This may be picking nits, but the "C" light really means "charging", not "charged".
If you connect your TM to shore power, the charger in the converter sets the system voltage. As it charges the battery, the system voltage is high enough that the "C" light comes on. When the battery is fully charged, the converter still sets the system voltage, and the "C" light will stay on.
If you now disconnect shore power, the reading will drop down to "G" very soon, even though you haven't taken any charge out of the battery.
To answer the inevitable question. When the battery is fully charged, a good charger will decrease its output voltage a bit, so as not to overcharge the battery. However, it still sets the system voltage high enough that the "C" light will be on.
This is normal, if not exactly helpful. However, it is good to know that if you pull into a campground without hookups, and notice that the "C" light is not lit, it doesn't mean your battery is 25% discharged (or whatever).
Bill
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