my failsafe had no problem kicking in when someone turned their radio on as soon as it glitched the failsafe turned on and i believe the dynamite operates at a lower voltage(usage?) so when the battery dies the failsafe automatically kicks in meaning theres enough to run the failsafe but not the servos.one person at our track thought he was having problems with is failsafe engaging when it shouldnt said he had just charged the battery earlier in the day when he removed it everything worked fine so he raced it in the first heat about4-5 laps in it took off wide open jumped the track into the feild next door and hit a wall about 500 ft away as soon as it hit we knew it was toast a 3 week old savage with 200.00 in repairs all he had to do was recharge the batt. it turns out he never turned the charger on hooked it up but never turned it on.yes they really do work but there are other things that need to be done also(throttle return spring,inspecting your vehicle) that will prevent runaways.