Runaway overvoltage Need help!

[pvalovich]

I will second the much earlier suggestion that the folks at Aeroelectric Connection get involved.

http://www.matronics.com/digest/dige...e=AeroElectric

This is the kind of unique problem they thrive on.

[climberrn]

Originally Posted by airguy

...which still would not have helped in this situation, since the battery terminals themselves went cold due the BMS cutting them off.

Even if the battery went back online, most of my panel is Non-Op. Was going to put in a redundant electric backup for IFR in the future (G5, D10), but this instance really got me thinking. The only electronics that worked were iPhones with ForeFlight. Not my idea if a proper backup, but better than nothing.

[RV Jerry]

Years ago when Plane Power and B&C were not as popular I used automotive alternators with internal regulators and when the field was energized the alternator could not be shut down so I used a constant current relay in the B line then activateded it with the field switch I also installed a crowbar over voltage to the relay . The field wire was jupered at the alternator. So when field switch was turned off the alternator was completely out of system . The relay I used was a recreation vehicle dual batter relay available for about $ 15.00 ,hope this may help the people who are using automotive alternators that remain engaged

[airguy]

This is a good story to add to the pile dealing with EarthX batteries - if the choice is made to install an EarthX, you absolutely MUST have a positive control method for the alternator field, and ironclad overvoltage protection like a crowbar circuit.

[EarthX Lithium]

Originally Posted by climberrn

Spoke with Kathy at EarthX this morning also. She was not sure of their cut off voltage and couldn't transfer me to anyone that could. She did direct me to the website that says what you posted. The battery will be bench tested tomorrow also. If the battery OV protection is good to 40v, and the Dynon system has been tested to 80v, then I would suspect the battery has some damage also.

The battery was not providing current a few seconds after the incident. It was working on the ground after shutdown. Not sure when it came back online. Was not a good time to troubleshoot when we were looking for a field, day, VFR with a running engine after smelling electrical smoke. They say hindsight is 20:20. Hopefully I won't get another chance to do this again!

I'll update tomorrow evening with more info.

I understand there is still information being gathered but it would appear the regulator failure has been confirmed.

Our receptionist was not able to answer the questions (I was still traveling back from Sun N Fun and you did not speak with me) and did direct him to the website www.earthxbatteries.com to seek information in the manual until a qualified technical person could contact him back if he desired. There is also information in the documentation tab under FACT SHEETS that might also be of interest too.

When a regulator fails, high voltages are possible which is why we strongly recommend having over voltage protection. B & C alternators provide this and so does Plane Power alternators. There is not a certified aircraft out there without this protection too. You can add this safety feature to your plane for a minimal amount of money. (B & C offers a crowbar overvoltage product for $40) If you have this additional layer of protection, it would have automatically taken the alternator off line so that no damage would have happened. Without this level of protection, it is up to the pilot to manually take the alternator off line but the time lag could be enough to cause damage to your electronics.

Has the alternator manufacture been contacted? What did they say about the the failure modes and how high can the voltages go and at what RPM's? I also would ask the question if they have the over voltage protection for the supplied regulator. As Dynon stated earlier, their equipment is protected to 60V. If your alternator can put out more than this during failure, you do not have protection without an over voltage protection circuit.

[Alan Carroll]

Originally Posted by airguy

...which still would not have helped in this situation, since the battery terminals themselves went cold due the BMS cutting them off.

Good point, and a good example perhaps of unanticipated consequences of a design change.

[DanH]

I hadn't thought about it before but this may be part of the reason that Lightspeed specifies that their ignitions be connected directly to the battery terminals.

...which still would not have helped in this situation, since the battery terminals themselves went cold due the BMS cutting them off.

That's a very interesting observation.

The subject airplane didn't have overvoltage protection....but would it make a difference in the case of a battery-fed EI? Here it seems like a race. Given an overvoltage event, will the EarthX shut itself down before the crowbar can take the alternator off line?

Can anyone offer an accurate response time for each system?

[EarthX Lithium]

Originally Posted by DanH

That's a very interesting observation.

The subject airplane didn't have overvoltage protection....but would it make a difference in the case of a battery-fed EI? Here it seems like a race. Given an overvoltage event, will the EarthX shut itself down before the crowbar can take the alternator off line?

Can anyone offer an accurate response time for each system?

Great question! B & C Alternators state the overvoltage protection is at 5 milliseconds, the EarthX protection does not engage until 1 second.

[Chkaharyer99]

The EarthX users manual states in part;

"Aircraft over-voltage protection is strongly recommended (i.e. over voltage crowbar circuit)"

The use of an EFIS alone as a battery fault indicator seems counter-intuitive for reasons identified in the ops original thread whereas he lost the EFIS.

The EarthX LED fault indicator seems like a more robust fault indicator partially because it is designed to work with the battery off line whereas the EFIS may not.

To paraphrase, a continuous flashing light indicates greater than 15.2V defined as an over-charge (due to faulty charging system). If in flight, shutoff charging system off immediately.

Shutting off the charging system could be automated by use of aircraft over-voltage protection such as a crowbar circuit commonly found in Planepower alternators and B&C regulators.

What we don't know and need to know is the speed in which the EarthX battery will shutdown when it sees voltages greater than 15.2 volts.

It would also be good to know the speed in which the Planepower alt will go offline when the crowbar circuit detects a fault.

Joel,

I am grateful you got down safe and shared your story. What I've learned has served to make me safer through having a better understanding of how all this stuff works. Best wishes in getting it all back together.

Thank you,

[Carl Froehlich]

Originally Posted by rv7charlie

Joel, if the alternator really is set up for external regulation, and you turned off the field with the field CB, there's no way for it to continue producing current.

If it's actually an internally regulated model, it may or may not respond to removing voltage from the ignition (control) terminal. Some older internally regulated alternators will not come on line until voltage is applied to the ignition terminal, but will continue running after ignition terminal voltage is removed.

Either way, overvoltage protection is a very good idea. Are you on the Aeroelectric list?

Charlie

I can verify that for the Plane Power alternator, you pull the source voltage breaker and the alternator turns off. This is how I op test my B&C backup alternator.

As has been previously discussed, simplistic power distribution designs that do not allow for major component isolation present good opportunities for fairly straightforward upgrades to provide for isolating failed or questionable components.

Is the conclusion from this discussion that everything else being the same, if this plane had a standard Odyssey battery the result would not have been this extensive damage?

Carl