Charge light stays on

Need just a tad more info.

The battery shows 13.8 in flight, but did it start normal on the ground and before you turned the key to start what did the voltmeter read?

What did you use to recharge the EarthX?  Discharged lithium batteries need a special charger.

Roger - I don't recall having seen the light on after starting the engine and while on the ground - I'd hope I'd see the light on, but cannot say for sure it was off.  Now, engine off, the battery shows 13.4V and 13.3V when I have all the instruments running and lights on.  I think it was pretty much the same before running the engine, maybe a little higher - I didn't notice anything unusual when I put the battery back in, but didn't note the voltage.

Tyler - I have an IMax B6AC charger, set up to charge LiFePO4 4 cell at 5A, which is well within the maximum charge-rate for the battery.  So, it is the appropriate charger type for this battery.

I'm going to try two things next - first run the engine with a different battery.  See if that makes a difference.  Second, isolate the battery while the engine is running (Master Switch off).  The voltmeter will still register voltage from the alternator, so I should be able to see if I'm getting charge to the battery (when it's re-connected).  I assume the alternator will continue to output current without battery voltage to excite it, but please tell me if that assumption is wrong or running the engine battery disconnected is a bad idea (i.e. I'm going to fry the regulator). I have the capacitor located as per Rotax wiring, so I believe that shouldn't be a problem. 

Steve

While your thinking about diagnostics here's something odd that was like your light being on. I have a friend with an Tecnam. His light looked to be on too when we were out of the hangar. Come to discover after looking around it was the sun coming through making it look like it was lit. Also make sure something else behind that light isn't causing false lit up indication. Might as well rule out everything and not just think the worst.

Now I am Confused. ???

>>>I don't recall having seen the light on after starting the engine and while on the ground - I'd hope I'd see the light on, but cannot say for sure it was off.  <<< 

The Light will be ON when the master switch is ON and the engine is STOPPED.

Observe the battery voltage before starting the engine.

12.6 = 100% charged.

12.2 = 50%

12.0 = 10%

10.0 = 0%

Your 12 volt discharge was Low but within normal limits and not damaging to the battery.

If the battery Voltage show 13.8 - 14.2, after starting the engine, The battery is charging.

Do not bother swapping the battery and do not intentionally run the alternator without the battery connected.

The light has nothing to do with the battery.

Under normal conditions, The voltage at the Rectifiers is much higher than the Battery, and the Regulator controls the difference.

The light indicates that the Voltage at the Rectifiers is Lower than the Battery, indicating that the Regulator is Not being powered and the battery is NOT being charged.

Engine OFF.  Light ON!  Is Normal. 

Engine ON, Light OFF. Battery >13.6 is Normal.

Engine ON, Light ON,  And/Or  Battery <13.6 is NOT Normal.