Receiver Battery Failsafe

[Mark_T]

I'm sure someone knows more about this than I do, but as I understand it, the original purpose of the Futaba battery failsafe option was to cut the throttle to a preset value as a warning that something was wrong, you then could regain control and land safely. The purpose was to make sure you knew when your flight pack was running low.

It was originally only available on the CH3 and it only cuts in when the voltage goes low and stays low so momentary drops don't trigger it.

This option has limited use these days when few of us use flight packs that would drop low enough to trigger the warning (about 3.8V I think) and it was never intended to be any help in the case of catastrophic loss of power, merely a warning that your flight pack was running low ...

[Granpappy]

Evening Mate.

Very valid point and most likely no, as the receiver will be rebooting, it will certainly not be thinking about moving the servos to any failsafe positions. Also once it was back up & running, it would then have to relay these commands to the FBL unit. We're only talking miliseconds, but in reality that ground is fast approaching

Ian

This is a link to how battery failsafe used to work on an older discontinued transmitter.

Futaba® 6X/6X Super Radio System Frequently Asked Questions (FAQ)

The 14SG is different because you can select any or all channels to respond to battery failsafe. If you are going to use it then then the best option would be to have it off on all channels except throttle. That way when the condition arises you still have control of the model in every way except throttle. You would then need to reset throttle so that you have motor power available for a controlled landing.

The key point to remember is that the battery failsafe voltage threshold is higher than the receiver re-boot voltage. If it was not, then the whole safety feature would be pointless because nothing would respond whilst the receiver was re-booting.

3.8v used to be the threshold for 6v receivers, re-boot voltage would probably be below 3v. I've no idea what the threshold is on 8v receivers which is what I use. I cant find any info on it.

[trillian]

Thanks Sheryl. Is this from CAP658 or BMFA?

That is from the BMFA but it may be in the latest CAP658 as well.

[Granpappy]

This option has limited use these days when few of us use flight packs that would drop low enough to trigger the warning (about 3.8V I think) and it was never intended to be any help in the case of catastrophic loss of power, merely a warning that your flight pack was running low ...

Yup I guess it's pretty academic these days with modern sbec's and 2s Lipo standalone supplies through regulators and ultra guard back ups etc.

My only concern was whether you are legally bound to activate a built in transmitter safety system in order to successfully claim on the insurance if the worst should happen. That question has been answered so happy days.

[George J]

Ian,
That's a good point, the most convincing argument I've heard so far. I guess if you're doing smack and the servos are to the extreme a lot of the time, it makes sense. Interestingly I've just looked up the VBar Control failsafe options and there are none. It goes to hold and that's it.

"Attention VBar Control’s pre-programmed Fail Safe-Settings will set the servos to hold and the ESC/trottle servo to the known motor off-position, both if the connection between satellite and VBar is interrupted and if the radio connection is interrupted or broken. This way, the energy is taken out of the system as much as possible, and the model is left on a hopefully predictable trajectory."

I think servos held and engine/motor to off as on Vbar Control fail safe is the best of a bad situation, it at least keeps the heli going in the same direction before the power failure up to a point but with the engine/motor cut so the heli will be at least a bit more predictable than if the servos go to centred.

[coolice]

Hey All.

As we've covered at the end of the day it doesn't matter what happens, as an unguided heli is a risk. For me, I'd rather have the controls go to neutral to slow the models trajector down than carry on in it's direction of flight. I've seen too many displays where the model is coming towards the pilot/spectator line and a failsafe here with last position hold could be a real problem, as by the time the pilot realises he doesn't have control it would be over their head.

I've always been dissappointed with Mikado at not offering the full failsafe options when using Spektrum sats on their FBL systems, the minimum required is throttle I know, but I'd like the option to program all channels. In my case I never run sats connected directly to my Vbar's for a couple of reasons.

Ian