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03-30-2019, 05:07 PM
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Join Date: Aug 2017
Location: Sebastopol,CA
Posts: 358
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Quote:
Originally Posted by rv7charlie
Where are the essential avionics; are there duplicates on each bus? If the avionics are on the 'aux avionics' switch....
Oh, edit: Fail the 'milspec' master switch. What happens?
edit2: From the drawing and accompanying text, it looks like start current will be on your main bus (?).
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Remember, this is a schematic not an installation drawing. In the actual installation, the two main contactors will be co-located with their output sides joined, along with a heavy cable going from there to the nearby starter solenoid. So Yes, the starter, as per normal, will be on the main bus, which extends all the way down to the contactor outputlugs.
The mil-spec master is a 20Amp high qualiy switch that will never be asked to carry more than the one amp required to activate the contactor coils on one pole and the even tinier milliamp load of the mini-solenoids on the other pole. Not a likely point of failure, but completely unrelated to operation of the engine.
As for the avionics power pathways, they are pretty well explained. The Aux avionics switch provides a means by which a selection of avionics can be operated even if some problem forces the shutdown of the main bus, making it pretty much a non-event.
__________________
Otis Holt-
RV-7A (bought)
Built Monnett Moni
Frmr Test Pilot/Author CAFE APR's:
RV-8A, S-7C, Europa, Glastar.
-2019 VAF donation!!-
"RV-Fun is inversely proportional to RV-Weight!"
Last edited by Hartstoc : 03-30-2019 at 06:51 PM.
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03-30-2019, 05:26 PM
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Join Date: Aug 2017
Location: Sebastopol,CA
Posts: 358
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Quote:
Originally Posted by bret
My backup battery is simple and no relays, just the 30A rated switch to tie into the three seprate fuse block busses, pump 1, ECM 1, Coil 1 on one fuse block, pump 2, ECM 2 Coil 2 on the other fuse block, and the avionics are on the third fuse block buss if I need to load sheed to keep the engine running longer, hand held for BU com. the Dynons monitor both battery volts and only switch on the BU battery during run up and taxi to top off, then switch off. To test the back up battery, BU battery on, alt field off, master off. fan still turning? then master on, alt field on, BU battery off.

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Bret- Beautiful! My first thoughts on the topic were along these lines and I find no fault whatever with your solution.
Where I’ve ended up going with this approach is intended to be a departure from the norm that takes full advantage of these magical new batteries we have available now. Their power to weight ratio is so high that it opens new possibilities. All of the battery related mods I’m installing for the system I describe here together weigh no more than one PC680! Why have a backup battery at all when it is so easy to have a full blown, interchangeable, full twin battery system. If I ever have any operational issues with one of the EarthX batteries I can completely isolate it from the system with the flip of a few switches, and be left with a completely normal operational system with no compromise of any kind, and I never have to worry that my backup battery may be getting a bit old, may not be fully charged, has reduced capacity, etc. also, my starter is going to be delighted to have 800CCA available on call.
__________________
Otis Holt-
RV-7A (bought)
Built Monnett Moni
Frmr Test Pilot/Author CAFE APR's:
RV-8A, S-7C, Europa, Glastar.
-2019 VAF donation!!-
"RV-Fun is inversely proportional to RV-Weight!"
Last edited by Hartstoc : 03-30-2019 at 05:41 PM.
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03-30-2019, 05:40 PM
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Join Date: Aug 2017
Location: Sebastopol,CA
Posts: 358
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Quote:
Originally Posted by Walt
Totally disagree, an unplanned short to one of these 'hot busses' can have serious consequences (I've seen it happen).
If you don't think one wire can create enough smoke/heat to cause a fire maybe you should try it.
Nothing worse than an electrical short that you can't shut off, all you can do is watch it burn.
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Well, I appreciate your concern, but you would have to judge the installation rather than the schematic. If something direct-shorts anywhere along the cable connecting your battery post to your contactor input lug, you are in the same exact pickle you describe above. I’ll be working with much shorter hot runs than the one you probably have on your bird right now. The option to add another disconnect, of course, exists here, but you would also be adding a potential failure point. (EDIT 3/31–Walt- after thinking more about this, I did see an easy way to provide circuit protection on the ELB feeds, abd it also gives me more flexibility in battery location, so I’ve added it and will notate the schematic. Thanks for your input!- Otis)
__________________
Otis Holt-
RV-7A (bought)
Built Monnett Moni
Frmr Test Pilot/Author CAFE APR's:
RV-8A, S-7C, Europa, Glastar.
-2019 VAF donation!!-
"RV-Fun is inversely proportional to RV-Weight!"
Last edited by Hartstoc : 03-31-2019 at 08:05 AM.
