A few comments on the electrical loading and 12 Volt vs 24 Volt choices, and my experience with ordering versus getting the proper alternator and the infamous coupling. 

Like most builders, I did a Power analysis and concluded I needed the 100 Amp alternator to have a safely designed system. The big mistake I made was not asking more about the 12 Volt Vs 24 Volt question.  Indeed, I am sorry I did not, as if I was allowed to change only one thing on the project, it would be to use a 24 Volt system.  The reasons are many, and I am not an electical engineer, but let me simply advise all builders who can still make that decision to seriously consider going 24 volts.

I bought my TSIO-550 direct from Lancair, and ORDERED a 100 Amp 12 Volt Alternator.  Reality is that I GOT a 70 Amp Electrosys (now called Prestolite) Alternator which is the ALX model and ALX is indeed rated at 70 Amps.  No question is was supposed to be 100 Amps, but when checked out by the auto-electric shop, it could only put out 70 Amps.  I have been advised that for 100 Amps, I need the ALS (Is there a 100 Amp model available from Continental??) model on the engine. 

This research all came about due to intermittant low voltage problems we had with our electrical system, and as most readers of this list know, the real problem was the coupler (or Hub as some call it) that Continental  first wanted $1500 for. They finally gave me part free under warranty, but only after my engineer raised hell, and it still cost a lot to have the engine lifted so we could remove the oil pan and sure enough, we found a big piece of the reddish rubber that had broken off the coupler, and which could have been really bad news to the oil circulation if it blocked an important channel for oil (or so I was told) by my engine man who I trust a lot more than I do the people from TCM. 

I have spoken to other builders and am amazed these problems are common. You planned for and ordered 100 Amp Alternator but got 70 instead, and with the defective hub, low voltage problems occur, and when under full load, pushing to full amperage (for us it is when the hydraulic pump kicks in) is major load on the system.  My conclusion is that an extra significant source of electrical power is a good thing.  We are hopeful the Northcoast Deice system becomes a reality, as we will install in a minute, because then we will have an extra alternator driven by a belt and that is a good thing for redundancy, safety, and peace of mind when flying IFR high and fast, plus dealing with icing which up here is Canada is not theoretical anytime of the year.

Gerry Leinweber C-GLFP IV-P