| Infamous Nichrome Alternator Wire [message #365955] |
Sat, 07 August 2021 19:19  |
Greg C.
Messages: 224
Registered: October 2019
Location: Knoxville, TN
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I am deep into my new dash project. I have spent the last couple of days neatening up the factory wiring harness at the fire wall, cutting some of the old connectors, and crimping on new connectors for the new switches and gauges.
I've been reading several posts from Bruce Hislop about the nichrome wire/resistance wire. I actually PM'd him, but he did not respond. While my wiring harness is totally accessible, I would like to address the nichrome wire issue. Bruce had written at some point about installing a 10 ohm 25 watt power resistor in series with a non-resistor type wire to replace the nichrome wire.
His posts enlightened me quite a bit about this subject. I now understand that the GEN light receives power from both wires going to it, unless one wire is carrying less voltage than the other, which causes the light to light either dimly or brightly, dependent upon the voltage difference between the two wires. This would indicate either battery or alternator voltage dropping below normal levels.
One thing I am not clear on is the exact purpose of the resistance wire. Is it to protect the GEN light bulb from burnout if there is no/low voltage on one wire?
He had also posted that the APC cable may not prevent the resistance wire from overheat, thus the 10 ohm resistor in lieu of the APC cable.
Bruce also posted that his coach was wired so that the resistance wire is connected to the RUN circuit of the switch, and not the ACCY circuit, which seems to be the factory norm. It is conceivable that leaving the switch in the ACCY position for some time could cause the wire to overheat. I understand the concept, but don't know exactly where to tap into the RUN circuits for the resistance wire connection.
So my questions are: do I understand this correctly? What IS the best way to approach this problem?
And if I change the resistance wire to the RUN circuit, where is the best place to cut/splice/tap?
Thank you for your time.
Greg Crawford
KM4ZCR
Knoxville, TN
"Ruby Sue"
1977 Royale
Rear Bath
403 Engine
American Eagle Wheels
Early Version Alex Sirum Quad bags
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