I didn’t say that RC has auto discharge circuits. It’s my observation that when you leave your RC for long, battery discharges to lower values. Not sure if that’s true for brand new batteries or it’s there in all batteries left connected to electronic switches.
OK, sorry for the misunderstanding. I read too much into your statement I guess.
After thinking more about this more, the OP saying he was guessing at 30%, it could be he had one LED showing which was interpreted as 30%. But one LED could be much less, I'm not sure. I have never let any of my RC's get below 2 LEDs of charge, so I don't know what happens when it discharges all the way, other than the GO4 app warning you with a red banner the RC battery is getting low. I don't know how many LEDs mean low battery, but I assume it's one LED when the RED banner appears in the GO4 app. I've seen that shown in this forum, but I've never experienced it. I would think the LED should blink when it's too low for comfort, but again, I don't know because I've never been there. The OPs interpretation of the LEDs for 30% and 6% has me a bit curious.
It's common knowledge that if the flight battery charge gets too low from sitting too long, the battery won't take a charge. I think that's because the "smarts" in the battery need a certain level of voltage to turn on the charge circuit, I would assume. It's known that when you get a battery that's so discharged that it won't take a charge, it can be revived with a little work. You have to take the battery apart and manually charge each cell of the battery by bypassing all of the charging "smarts", putting a charge directly to the wires coming direct from the cells. Once you charge each cell to a nominal level, the flight battery will charge normally again in the traditional way. There is a guy on ebay that sells NEW batteries in this "won't charge" condition for about $35/ea. If you take them apart and manually charge the cells, you can revive the battery and have a perfectly good battery for cheap.
However, in the RC, since the battery doesn't have same "smarts" of the flight battery, it's unclear if the battery gets into this same type of "won't charge" state or not. Since the RC is so easy to open up, easier than a flight battery, I would have suggested the OP try to jump start the battery manually in an attempt to revive it, just to see what happens. However, to do this you need a charger with the right capability (voltage) to charge a single cell at a time. In the case of the RC battery I'm not sure if individual cells are easily accessible like in the flight battery that supports equalization of the cells during charge. You might have to unwrap the battery to access individual cells.
