Well, I replaced the positive battery cable, the starter relay, the voltage regulator, the ballast resistor, the battery and I also did this little trick;
Wiring Upgrade
I have performed the following upgrade on my own charging system with good results. I chose to perform the upgrade this way because 1) it was easy and 2) it does not require cutting, modifying or otherwise tampering with existing electrical wires. As said earlier, the original electrical system design was higly ineffecient. Electricity leaving the alternator was sent all throughout the cabin of the car before ever reaching the battery to charge it. Here we will add a single charging circuit, comprised of 2 heavy gauge wires, that will route alternator juice right into the battery, effectively shunting the existing wiring. Go back to the wiring diagram and trace the original circuit path from the alternator (R6-12-BK), through 'P' on the bulkhead, into the dash mess, back out through 'J' (S4-16-BR) on the bulkhead, to the starter relay (battery). The new wiring circuit goes from the alternator, to the starter relay (battery), minus the mess in the middle. Electricity favors the path of least resistance and the big fat heavy gauge wire will now carry the bulk of the current which originally would have gone through the smaller gauge mess that came from the factory.
The ammeter will, as a result, be rendered useless. In it's place I wired up a neat little digital voltmeter. With the unit inside the car mounted on my dash, I ran the wires for the voltmeter into the engine compartment connected directly to the battery, giving me a no-bullshit assessment of whether my battery is being charged or not. One nice thing about the digital voltmeter is that it is backlit and has idiot lights that blink and beep if the voltage drops below 11volts.
Start by disconnecting the battery (red positive lead comes off) thereby shutting off electrical power to the car. Unless you enjoy sudden, unexpected jolts of electricity.
Run a length of red 8 gauge from the BATT post of the alternator with a fusible link crimped on the end and secure it to the BATT post of the starter relay. Proper sizing of the fusible link is two gauge sizes smaller than the wire it is meant to protect (ie. an 8 gauge charge wire will need 12 gauge fusible link) and about 3 inches in length. NAPA sells fusible link by the roll. Make sure you have a fusible link on the end of this wire that gets secured to the starter relay; do not install this charge wire without a fusible link. Run a second length of red 8 gauge from the positive terminal on the battery, again with fusible link at the end, to the starter relay.
An extra step that wouldn't hurt: Trace the wire that runs from the alternator BATT terminal, through the bulkhead connector, to the negative side of the of ammeter behind the dash; note where it is. Then trace the wire that runs from the starter relay BATT post, through the bulkhead connector, to the positive side of the ammeter. Disconnect the wire from the negative side ammeter connection and secure it over the positive one. This disconnects the ammeter from the electrical system all together.
That's pretty much it. Make a few extra lengths of fusible link to carry as spares.
What your voltmeter will tell you :
10.0v - 12.9v = Under charging...!
13.0v - 15.0v = Normal charging
16.0v +plus = Overcharging..!
