[DrDave]

Greetings:

You only need to buy one regulator since the system only uses one regulator. The other regulator is a backup. This seems to be a point of common misunderstanding. Based on the wiring diagram for your airplane (mine too) it only uses one regulator for the system to operate. You said that the wiring to the alternator looks cracked. Check the picture below for comparison. This was removed from a 172 charging system.

I think we pretty well covered the basics of the field circuit. There's only three other areas of the charging system to address. I will be brief.

Now we need to deal with the alternator output leads. According to your diagram you have 30 amp breakers in the panel. The output wires appear to be 12ga according to the schematic. They used a shielded wire originally. The alternator output lead does not need to be shielded. That wire certainly needs to be updated. I'm guessing you have 30 or 35 amp alternators? That entire circuit needs to be rewired. Let's start with fresh 8ga wiring all the way from the alternators to the shunts. Look closely at the connectors at the shunts. Those can come loose and get hot and create all sorts of problems. Then run new #8's from the shunts to the circuit breakers. I like the Klixon 35 amp breakers. I believe the part number is 3TC2-35. These breakers are the most expensive component in the system at ~$165 each. 8ga. wire is rated for 40amps. That gives you plenty of load carrying capacity and low resistance. 8ga is still easy to work with. According to the diagram wire K-PA1 from the bus to the shunt is a 6ga wire. This is the wire that goes back to feed the battery. This wire also carries the load when the alternators are offline.

The only item left is the ground circuit for both the starter and alternator. I like running a piece of #8 from the base of the rear starter to the base of the front starter. This bonding provides a sold ground path for both starters and alternators. Run the new ground wire from the front motor to a common ground point for the front battery.

Send plenty of pictures of your current setup configuration. We will solve the charging problem with logical steps and system upgrades and repairs.

If you get all energetic and decide to do your entire circuit panel I have the templates for my panel that should fit yours. We could just have another back-plate cut. Oh yeah, when you pull out your circuit panel you will see the breakers are really close to the skin. I lined that entire area in polycarbonate. I made paper templates and took them to the plastic store to cut them out of thin scraps of polycarbonate. Total cost $7.

I've included two pictures of Cessna's idea of how to make a circuit panel...

Let me know if I can offer any clarification or assistance.

Dave