Electrical

I have had my RV7a for 3 years now. initially thought I had a bad alternator (diagnosed by A&P). Replaced but still continued to show Low Voltage at EIS (13.2-13.5) and 10-11.3 going to the EFIS. We then chased down an rectifier diode that seemed to also be going bad and causing GRT displays to power down when transmitting. fast forward about a year and Seems Rectifier diode is again going bad. Alternator is charging 14v at the batter but EIS and EFIS are back to 13 and 10-11v. It would be easy just to replace the diode but I would like to used this for (simple) IFR in the future. Any thoughts. Otherwise I have had almost no issues with the plane beyond normal wear and tear. Hate the thought of even thinking of selling it.

I'm not an expert in this area, but I do know that rectifier diodes require heatsinking if you are pushing a lot of amps through them. Is it possible that excess heat is causing premature failure?

Are you able to test at both sides of the diode to ensure that the diode is the source of the voltage drop? Do you have any electrical architecture documentation from the builder? I'm wondering if maybe some components/wiring are undersized for the actual loads.