Was there ever a big market for this? Most serious single engine IFR airplanes with known Icing has two alternator already as mandated in the US. TB20/TB21 isn’t approved for known ice in the US, even with TKS because of this as it has only one alternator. I assume that why you have interest in this. All the twins inherently has two alternators, so there is no market there. Why socata didn’t opt for this in the first place is a bit weird since TKS was an option. Maybe because the extra drive off the back of the engine was not available at the time since a vacum system was needed in the times of mechanical gyros and to add another alternator in front of the engine is more expensive and complex. For VFR-only airplanes the need for a second power source is limited. Now most efis units (GI 275 fx) has built in battery that allows to find a place to land before the battery runs out. So I think it all comes down to a very limited market.
The main IFR SEP with two alts is the SR22. For sure it is the biggest seller in the last 20 years but it is far from the only IFR SEP flying and doing “serious IFR” trips around Europe. In fact I observe that SR22s don’t feature anywhere near pro-rata when one looks at who turns up at the more distant places; these are dominated by the older US types, but that is another discussion (already done IIRC).
And the problem with the “modern solution” – backup batteries in avionics – is that you get only a few hours before the screen goes blank, so the rest of the flight becomes pretty much an immediate emergency.
Probably not much of a market now, with the B&C product line (which uses the same Denso alternator actually) soaking up the most obvious STC-backed applications. But like with so many other things which had a time window of opportunity, GAMI could have done well with it.
I have a backup alternator already; done with a US Field Approval. I wrote it up here. Not trivial and beyond the tech/admin capability of a typical Europe based TB owner, so not really relevant.
All turbo Mooneys starting from the late eighties and all na starting from the mid nineties have dual alternators. IIRC the later Beeches as well, but I’m not sue about that.
terbang wrote:
All turbo Mooneys starting from the late eighties and all na starting from the mid nineties have dual alternators.
But apparently they share a voltage regulator, and when it malfunctions its a common point of failure. Based on a German friend’s experience when it malfunctions on the way to Oshkosh you end up flying to Peoria Illinois and spending several days looking at corn fields while the special voltage regulator is sent out for overhaul 
No, at least with ours there are two separate VRs, connected by a ‘sense‘ line to balance the output. However, the short body Mooneys with two alternators have only one battery (maybe the Bravos too, I’d have to check).
terbang wrote:
However, the short body Mooneys with two alternators have only one battery (maybe the Bravos too, I’d have to check).
The AOG charging system (regulator) failure I described occurred on a dual alternator Bravo.
I was surprised at the extent of the in flight electrical failure, stuff like the manifold pressure gauge quitting before he got it on the ground. Who would have thought the MP gauge on a ‘steam gauge’ panel would be electric? The fix was a new regulator plus one new alternator. The second alternator was OK.
Most late model 210’s have two alternators too, but a single battery.
There is an STC for B&C standby alternator on the earlier ones (that is what we have) , but that is not compatible with the dual vac pumps required for most deice boots installs.
No big deal since the majority of 210’s equipped with boots already have the dual alternators, and for the other ones there is a wind-turbine-driven back-up STC too.The B&C will not charge the battery fully (that requires 28+V and the B&C provides 26+) but it does keep most electrics powered for an unlimited time, allowing mostly seamless completion of your flight. The V delta is a requirement due to the activation system, which is not as smart as the supplenator was supposed to have been.
Installed a B&C two years ago, its a piece of mind at least the radios, xpdr, TKS, stby, horizon keep on running. With a GI275 you cant make a call to ATC :-)
I installed a B&C standby alternator on my 14V system in 2018 when I upgrade my panel to add a G500Txi/G5 with a GTN750 and removed the pressure pump. I have used it once on a flight and I was able to keep every essential system powered. The issue turned out to be a bad main CB from the alternator that took it off line. In one of its few failures, GAMI never completed certification of the Supplenator.
