You can see what the voltage is for each light.
It seems the top light has nothing to do with the battery and more to do with the converter. Any voltage over 13.2 volts will turn on that light.
When fully charged, the battery will hold that voltage until something starts to draw amps out. Once the voltage drops below 13 volts (or so), the top light will go out.
Just like the other "indicators" on that goofy panel, 2/3 light does not mean 2/3 battery. Its more like 98% battery capacity remaining.
It takes a LONG time, (unless your inverter is making coffee
- don't ask me how I know), to drop from 2/3 to 1/3. This has not happened since installing the TM-2025 so I don't know what the actual voltage is at that point. I suspect with resistor tolerance being the cheapest they could buy in that goofy panel, that it would vary A LOT anyway.
I will put that on my "to do" list next time I dry camp.
Lou and Laura with Bella - German Short Hair Pointer
2008 GMC Sierra 2500HD Crewcab SB Allison Duramax
2010 Flagstaff 8526RLWS - Superglide 3300
HAM CALLSIGN - KC3FFW