MOD Upgrading the ignition backup battery in a Carbon Cub E/FX-3 (EarthX ETX104)

[Neal]

I pulled the battery and it’s on the charger and appears to be taking a charge. Fault light is out.

 

[Cactus Charlie]

The fault light was not on initially

No voltage available to drive it or the BMS.

 

[lrobichaux]

Out of curiosity why are you guys shutting off Master before you go to idle cut off? I’m going cut off before master off. What am I missing?

I have the same question. Please enlighten us.

 

[Neal]

Yes, I go AV and MASTER off prior to shutdown.

As to the last flight data it shows the same as FlySto, it appears my time from AV/MASTER off to shutdown was too fast for the G3X to record. Maybe AXIS records faster

Attached is the last flight prior to yesterday. I checked several prior flights, all data log the same, V1 and V2 read until the log stops.

 

[Cactus Charlie]

That data log stops with engine still turning at 830 rpm. Log samples at 1 Hz. You must have fast hands to get all the power off that quickly.

 

[Neal]

When the engine stops IBBS goes off. When I'm in the hangar I turn it on again to record times.

 

[Cactus Charlie]

When the engine stops IBBS goes off. When I'm in the hangar I turn it on again to record times.

Your choice but you lost data that could have been useful in finding out when the fuse blew. Why not leave it on for a few minutes after engine stop?

If the IBBS is in good condition it will power everything connected to it for well over 2 hours.

Do you have the log that was recorded in the hangar or was there no log for that switch on?

 

[Neal]

I just got off the phone with Keegan at @earthxbatteries tech support and discussed the situation. It seems there is likely a parasitic drain on the ignition backup battery or potentially my amp meter (loop) that was installed, who knows, but sitting for 2.5 months likely drained it. The BMS should kill the battery at 10.8V and that effectively cuts off current to the terminals. It sounds like when I got the charger on it and it rose above 12.8 I think he said that likely cleared the fault light and it should charge back up. We're not sure if there is a failed cell, it is under warranty and I could send it in but I'm going to do a load/capacity test on it and see how that works first.

I then inquired about the new offering coming out. He said it was supposed to release last week but there is a parts supply issue so it could be any day from what it sounds. He is not in engineering but he thinks it's going to be a different form factor like other offerings and potentially in the 8ah realm with a weight of 2 lbs and a simpler design than the other ones we discussed here in other threads or this one. I mentioned to him our need for managing charge current and he didn't have an answer for that but for me to email him to pass it on to engineering.

 

[Neal]

Your choice but you lost data that could have been useful in finding out when the fuse blew. Why not leave it on for a few minutes after engine stop?

Depends on bladder state

Do you have the log that was recorded in the hangar or was there no log for that switch on?

I didn't see it, I updated my local file with everything from the card and checked several files from the last flight date to find that data.

 

[Cactus Charlie]

Back in 2022 I asked Garmin about the conditions required for data logging to start. The answer was -

"The data log begins when at least one of the below criteria are met -

· Have a valid GPS fix

· Engine running

· System is in the air

· Autopilot is engaged"

GPS fix is also important for making screen shots in the hangar. If no fix the files are tagged with date and time starting at system creation date.