Alternator wiring question

[dart_68]

Hello all.

I've got a Denso Toyota alternator that's rated at 100 amps (might be 90). I've done a little research and I should be running 4 gauge battery cable to a 100 amp fuse then to the battery.
Is this right? I somehow doubt the factory ran a 4 gauge wire. If it doesn't need to be 4 gauge..what gauge should I use?

Thanks in advance!

 

[67Dart273]

What length, and is this a "one wire?" (One wire units require larger wire because the one and only wire is also the sense wire)

According to this chart, (and charts vary)

Automotive Wire Size Calculator – Wire Gauge Chart | MGI SpeedWare

Find the right automotive wire size using an interactive AWG chart that takes into account load current, temperature, wire length and voltage drop.

mgispeedware.com

5ft of wire could be no8 and 7ft should be no6

If this is NOT a "one wire" the charge wire can be smaller and suffer more voltage drop, because the regulator (if the sense is run to the battery) will just ramp up the charge voltage to keep battery at proper charge level, and the charge wire will have a little more drop

Also if you do not have a great deal of accessories, water pump, big fuel pump, huge stereo, etc, etc, you will not normally be using "much" of that 100A capacity

Also if you do not have access to large wire, you can parallel no10 wire. It is nominally good for 30A, so 3x in parallel is good for 90A