with other heavy draws like headlamps or rear winddow defogger too.
Fusible links can cause some weird issues as they age. Think you are correct in replacing them but make sure to use the ones with the correct amperage rating. Fusible links are there for a purpose - to protect the wiring and other electrical components downstream.
#12 fusible link wire is not going to handle the alternator output - it will get warm - even hot- and it will open up - blow/melt from too much current. Use the correct size fusible link wire. Decades ago, they used to be color coded - dunno if they still are or not.
Might want to check other things out before replacing them with higher amperage pieces too- - because well, just hate to see you smoke some things downstream - that can get expensive, like having your car burn to the ground.
The alternator doesn't "absorb" any amps nor does it create any amps, it just pushed the electrons (current) along. Every amp which leaves the alternator at the output wire immediately "re-enters" the alternator back through the ground side (frame) of the system.
Good luck -
Jake -
Fusible links can cause some weird issues as they age. Think you are correct in replacing them but make sure to use the ones with the correct amperage rating. Fusible links are there for a purpose - to protect the wiring and other electrical components downstream.
#12 fusible link wire is not going to handle the alternator output - it will get warm - even hot- and it will open up - blow/melt from too much current. Use the correct size fusible link wire. Decades ago, they used to be color coded - dunno if they still are or not.
Might want to check other things out before replacing them with higher amperage pieces too- - because well, just hate to see you smoke some things downstream - that can get expensive, like having your car burn to the ground.
The alternator doesn't "absorb" any amps nor does it create any amps, it just pushed the electrons (current) along. Every amp which leaves the alternator at the output wire immediately "re-enters" the alternator back through the ground side (frame) of the system.
Good luck -
Jake -
Last edited by jake corvette; 08-07-2014 at 04:19 PM. Reason: added info
08-07-2014, 09:12 AM
#9
Burning Brakes
I thought the stock main charging wire coming off the alternator was 8awg. 10 gauge would be too small to handle the 105 amps that the alternator's capable of. I had this problem, and it turned out that the crimp on the end at the alternator had gone bad. But, my wire wasn't hot the whole length - more localized to that end, although the wire does conduct heat farther from the bad terminal.