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I recently completed an upgrade of my original 1987 Catalina Motorola 55 AMP internally regulated alternator with the C34 project Electrical Upgrade recommendation of a Blue Circle 100 AMP alternator (perfect fit rebuilt alternator) and a new Balmar 3 stage external regulator. After many checks and heavy expectation of a wiring issue, the wiring appears to be correct. I have also connected the AO directly to the battery bank with a #2 wire. I have checked the voltages of the regulator and the alternator with expected outputs. Twice now, though, the alternator has overheated (quickly way too hot to touch), started to burn, and fried the diodes (perhaps not in that order). This occurred once with partially depleted batteries (4 T105s in series-parallel) and once after fully charged. After the local alternator shop replaced the diodes the first time, I completed some more further testing after the alternator was re-installed while connected to shore power and charging the batteries at various RPMs. Everything seemed to work correctly, no burn smell, and the expected voltage output. As soon as I left the dock and kicked up some RPMs, I could smell the alternator burning and then noticed the voltage drop to battery voltage.

I believe the new external regulator is working and the alternator seemed okay at first and then fixed, checked again to be working correctly. I certainly think that if I get the alternator fixed again, the same situation will occur. The only thing that "I think" occurs differently from when it has worked until it fails is:

1) connected to shore power and charging the batteries (this may or may not have been the case during the first failure)
2) slightly longer run time at higher RPMs (after leaving the dock)

I was heading out on a one week vacation on the boat, so I ran the engine with the key off after starting the engine to cut out the alternator output. I kept my batteries charged with a Honda geni and shore power while away. While continuing to diagnosis the issue, I fairly quickly slightly smell the burning from the alternator if I leave the key on after starting the engine. As expected, there is no charging voltage coming from the alternator.

Any thoughts on what might be causing this? I am at a loss unless there is actually a failure of the alternator or regulator which I do not think is likely the issue. The marina yard mechanics are also at a loss, but their skills (or patience to resolve an issue) are sometimes questionable.

Thanks to the many wonderful posts on the C34 website, I think I am ready to tackle many much needed electrical upgrades on my 1987 C34. These include upgrading to 4 6V T105s, a high output externally regulated alternator, dedicated starting battery with echo charger, 1800W charger/inverter, and a battery monitor. I have procured the main components and am now zeroing in on wire, connectors, and fuses. I will be completing these upgrades in phases but in order to ensure I have the overall right approach, I have created a wiring diagram of the planned upgrades.

I have based much of my plans on the previously posted electrical upgrade details by Jim, Stu, and others. I am indebted to their generosity in sharing their information, approach, diagrams, and pictures! A few of the changes that I have made are the inclusion of a charger/inverter which (as I have read many posts about) requires very large 2/0 wire over a short distance AND a desire to keep the switch disconnects as simple as possible. I have read the many discussions about the different ways to utilize switches including the existing stock Perkins switch. I would like the primary "source" power (DC from batteries or AC from shore power) to be wired to switches on the existing Catalina AC/DC panels. I am going to replace the DC battery selector with a new Blue Sea e-series switch with has 3 positions for Off, On, and Combine (Emergency). Specifically, I want to wire all DC loads including the inverter and starting battery echo charger on this same switch. I would rather not have parallel or sub switches even though I do forgo some flexibility. I would also like to use some pre-purchased 1/0 wire and connectors for the battery interconnects but am not sure if this would be recommended with the 2/0 wire required for the inverter as a later part of the upgrades.

I have attached the document I created of my schematic. Please ignore some of my naivety in the diagram symbols. I think I pretty much used (or labeled) things correctly, but I am sure any electrical engineers would notice a few that are not correct ;-). Any help, guidance, or other thoughts would be appreciated. I think I understand the general concepts, but the devil is in the details. It will be frustrating enough to pull the 2/0 and 1/0 wire. I do not want to also set my boat on fire because of a unintentional oversight in the design.

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