That does sound simple but without doing the math I'd guess you'd need a pretty large capacitor to absorb the transients that a battery can.

Transient voltage drop out, then back, all within 35 msecs. Some kind of periodic BMS self-test, I believe we were told. The story we (finally) got was that they'd been told avionics couldn't see anything shorter than 50 msecs, which they took to mean that as long as they kept it shorter than that they could do anything they wanted, without documenting it. They may be right about most avionics, but those transients were flagged by our touch screen, which uses hardware from the world of Formula 1 auto racing, causing it to throw a fault and reboot. Not documenting it is bad enough, but repeatedly denying it even after we found it and showed them the data cost us MONTHS of wasted effort.

Transient voltage drop out, then back, all within 35 msecs. Some kind of periodic BMS self-test, I believe we were told. The story we (finally) got was that they'd been told avionics couldn't see anything shorter than 50 msecs, which they took to mean that as long as they kept it shorter than that they could do anything they wanted, without documenting it. They may be right about most avionics, but those transients were flagged by our touch screen, which uses hardware from the world of Formula 1 auto racing, causing it to throw a fault and reboot. Not documenting it is bad enough, but repeatedly denying it even after we found it and showed them the data cost us MONTHS of wasted effort.

What strikes me as even more obnoxious behavior is that their engineers clearly adopted the idea that it was OK to deliberately cause an anomaly that anyone using the spec on the load side would expect to be anything but deliberate.

Transient voltage drop out, then back, all within 35 msecs. Some kind of periodic BMS self-test, I believe we were told. The story we (finally) got was that they'd been told avionics couldn't see anything shorter than 50 msecs, which they took to mean that as long as they kept it shorter than that they could do anything they wanted, without documenting it. They may be right about most avionics, but those transients were flagged by our touch screen, which uses hardware from the world of Formula 1 auto racing, causing it to throw a fault and reboot. Not documenting it is bad enough, but repeatedly denying it even after we found it and showed them the data cost us MONTHS of wasted effort.

Can you share which model battery? Do you know whether they planned to correct it (software update maybe)? Or do the TB batteries all still do this?

It was the TX16. And since they didn't document or admit the behavior on this model, there's no way to know if they do the same on their other models. But I expect they'd use common BMS logic across their entire model line, so it's likely the same for all of them.

It was the TX16. And since they didn't document or admit the behavior on this model, there's no way to know if they do the same on their other models. But I expect they'd use common BMS logic across their entire model line, so it's likely the same for all of them.

OK, you guys made me dig through my records.

We first installed TB's TX16, the one that other Evos had used successfully. After we encountered the conflict and traced it back to the batteries, we swapped them out for TB17-2 batteries. They're TSO'd, and considerably more expensive, but exhibited the same behavior. Which buttresses the suspicion that it is common through their model range.

Yes, I agree it is probably common to all of them then.

Sometimes a little change can make a big difference. A recent update to the G3X Touch let it know flap position and adjust the AoA indication, which made the AoA far more useful for being on-speed on final. With the high-aspect ratio wing and effective flaps, once it's in ground-effect the Evo is reluctant to lose energy. A few knots too fast and it will float like a Mooney. But with the more accurate AoA, my personal minimum runway length has dropped from 3,000 to 2,000 feet. Then I fly home at 300 KTAS. Amazing machine.

Fantastic. I always wondered if the Garmin AOA would end up being dynamic with flap inputs.

Is the Evo prone to a prop strike setting it down at slightly higher ref speeds? Something a la TBM.

The trailing link planes I've flown are great with mains that droop far below a straight legged plane. Let's you fly the plane on a little sooner even if you're carrying a little extra speed.

My personal conclusion is that a TBM at higher ref speeds is subject to PIO when it bounces at a higher speed. As long as you know the right reaction to a bounce then you aren't going to get a prop strike.

This is where trailing link gear helps as it reduces the bounce.

Good question, so I called and asked Aaron. He said no, our prop clearance is more than that of a TBM or even an Epic (he happened to be testing an Epic when I called). Neither of us could recall any Evo prop strikes from landing too fast or PIO, they've been instead from taxiing into/over things, like snowbanks and taxiway lights.

Most Evos don't have AoA, and I do think most are landed too fast. An informal survey at last year's fly-in found even high-time owners mostly had personal minimum runway lengths of 3,000 to 3,500 feet. But apparently it hasn't led to prop strikes.

But that would mean dropping the bus voltage below the nominal 28v while the batteries were charging. This would likely be better than causing the batteries to disconnect but I don't think it's a very good solution and it would involve a much more significant change to the aircraft's electrical system than just altering the battery type. That said, IIRC the Earth X requires the voltage regulators to be adjusted to something higher than 28v in order to charge the batteries. So maybe it would only be necessary to drop the voltage down to 28v in order to prevent excess charging current.

But it seems to me that Earth-X could/should incorporate charge limiting in their BMS in a way that doesn't require disconnecting completely. Then again, to provide the full benefit of a battery on the bus the charge limiter would need to maintain a fairly low impedance to the bus and that's somewhat opposite of the normal concept of charge limiting but I know it can done in a way that's effective for short duration transients.