High amp alternator

[DaveK]

Adding the extra ground cable (or oversizing the power cable and the ground cable) is just that much more assurance that you will not end up like that H2 in AB....

Amen to that.

[gon2srf]

You need to replace the negative cable when using a high output alternator for a very simple reason: electricity flows in a loop, and if one part of that loop has significantly less capacity or much greater resistance (usually one leads to the other) you risk overheating the weak link and causing damage to the alternator, cable, or in more severe cases, cause an electrical fire.

If you look at virtually any electrical device on the vehicle (or house, or plane, or boat), both the power and ground wire are of equal size; in some cases, such as high power 2-way radio equipment, both the negative and positive sides of the power cable are fused, as well.

Just because the original alternator is grounded to the engine by it's case, doesn't mean that it has sufficient ground for a higher capacity alternator that replaces it. You need to check the engine grounding straps or mounting points to see if there is a high enough capacity ground (usually not). Adding the extra ground cable (or oversizing the power cable and the ground cable) is just that much more assurance that you will not end up like that H2 in AB....

Great information Larry, thanks.