Just curious how often every one changes there batterys out. on my ZX10 tx that came with the T-28, I just put new batts in it but it was still on the second LED( it had one more to go before the red) on my Super Cub the stock batterys didn't last that long I was flying the plane and got a warning beep from the TX so I landed the plane and changed out the batterys. what is still a safe voltage to use a battery? compared to the replacement cost of a plane batterys are cheap but if I'm tossing good batterys for no reason thats wasting money too. I guess the reason I'm asking is because my brother recently "parked" his spitfire from about 700 ft when he lost all control of the plane, as of right now the prime suspect is the batterys in the TX were dead and apparently he either didn't hear a warning beep or the TX for the spitfire doesn't have the same TX as the SC even tho they look identical Parkzone vs hobbyzone. but seeing the end result was a totaled plane (fuselade, wings, cowl,prop,spinner, gearbox and who knows what else will be bad) I think I won't be waiting for a warning beep anymore. I have a multimeter to test them what is the cut off voltage?