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  #31  
Old 10-12-2017, 02:09 PM
rv7charlie rv7charlie is online now
 
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Ding!

While I wouldn't say that it's EarthX's responsibility to manage over voltage, we users do need to understand all the implications of any new tech, part of which means understanding what the new tech will do in abnormal situations.

Explanations so far don't seem to line up with conventional electrical theory.
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  #32  
Old 10-12-2017, 02:21 PM
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Carl Froehlich Carl Froehlich is offline
 
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Quote:
Originally Posted by bret View Post
Or... instead of the word blocked at a particular voltage, is the battery going to open circuit internally to protect the cells and by that action allowing the full unrestrained runaway voltage from the alternator to go straight to the main bus and burn everything up?
I've read all the literature on this battery and while EarthX goes to great lengths to mitigate potential risks, this specific design feature bothers me.

In short, the battery does a nice job of protecting itself. In doing so it removes itself from the main buss and no longer presents a load to the runaway alternator - so buss voltage goes where it might. In a legacy battery install the pilot would have at least a few minutes as the battery absorb the excess current before it failed. These few minutes might be enough for the pilot to recognize the over voltage condition and take action.

Nothing is perfect and a crowbar over voltage protection is required, not just desired on our aircraft. On the one alternator over voltage condition I experienced the crowbar did not trip at 15vdc - but I was able to get on the ground before it got much above that. I just wonder if EarthX would consider an approach that allowed the battery to die in exchange for a few more minutes before the panel fries. Perhaps such an option presents the risk of battery catastrophic failure - I don't know.

Carl
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  #33  
Old 10-12-2017, 02:36 PM
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Originally Posted by EarthX Lithium View Post
In the event of a charging system failure where the voltage increases to above 15.5V, the resistance to charging current increases, and above 16V the charging current is completely blocked. The time delay for this feature is 1 second to allow the aircraft alternator’s over voltage protection (crowbar circuit) to activate first. This design offers charge voltage protection greater than 40V. The discharge current (current out of battery) is unaffected in this situation. EarthX requires having automatic over-voltage protection (crowbar) for alternator type charging systems (not required for <20 Amp pad mount standby alternators).”
This was one of the biggest problems I had seen with the EarthX, and it appears they've got it solved, at least partially - in the case of electric-dependent aircraft or IFR/IMC conditions requiring electrical power, an alternator failure could take your entire system down unless the battery stays online to supply current after the alternator has been taken offline, either manually or automatic via crowbar. My aircraft is electrically dependent for both fuel and nav, so I have a fully redundant electrical system - but I decided against the EarthX because of the original (perhaps erroneous) information presented that the battery would go open-circuit on alternator failure and go completely offline. Even now, with this explained, the battery still has the possibility of going open-circuit if it falls below a certain threshold voltage. My PC680 will at least give it's life more gradually and give partial power for longer without just finally throwing up it's hands and saying "That's it, I quit." I can't take the chance of the battery going open-circuit during discharge, I demand that the battery continue discharging all the way to its death without either bursting into flame or going open-circuit suddenly - therefor I'm running lead-acid. For a VFR aircraft the lithium technology may be just the greatest thing ever - but for electrically-dependent applications it cannot be counted on for deep discharge.
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Last edited by airguy : 10-12-2017 at 02:39 PM.
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  #34  
Old 10-12-2017, 05:29 PM
vic syracuse vic syracuse is offline
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Greg, I ran some tests on my RV-10 which are posted on this site and in a KP article. Basically, the Earthx battery supplies enough juice to crank an IO-540 twice for 20 seconds, then run a full up flight load of avionics and everything else for 45 minutes, and then still cranked the IO-540 twice more for 20 seconds. And it cranked it faster after 45 minutes than the Odyssey did fresh, and had lots more voltage available at the end of that test than did the Odyssey.

I can't imagine not being able to get on the ground within an hour if I had an electrical problem. Perhaps the EarthX and the Oddysey might probably time out at the same time, with the Oddysey just going completely dead and the Earthx taking itself offline. Quite honestly, from what I have seen I bet the Earthx would end up lasting longer.

Vic
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  #35  
Old 10-13-2017, 07:44 AM
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Quote:
Originally Posted by vic syracuse View Post
Greg, I ran some tests on my RV-10 which are posted on this site and in a KP article. Basically, the Earthx battery supplies enough juice to crank an IO-540 twice for 20 seconds, then run a full up flight load of avionics and everything else for 45 minutes, and then still cranked the IO-540 twice more for 20 seconds. And it cranked it faster after 45 minutes than the Odyssey did fresh, and had lots more voltage available at the end of that test than did the Odyssey.

I can't imagine not being able to get on the ground within an hour if I had an electrical problem. Perhaps the EarthX and the Oddysey might probably time out at the same time, with the Oddysey just going completely dead and the Earthx taking itself offline. Quite honestly, from what I have seen I bet the Earthx would end up lasting longer.

