About the 'Big 3' upgrade....

[Jexx]

I think the Big 3 upgrade is excellent, where once a HO alt has been put into a car, the corresponding wires are upgraded to handle the new amperage.

But....I wanted to know about why two of the wires are upgraded....

Why would the alt to battery (+) be necessary? Wouldn't it be better to just hook the amp (+) right up to the alt post? In other words, is there an electrical advantage, or is it just out of practicality (hooking up a bunch of wires to the alt (+) post would be cumbersome).

What is the significance of upgrading the chassis to battery (-) wire? Is this necessary?

In a way...why is the car's electrical hooked up to the battery posts and not directly to the alternator?

The chassis to engine wire makes perfect sense on the other hand.

Thanks!

[infinia]

Connections are made at the battery because in a way it acts like a big capacitor to stabilize the voltage and alt noise and provides a reservoir of peak current capacity. The alternator voltage regulator current is a function of RPM, so the battery is providing the accessory current most times anyway.

[Jexx]

Thanks so much for the response!

[jol50]

Some upgrade the alt to battery positive, I don't see the point with a stock alternator or they must have wired the car wrong. With a HO alt it may help due to the increased amperage it can generate. Upgrading the body to battery ground is a good idea, even though that wire is typically really short and does not need to be as large, but since the amps are usually grounded to the body this wire makes the circuit back to the battery for them. Upgrading the battery negative to engine or alternator is usually also pointless with a stock alternator maybe even HO alt. The engine starter is grounded with a larger cable that should handle near any amount of current.

Note the above may not be true for huge multiple Kw spl systems and high output alternators. Really one should ***** every wire in light of the alternator and demands on the system since it depends on what current and distance you have there. It can all be calculated. I see a lot of people put huge wire in they don't need, on the other hand if you want it big for looks none of this matters much.

Think of the battery this way....if you have a water well with a pump at your house, and a pressure tank to hold the water, you don't hook your faucet to the pump you hook it to the tank. If you put it on the pump the pressure would go high and low when the pump was on and off. Technically it would not matter as much with larger piping, but you can still get vibration from the pump up your pipes. Many well pumps had a rubber hose section pump to tank for this reason. The tank and hose serve to cushion the pressure change and vibration of the water just like the battery does for electricity.