MOD A modern electrical power design for the Carbon Cub EX-3/FX-3

[ve6yeq]

With all the recent discussions about how the default electrical power configuration for EX-3/FX-3 with "IFR" panels is not living up to expectations, I am thinking through a design modernization that takes advantage of recent building blocks. I am posting my current design concept here to see if anyone has any comments on what I have missed or can improve on.

My long-term goal is to use my 2024 Carbon Cub EX-3 to explore Northern Canada, Greenland, and Iceland. This will require some long legs with >2h from the nearest possible diversion location, which will require both additional fuel (belly fuel pod and/or ferry tank) and upgrades to the electrical system.

My current research has led me to a design concept that uses a single critical systems backup battery (EarthX EBBS), a dual generator (from Monkworx), and an "accessory" deep-cycle battery (e.g., a "powerbank").

This design concept is inspired by RVs, and Mike Patey's "Scrappy" with an "accessory" battery to both take advantage of deep-cycle, high-capacity batteries and enable use of Starlink, USB-C device charging, etc., when not in flight, without draining the main CCA-optimized starter battery. The dual generators (2 x 30 Amps) will provide redundancy and extra power for future updates, such as Starlink, XeVision LED lighting, etc. The unified "critical systems" bus is powered by an EarthX EBBS or IBBS 6 Ah to provide backup power for precautionary landings without the complexity and maintenance (e.g. short lifetime of AGM battery) of the existing IBBS and manual AGM ignition backup.

The overall system is not that different from the default Carbon Cub EX-3 w/ "IFR" panel wiring harness, so I hope it will be more of a reconfiguration than a complete replacement of the current wiring harness.

 

[Cactus Charlie]

Some random, and possibly conflicting, thoughts as I wake up.

Considering your mission I think I'd like to see COM and IFR approach capability on the critical bus. They can always be shed if not needed.

I don't see the GAD 29 which must be present to convert GNC ARINC buses to CAN.

I don't think G5 needs to be on Critical bus. Its backup battery should last longer than any other battery in the system and it's another bit of wiring that could take critical bus down.

I like to see isolation between the two generators. perhaps one feeds critical bus and the other main bus. One generator should be able to supply useful power if the other has its output shorted.

With the problems I have seen with GSU 25 I'd like to have two and at least one of them should be the new -55 version.