if u are using 1S-enabled ESC such as hobbywing 1s, you can adjust the cutoff voltage to stop the throttle when voltage is too low.
if you are using other ESC, u might need to add a 6v batt to the receiver and disable the ESC +ve wire towards the receiver. 2 years ago, I was using a LiFe 180mah receiver pack when using 1S Lipo on non-1S ESC.
Hope this helps.