[ZeroMax]

i want to ask about the importance of a failsafe, my LHS recommended that i should place a failsafe on my nitro truck because i'm not running on a reciever pack. would someone please tell me how one works/setup and if it is nessary to get one. if so what do you guys think of the futaba one? because that is the only one i can get my hands on

thanks

[always_opencarb]

when/if you lose connection with your truck it movers the throttle servo to the break poistion or what ever you set it to. or when you batts are about to die it cuts off the engine i think the ofna one is also good

[ZeroMax]

but i looked on the futaba website and it says the futaba one works different 'it will hold throttle control to a safe position for 30 seconds' does that mean if i don't retrive the car it will still do a runaway instead of cutting off the engine?

[Duster_360]

This is what the specs on TH says about that failsafe -
FEATURES: Fail Safe is a safety device that constantly checks the pulse signal
from the receiver by means of a CPU (Central Processing Unit) and
turns on a fail safe if the pulse is disturbed by interference.
When the power supply voltage drops, a battery fail safe function
turns on and moves the throttle servo to a preset position
(normally, idle/brake).
Compact and lightweight design does not affect servo performance
Responds quickly to interference, etc, and prevents loss of control
of model
Quick recall function quickly resets the fail safe function by
normal servo output signal from the receiver when the interference,
etc., disappears

So to answer your question - no, don't think it works that way. Looks like if you have interference, it activates as long as the interference is present, and it resets the failsafe if the interference stops, but your car will still be at idle or stop unless you have kept your finger on the tx trigger the entire time. If you've had a runaway, when you realize your rc is not responding, you quit with the tx and take off running after it, lol! Sometimes, translation from Japanese to English is not perfect. I'd trust Tower to have it correct.

[ZeroMax]

do you guys think its nessary to buy one because they are quite expensive and do they go wrong often?

[Duster_360]

The area where I usually run has a lot of powerlines. I had 2 runaways - after the 1st I talked myself out of buying one and then had the 2nd about 3 days later - got lucky again - ran into a ditch and killed the motor, no damage. I bought one. I use receiver batt pacs and I still run them. There are others that seems to be just as good that don't cost what the Futaba does. The orfna seems to be a popular one, its real small and it costs less.

I changed to FM and my radio now has one built in, so all I have to do is set it - I wouldn't be without one. You have a runaway and the motor goes WOT and you smack something solid, you'll spend a lot more in repairs than the failsafe would have cost. $20 is cheap protection for a several hundred dollar MT, but just my feelings on the matter.

[Graystar]

Originally Posted by ZeroMax

my LHS recommended that i should place a failsafe on my nitro truck because i'm not running on a reciever pack.

I'm sorry, I'm at a loss here...how do you power the receiver and servos??

[AreCee]

I think he means to say that he's using 4 AA batteries and not a rechargable Rx pack.

[AreCee]

I use both a TRS (Throttle return spring/devise) and a fail safe. Even then there may be a time when neither will prevent a runaway such as if the servo motor seizes up and locks in an open throttle position, the spring can't close it and the fail safe thinks that all is OK.

[ZeroMax]

thanks alot for the comments after dreading a runaway scenario i got an OFNA failsafe (instead of futaba) today cause it was cheaper by a margin and it was quicker and easier to set up. But the LHS mentioned that because i was using 4xAA batteries that the failsafe would kick in quickly after the start because AA batteries run out quickly is that a problem?

[Duster_360]

Alkalines voltage response under load is diff than a NiMh batt. The voltage on alkalines under load starts falling and just continues to fall until they are pretty much gone. A NiMh batt tends to hold a fairly constant voltage output under load and then quickly drop as the batt charge is gone. Thats why the NiMh rx pack is much better for an rc - you want as near to a constant voltage on your servos as you can get. Don't know how long you'll get before the ofna failsafe starts alerting you on low voltage with alkalines.

[ZeroMax]

i got 4xAA GP2300 NiMh rechargable batteries. does that the voltage will be constant?

[AreCee]

Originally Posted by ZeroMax

i got 4xAA GP2300 NiMh rechargable batteries. does that the voltage will be constant?

Yes, but you'll be underpowered at only 4.8V instead of 6V.