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03-30-2019, 06:29 PM
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Join Date: Aug 2017
Location: Sebastopol,CA
Posts: 358
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Quote:
Originally Posted by Brantel
What about the BMS system in each of the EarthX batteries?
It has electronics and some sort of micro controller built into it. Guess what, that requires firmware/software and you guessed it, both batteries will be the same.
There are eight fault light errors listed in the manual. Some of them require up to thirty minutes of monitoring to determine meaning.
There are at least two abnormal conditions where the BMS will disconnect the battery from the bus. Likely taking out both of them at the same time.
So far #1, #2, and #3 have not met your examples....
PS, this not a slam against EarthX. I will likely be using them in my RV-10 and would have one in my RV-7 if it were not for I need the weight where it is and I don?t want one mounted on the engine side of the firewall.
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Brantel- Thanks for your response. I distinguish between software/firmware and circuitry with hard-wired discrete logic, which I believe better describes the EarthX BMS, but of course you would have to ask EarthX about that directly. I do not believe that there is even a mechanism for ?firmware? upgrades(anybody who knows more please weigh in!) I see no reason why a simultaneous shutdown would occur since the two in my system are completely isolated from one another except during the very brief occasions when I activate the momentary switch, and I do not believe the BMS is a hair-trigger device.
I did talk to Reg and Kathy at EarthX about the momentary interconnect feature in my design. Reg told me there should be no concern if the two are within a few volts of one another. That is the reason I added the two V/A meters, and SOP will be to observe voltage on both prior to engaging the momentary. -Otis
__________________
Otis Holt-
RV-7A (bought)
Built Monnett Moni
Frmr Test Pilot/Author CAFE APR's:
RV-8A, S-7C, Europa, Glastar.
-2019 VAF donation!!-
"RV-Fun is inversely proportional to RV-Weight!"
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03-30-2019, 06:49 PM
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Join Date: Aug 2017
Location: Sebastopol,CA
Posts: 358
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Quote:
Originally Posted by lr172
I also found it interesting that the entire redundancy system is driven by a single point of failure. Though maybe the backup is to hold down the momentary switch. You do realize that every bump in turbulence may result in an on off power cycle to the entire bus. Kinda rough on the avionics.
Larry
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Sorry Larry, I don?t get it. I?ve been flying for 39 years, mostly in airplanes with whimpy rocker-masters, and I?ve never once had one flip off due to turbulance. A mil-spec toggle holds position very stiffly, and given that this one is a DT mounted horizontally, less likey to be knocked out of position by turbulance than those mounted vertically. Also, don?t forget that Aux. Avionics switch on the ELB powering input #2 to nearly all of my avionics. They would not even notice it if you turned off the master on purpose.
Also, you hold the momentary up, not down.- Otis
__________________
Otis Holt-
RV-7A (bought)
Built Monnett Moni
Frmr Test Pilot/Author CAFE APR's:
RV-8A, S-7C, Europa, Glastar.
-2019 VAF donation!!-
"RV-Fun is inversely proportional to RV-Weight!"
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03-30-2019, 08:13 PM
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Join Date: Mar 2006
Location: Newport, TN
Posts: 7,496
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Quote:
Originally Posted by Hartstoc
Brantel- Thanks for your response. I distinguish between software/firmware and circuitry with hard-wired discrete logic, which I believe better describes the EarthX BMS, but of course you would have to ask EarthX about that directly. I do not believe that there is even a mechanism for ?firmware? upgrades(anybody who knows more please weigh in!) I see no reason why a simultaneous shutdown would occur since the two in my system are completely isolated from one another except during the very brief occasions when I activate the momentary switch, and I do not believe the BMS is a hair-trigger device.
I did talk to Reg and Kathy at EarthX about the momentary interconnect feature in my design. Reg told me there should be no concern if the two are within a few volts of one another. That is the reason I added the two V/A meters, and SOP will be to observe voltage on both prior to engaging the momentary. -Otis
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Take a look at the pictures of the BMS, it is a far cry from hard wired discrete logic with passive electronics. Just because EarthX does not make firmware upgrades available to the end user does not mean it does not have any.....
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03-31-2019, 08:01 AM
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Join Date: Aug 2017
Location: Sebastopol,CA
Posts: 358
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Quote:
Originally Posted by Brantel
Take a look at the pictures of the BMS, it is a far cry from hard wired discrete logic with passive electronics. Just because EarthX does not make firmware upgrades available to the end user does not mean it does not have any.....
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I will take a look- really though my concern with software/firmware has more to do with ?upgrades? that can introduce unexpected behavior triggered by some unanticipated set of conditions. Far less concerned about established, proven code. I?m not at all concerned about simultaneous battery shutdown in this installation.- Otis
__________________
Otis Holt-
RV-7A (bought)
Built Monnett Moni
Frmr Test Pilot/Author CAFE APR's:
RV-8A, S-7C, Europa, Glastar.
