General Electrical Questions: First in a Series

[lrobichaux]

The volume of recent threads on electrical modifications, failure modes, G3X alerts and back-up systems has caused me to really do a deep dive into the electrical system / schematics on my experimental NXCub. As such, I would really appreciate the group's collective wisdom on a series of electrical questions that I will post up. Will start with this one. The EarthX battery (ETX900VNT) has a pigtail wire that I understand will report an internal battery BMS fault. Mine is not connected to the EIS (it's just dangling on the wind), although the CC wiring schematics show that it should be connected. Would like comments on whether my understanding is correct and whether it's worth going to the trouble of connecting it to the EIS and programming the CAS message. Will post additional questions in the next few days.

 

[Neal]

The EarthX battery (ETX900VNT) has a pigtail wire that I understand will report an internal battery BMS fault. Mine is not connected to the EIS (it's just dangling on the wind), although the CC wiring schematics show that it should be connected

When installing my EarthX I asked Pete about this and he said not necessary since you're getting the voltage readings in the G3X so you will be alerted there of any abnormalities with voltage.

 

[Cactus Charlie]

The EarthX status pigtail sends more that abnormal voltage signals. A voltage scale, with or without alerting, cannot display all the fault codes.

That said, I think it is unlikely that any of the fault codes would be active with normal battery voltage and battery current.

The simplest solution is to connect the pigtail to a warning LED as recommended by EarthX.

 

[Neal]

I bought the LED. Never used it after chatting with Pete. I need to find it, I'll probably connect it to the ETX-104 for my ignition backup battery which has the pigtail too.

 

[ve6yeq]

My thoughts when I last looked at it was that all the information communicated by the LED had no inflight actions given the current voltage and current monitoring and hence for other than post flight data logging, there is no reason to connect up the LED,

 

[Cactus Charlie]

That quick reference does not list all the LED fault indications that are included in the EarthX Lithium Battery User's Manual.

However, I saw no urgency to enable the LED warning and have not done so yet. I suppose it might be prudent to check the built-in battery LED pre and post flight but I don't do that either.