Earth X Battery Warning!!!

[SuberAvid 617]

My lizard brain finally kicked in and I remembered where I bought the Crowbar for OV protection:

http://www.bandc.aero/over-voltageprotectionmodule.aspx

They also have PM (permanent magnet) kit which will work on Rotax and Jabiru.

http://www.bandc.aero/pmovfilterandovprotectionkit14v1-1.aspx

 

Thanks for the info Paul.  It looks like a possible solution.  I am still not exactly sure what caused the overvoltage issue for me.  The situation first happened when I was coming back from scouting for sheep last year.  I made the best decision I could have by not doing anything and just flying the plane for the next 2 hours with the voltage bouncing all over the place and my warning lights flashing (not a comfortable flight).  My electronics are protected from overvoltage in their circuitry and I added it on the comm circuit as well so they survived just fine even though they tripped off a couple of times.  The engine continued to run just fine.  When I landed and shut things down I could not get the master solenoid to trip back on for a couple of minutes and it was very hot.  So I replaced the alternator and the solenoid thinking that was the problem.  I flew it for another 45 minutes or so and it started doing the same thing, so this time I figured it was the EarthX battery.  I replaced the EarthX with my old PC680 and flew it; it started the overvoltage issue again within about 30 minutes.  I then started looking at the way I had my alternator wired compared to Jacks and figured out I didn't have a ground to one of the terminals that Jack had so I added the terminal ground and the voltage stayed perfect.  I also wired up one ignition and one fuel pump direct to the battery and bypassing the master solenoid so I could switch these both on and shut down the master and the engine would continue to run but It would be without power to anything else.  I tested my system on the ground and the engine kept running just fine when I switched to battery only and shut down the master.  I figured I had it solved and it all worked fine for another 15+ or so hours and then one evening it started doing it again.  I was pretty near Big Lake airport at the time and not too worried since I had my new system in place; as I got near the airport I thought I would just switch over to battery only to land it; I made sure I had the battery direct ignition and fuel pump on and shut off the master.  The engine instantly died.  I switched the master back on and nothing.  I learned the prop will keep spinning for quite a while in the airstream but all combinations of switching would not reset the battery power.  You only get one chance to do your landing in that situation; I was lucky that I barely got to the runway and ended up landing a little sideways as I was trying to get lined up with the runway but the only damage was a bent axle.  After a couple of minutes the solenoid reset and it restarted and ran fine.  (I didn't realized how much a person looks at the instruments for altitude, airspeed, etc. even while dead sticking it and since mine are all electronic...O.O...)

I went back through the electrical system and rechecked the double grounds to the engine block and added a separate ground the alternator body and ran the alternator grounds all the way back to the negative battery lug.  The one other thing that I found that might have been causing the problem was the capacitor I have on the alternator + terminal is mounted under the carb on that side and the wire to it was getting pinched between the capacitor body and the carb float bowl.  I couldn't tell if it was causing this to ground the terminal but I rerouted the wire to clear the pinched.  Since then I have had no issues with it but I would like to have a back up just in case I ever encounter that situation again (although I will be hard pressed to switch it over in flight as long as the engine is running).

The more I think about it though, the more I think it is the internal protective circuitry of the EarthX battery that was tripping out and the plane was running on the power being supplied by the alternator.  When I cut the master switch it killed the alternator and the battery was still tripped off, and it takes several minutes to reset; so understanding how the EarthX battery works is important.

The question then becomes would the Crowbar automatically kick off the alternator but would it do it faster than the EarthX battery tripped?  If the battery was tripped my engine would die without warning.  In that case the manual switch to the stand alone battery would be the best alternative since I could kill the master and then switch on the backup while the prop is spinning to restart it.  Still, it would not be a comfortable situation in deciding to do the switchover.

I think the Crowbar would be a great thing to have for the lead type battery but might not be for the EarthX due to it's protective circuitry.  Someone with the right equipment and knowledge could test this to see if the Crowbar would work faster than the EarthX battery but unfortunately that is beyond my capability.

Sorry for the long winded response but maybe you all can reason out what you think happened and what would be the best backup solution (it might be the Crowbar?)  Let me know what you think.

Randy

[wypaul 448]

I will be the first to admit that this is over my head.  I would ,if I were you, copy your post and present it to aeroelectric users group. Thanks for your detailed post. Maybe EarthX will respond with some insight into their circuitry that may shed some light into this.  Is your alternator internally regulated or do you have a stand alone regulator?

The crowbar does react in milseconds but with all of the variables in your situation I cannot say if it would do the job.  I will do some investigation for my own peace of mind.