-2019 VAF donation!!-
"RV-Fun is inversely proportional to RV-Weight!"
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03-31-2019, 10:04 AM
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Join Date: Mar 2006
Location: Newport, TN
Posts: 7,496
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Quote:
Originally Posted by Hartstoc
I will take a look- really though my concern with software/firmware has more to do with ?upgrades? that can introduce unexpected behavior triggered by some unanticipated set of conditions. Far less concerned about established, proven code. I?m not at all concerned about simultaneous battery shutdown in this installation.- Otis
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History has shown it is so called proven code that takes out most systems in this failure mode.
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03-31-2019, 11:49 AM
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Join Date: Aug 2017
Location: Sebastopol,CA
Posts: 358
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Quote:
Originally Posted by Brantel
History has shown it is so called proven code that takes out most systems in this failure mode.
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In my experience as a home-automation technician, it has generally been firmware and software updates that lead to grief, with end-users left playing the role of guinea pigs left to discover the glitches.
I hope that the good folks at EarthX will weigh in here on the much-maligned BMS, which has to be pretty **** simple software-wise. The BMS is there to protect the battery and the user, and the EXT900-VNT’s I’m installing are on the verge of FAA certification for use in production aircraft. It is the ONLY battery available DESIGNED for safe installation in the passenger cabin and it features a closed containment vessle and overboarding vents for noxious gasses. I’ve been bench-testing the two going into my plane for some time, and I am blown away by thier performance.
Some people, perhaps you included, are going to remain sceptical about these new technologies for some time, but I have not heard anything here that will disuade me from making this installation. Don’t forget, I’ll have two of them and they will be colsely monitored. The indicator outputs will be wired into my G3X Touch and cofigured to get my atention at the slightest anomoly. If ANYTHING of concern pops up, I can instantly and completely isolate the offending battery from my working system, yet be left with a fully operational, no-compromise electrical system with huge stored power reserves. All this in a complete system that weighs about the same as one properly mounted PC680! What’s not to like about that?
That said, I truely appreciate every effort to blow holes in my design strategy. My fear was that someone would point out some fatal flaw in my design that would save my butt but make me feel like an idiot. Happily, nothing like that so far, but please keep it coming!- Otis
__________________
Otis Holt-
RV-7A (bought)
Built Monnett Moni
Frmr Test Pilot/Author CAFE APR's:
RV-8A, S-7C, Europa, Glastar.
-2019 VAF donation!!-
"RV-Fun is inversely proportional to RV-Weight!"
Last edited by Hartstoc : 03-31-2019 at 11:52 AM.
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03-31-2019, 01:22 PM
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Join Date: Mar 2006
Location: Newport, TN
Posts: 7,496
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Quote:
Originally Posted by Hartstoc
In my experience as a home-automation technician, it has generally been firmware and software updates that lead to grief, with end-users left playing the role of guinea pigs left to discover the glitches.
I hope that the good folks at EarthX will weigh in here on the much-maligned BMS, which has to be pretty **** simple software-wise. The BMS is there to protect the battery and the user, and the EXT900-VNT’s I’m installing are on the verge of FAA certification for use in production aircraft. It is the ONLY battery available DESIGNED for safe installation in the passenger cabin and it features a closed containment vessle and overboarding vents for noxious gasses. I’ve been bench-testing the two going into my plane for some time, and I am blown away by thier performance.
Some people, perhaps you included, are going to remain sceptical about these new technologies for some time, but I have not heard anything here that will disuade me from making this installation. Don’t forget, I’ll have two of them and they will be colsely monitored. The indicator outputs will be wired into my G3X Touch and cofigured to get my atention at the slightest anomoly. If ANYTHING of concern pops up, I can instantly and completely isolate the offending battery from my working system, yet be left with a fully operational, no-compromise electrical system with huge stored power reserves. All this in a complete system that weighs about the same as one properly mounted PC680! What’s not to like about that?
That said, I truely appreciate every effort to blow holes in my design strategy. My fear was that someone would point out some fatal flaw in my design that would save my butt but make me feel like an idiot. Happily, nothing like that so far, but please keep it coming!- Otis
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I wish you the best of luck in your endeavor. I find it strange that you are so eager to dismiss simple proven technology/concepts and so willing to bet the farm on a smoke filled black box (not literally, just an analogy) that you have no real knowledge of internally. Your mind appears to have been made up long ago and the true motive behind these post appears to be something different than stated.
As I said before, this has nothing to do with EarthX and their BMS, I would use them in a heartbeat. It is about how they break your criteria you specified earlier. Seems to be very double standardish in nature.
But hey, this is experimental aviation. Go for whatever you like and want to do!
Last edited by Brantel : 03-31-2019 at 01:40 PM.
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