I see that some people are saying that #10 wire is way too small. I'm curious how that is being calculated. Local electrical
code where I live allows 50 amps of house current through plain old #10 THHN. Higher currents are allowed through #10 with high temperature insulation.
I'll have to go over to my office to look up voltage drops over long distances in order to get official numbers to work with, but off the top of my head
, I'm pretty sure that a 10 foot run doesn't rate a requirement for oversizing the conductor in any of the books
that I have. Also since this is the alternator wire, is the voltage regulator
not able to compensate for any small voltage drop that may occur over the length of that wire? Is a small voltage drop a big problem because this is only a 12v system? I'm not trying to disagree. I'm trying to understand the reason why #10 is a problem.
As I see it, at worst, #10 might be very slightly undersized if the temperature rating of the wire is low & in that case, #8 might be technically required. I mean, this is just the alternator wire that will never carry more than 55 amps, right? This isn't a wire that is going to carry full load battery amperage to a starting motor
, right? Starting motors can draw hundreds of amps. They need bigger wires. The alternator? A big wire there too? Really? Am I missing something?
Also, I seem to remember that old automotive manuals
said that you should not fuse the charging wire off of the alternator, but rather run it straight to the battery. I seem to remember that if that connection were broken for any reason, it would instantly fry the voltage regulator
on the alternator. Maybe that was then & this is now. Maybe modern voltage regulators are now immune to that problem. I don't know. I think that I would check on that possibility before making a change though.
Diodes will always give you a noticeable voltage drop. I can't remember for sure off the top of my head
what the actual number is, but I think it's like 0.7vdc per series connection. The number doesn't get bigger with increased current loading, like resistive voltage drops do.