Originally Posted by WimH
I do not think not having the circuit will save your model, voltage tends to go down very fast when the battery is nearly empty.
I was just having that discussion with respect to my 9X which is powered off 2 18650 protected cells. The protection kicks in at 2.5V, and even if the pack was grossly out of balance it's hard to see the transmitter working with one cell below 2.5V. Maybe with the 9XR and a 3S pack that's not the case, and it would work even with one cell completely dead.