21 May 2024, 13:20 [ UTC - 5; DST ]
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Post subject: Re: You say you want an Evolution ... Posted: 27 Apr 2024, 12:05 |
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Joined: 12/10/07 Posts: 31148 Post Likes: +11020 Location: Minneapolis, MN (KFCM)
Aircraft: 1970 Baron B55
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Username Protected wrote: Or you could let the VRs work exactly the way they always have, put a standard BMS on the batteries as I described above, and stick a capacitor on the bus to absorb transients. That’s the simplest solution to me. 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.
_________________ -lance
It's easier to fool people than to convince them that they have been fooled.
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Post subject: Re: You say you want an Evolution ... Posted: 05 May 2024, 22:44 |
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Joined: 11/22/12 Posts: 2625 Post Likes: +2395 Company: Retired Location: Lynnwood, WA (KPAE)
Aircraft: 1993 Bonanza A36TN
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Username Protected wrote: Dave, what was the incompatible behavior of the TB batteries? 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.
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Post subject: Re: You say you want an Evolution ... Posted: 05 May 2024, 23:06 |
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Joined: 07/06/14 Posts: 3070 Post Likes: +2026 Location: MA
Aircraft: Cessna 340A
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Username Protected wrote: Dave, what was the incompatible behavior of the TB batteries? 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. It's hard to believe they would be so ignorant. A 50ms dropout is indeed a spec in some standards (it's in MIL-STD-704, not sure about DO-160), but designing to run through that is to protect through a fault, not an acceptable behavior for a power source. (Not doubting your story, but it calls into question their competence / judgment.)
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Post subject: Re: You say you want an Evolution ... Posted: 06 May 2024, 10:18 |
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Joined: 12/10/07 Posts: 31148 Post Likes: +11020 Location: Minneapolis, MN (KFCM)
Aircraft: 1970 Baron B55
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Username Protected wrote: It's hard to believe they would be so ignorant. A 50ms dropout is indeed a spec in some standards (it's in MIL-STD-704, not sure about DO-160), but designing to run through that is to protect through a fault, not an acceptable behavior for a power source. (Not doubting your story, but it calls into question their competence / judgment.) 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.
_________________ -lance
It's easier to fool people than to convince them that they have been fooled.
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Post subject: Re: You say you want an Evolution ... Posted: 06 May 2024, 18:06 |
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Joined: 08/24/13 Posts: 8555 Post Likes: +3776 Company: Aviation Tools / CCX Location: KSMQ New Jersey
Aircraft: TBM700C2
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Username Protected wrote: Dave, what was the incompatible behavior of the TB batteries? 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.
That's not good
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Post subject: Re: You say you want an Evolution ... Posted: 06 May 2024, 20:50 |
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Joined: 11/08/12 Posts: 6402 Post Likes: +3910 Location: San Carlos, CA - KHWD
Aircraft: Piaggio Avanti
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Username Protected wrote: 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. 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?
_________________ -Jon C.
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Post subject: Re: You say you want an Evolution ... Posted: 07 May 2024, 00:12 |
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Joined: 11/22/12 Posts: 2625 Post Likes: +2395 Company: Retired Location: Lynnwood, WA (KPAE)
Aircraft: 1993 Bonanza A36TN
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Username Protected wrote: 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.
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Post subject: Re: You say you want an Evolution ... Posted: 07 May 2024, 00:18 |
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Joined: 11/08/12 Posts: 6402 Post Likes: +3910 Location: San Carlos, CA - KHWD
Aircraft: Piaggio Avanti
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Username Protected wrote: 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. Wow, good to know. Thanks for letting us know.
edit: Uh… just looked it up, and that is a marine battery… ?? Wonder if their aviation batteries do anything different. Would be good to ask.
_________________ -Jon C.
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Post subject: Re: You say you want an Evolution ... Posted: 09 May 2024, 09:07 |
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Joined: 11/08/12 Posts: 6402 Post Likes: +3910 Location: San Carlos, CA - KHWD
Aircraft: Piaggio Avanti
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Username Protected wrote: 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.
_________________ -Jon C.
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