Vic
Which EarthX model were you testing, and how in the world did I miss that report?
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  #36  
Old 10-13-2017, 09:57 AM
444TX 444TX is online now
 
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Here we go again.

I have been tempted to open a new thread with a discussion concerning the great risks builders are taking with their lack of failure resistant design. The verbal beatings that would have followed have kept me quiet.

I had voiced my concerns on a previous overvoltage thread and it got immediately shut down. Soon after I received a private message (below) from Earth X with seemingly little knowledge of the serious repercussions of poor charging system design. I only responded once, feeling further communication was a waste of time.

Adding all these EXPRIMENTAL items to our aircraft can add great risks. Some here are fully aware of these (known and possibly unknown) risks, take great care to test their new ideas, and to our benefit keep us informed of what they have done. They make it look easy. We do not see the thoughtful planning and implementation of their ideas, plus the flight tests planned and performed to always leave an out. Others just jump in with unconscious incompetence planning to fly IFR.

It is past the time to have a serious discussion on more than Lithium battery and alternator choices. Some one is going to get hurt. Or worse.

George Meketa



-----------------Earth X (received private message)------------------------------

I see the thread on overvoltage has been closed so I thought I would send you a quick note about your comment "did the alternator problem start the OV or the did the battery cause the over voltage issue."

It was neither. The regulator is what failed . A battery is not able to create voltage, this is not only scientifically impossible but against the laws of physics at this time. A battery, lead acid or lithium are recipients of voltage, not the producers.

-----------------MY RESPONCE (private message)---------------------------------

Originally Posted by 444TX
Here is the problem. People do not understand how a charging system works. There is more than one failure mode with similar results.

A battery that goes open circuit can cause an overvoltage event. The alternator having no overvoltage protection or a way to be shut down will allow the event to continue. Having a battery that has circuitry, as the primary battery, that can go open from high or low voltage events should be at least questioned for use in aircraft. I just recently replaced my main battery, before this thread, and used another pc680.

Like I stated. There are so many failures that occurred in this thread, with many comments showing a lack of understanding to how dangerous things were, that I felt a comment was warranted. When things are dangerous I will speak up.

So was it the battery or the alternator?

George

----------------(EARTH X, second private message)-------------------------------

Dear George,
Sorry for the delay in response. Safety is our main concern as well, so we can appreciate when you see something that strikes you as dangerous you speak up. That is what a forum such as Vans is all about in addition to helpful suggestions about building, maintaining an RV, etc.
In the experimental market, you can build your aircraft as you desire. When you mention that if you have an “alternator having no overvoltage protection or a way to be shut down”, this is indeed a very unsafe, dangerous and unwise configuration no matter what. I do not know of a single scenario of an aircraft that does not have the ability to switch off the alternator because of this and not sure if you could get an airworthiness certificate without it.
An alternator creates voltage, a battery receives it. A battery can not create voltage, this is impossible. All charging systems have a regulator as that is what “regulates” the alternator and keeps the voltage in an acceptable range to operate the aircraft. If the regulator fails, then you should have the overvoltage protection on the regulator that would automatically disconnect from the alternator. In reference to the thread about the overvoltage situation, the regulator failed which caused the voltages to go very high and damage the electrical equipment. The EarthX brand of batteries have over voltage protection for the battery for protection which was engaged and worked. Without it, not only would the plane had electrical damage, but he would have had battery damage too. It was not the battery. It was not the alternator. It was the failed regulator that did not have overvoltage protection that caused the overvoltage situation.
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  #37  
Old 10-13-2017, 10:32 AM
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scrollF4 scrollF4 is offline
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George,
It looks to me that you and EarthX are in agreement. Both of you seem to be saying the charging system must have overvoltage protection to open the circuit and protect the ship's systems (not just the battery) if the voltage spikes dangerously. This is accomplished through an internal or external voltage regulator with overvoltage protection (crowbar) or a specific overvoltage protective function in Vertical Power-Pro VPX. EarthX is saying that we builders absolutely need this protection...that it needs to be a non-negotiable requirement in our systems' design.

In that, you two seem to agree (as do many others in this thread), and that's a good thing.
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  #38  
Old 10-13-2017, 11:04 AM
vic syracuse vic syracuse is offline
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Quote:
Originally Posted by airguy View Post
Which EarthX model were you testing, and how in the world did I miss that report?

Here you go:

http://www.vansairforce.com/communit...=Earthx&page=7
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  #39  
Old 10-13-2017, 12:01 PM
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Vic, if you click on the post #, and copy it into your post like this... http://www.vansairforce.com/communit...1&postcount=69
you are then sent direct.
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  #40  
Old 10-13-2017, 12:10 PM
vic syracuse vic syracuse is offline
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Quote:
Originally Posted by gasman View Post
Vic, if you click on the post #, and copy it into your post like this... http://www.vansairforce.com/communit...1&postcount=69
you are then sent direct.
Thanks. That's better. I was so happy to just be able to find it.

Vic
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