closetguy

My Feedback: (13)

Well here i am again asking questions, i have a R149dp rx that the throttle gets lock out and just the throttle nothing else,all control surfaces still work. if i put a ppm rx in the plane i get a real good range check 120 ft. or more.last time i tried a range check on the pcm rx i got 100 ft. but have not tried it sense i got the throttle lock out.my question do i have a problem in the plane or maybe a bad pcm rx? this something new to me and had to ask.
THANKS for any help.

Bass1

I once had a similar problem with my system going into "Battery Failsafe". Since I didn't set the battery failsafe to a predetermined posistion it just went all the way to idle (default). Instinctively I started moving the throttle stick from full to idle and back and that restored my throtlle function for" 30 seconds" as stated in the Futaba manual. Enough time to nurse the aircraft back to earth![X(] I initially thought it was a faulty receiver battery and I was close, it was a cheesey battery extension cable( insufficient gauge) that was failing to deliver power under load and causing the unit to go into battery failsafe (throttle cut). When I upgraded to a quality extension it alleviated the problem. It could also be a failing on/off switch.

skreamer

My Feedback: (5)

I experienced the same thing but the switch and extensions were fine. I had an extra battery (2 batt.&2 switches) laying around and stuck it in and the problem went away. It is in the FAQ on futaba web site (battery/failsafe).

closetguy

My Feedback: (13)

Bass1 and Skreamer,Thanks for the info.i just didn't know where to start.and i didn't set the
battery fail safe,i thought for me it was safer to lose the throttle than the control sufaces to lock in.and like you said i to moved throttle back and forth and regain throttle.
THANKS AGAIN!

Cobra1

My Feedback: (42)

The battery failsafe is built into the receiver and cannot be turned off. If your battery voltage, even for an instant, goes below the threshhold the receiver will bring your throttle to an idle. You bring the stick to the idle position to regain control. This tells me you have something wrong with your electrical setup, please investegate before you lose your plane.

I had the same thing happen to me and it turned out to be a bad switch. When a high current was needed, it got highly resistive and the voltage dropped. The receiver shut the throttle down. I thought I had a glitch, lockout, got hit, everything went through my head.

Read about the battery failsafe on the FAQ as suggested, you will be glad you did.[8D]

Bass1

As Cobra 1 suggested, "This tells me you have something wrong with your electrical setup, please investegate before you lose your plane" Good advice!!

Whirlyspud

It could also be that your setup is fine but the circut controling the bfs is screwed up.

I had this happen on an older rx.

Mike

skreamer

My Feedback: (5)

Are you using digital high torqe servos with a 4.8v pack or need a 6v pack? I had seven digital servos going when I had this condition happen w/6v and duplicated in flight testing about 15 times. First i replaced the switch then the battery then the reciever then added more battery. So like the other guys said check it out.

closetguy

My Feedback: (13)

I am using 5 cell 2500 AAnmh with a MPI switch with five 5985's. i have this same set up in two other planes with no trouble for the last two years. i just started to replace the switch and battery with something better and going to use 20 gauge wire every where.then i will pull a pcm rx from another plane and try if need be. i am REALLY GLAD FOR ALL OF YOUR HELP on this THANKS.i know a lot of guy's would not use the AA's but i have had good luck with them up till now,i get 5-10 minute flights and it will be at 6.3-6.4 i don't go any lower than that.
THANKS AGAIN

Zeeb

My Feedback: (41)

One of the problems that is cropping up with increasing frequency these days is the use of batteries with high internal resistance usually referred to as "impedence" which cannot provide sufficient current output under high loads.

Voltage and MAH ratings alone are not sufficient to tell you if the batteries can support the current flow demands of today's high performance high torque servos. You have to remember that a lot of these batteries are made by large companies for all sorts of electronic gadgets and what will work for most stuff may not have the ability to deliver the current you might need when doing say a snap roll.

I suggest you investigate what the impedence rating is on the cells in the battery packs you are using and do a bit of research/comparison reading on that. Also, you say that you've been using this type setup for two years now, how old are your packs? If they're two years old, that may be contributing to the problem as well....

One other additional consideration these days is that while going to the 20 ga. wire size will help, the choke point with our currently available hardware is the connectors in the servo/battery/switch wiring. Depending on where you look, the concensous of opinion is that the max current flow those can sustain is 3.5 to 4 amps. Of course momentary current spikes can be handled but if you look at the general rule of thumb that 100 oz. of servo torque requires 1 amp of electical current, then you have something to work with. In your case of five 172 oz. servos one could theroretically pull about 8.5 amps of power and even more if one or more of the servos is stalled. Obviously the connectors of a single power wire from your switch to the rx aren't going to be very happy with that kind of load. This is the reason you're starting to see some battery pack manufacturers offering two output leads from their bigger packs, then you get twice the amperage capability with dual switches providing some redundancy for the most common failure point in the system. Or you can do what I've chosen to do on even my 50cc size models, they've dual batts/switches.

Sorry to be so long winded, but you're getting into a real gray area of what's necessary vs. what's nice to have when it comes to power systems, I hope you get it worked out....[8D]

closetguy

My Feedback: (13)

Zeeb,thanks for all the good information and it's kind of what i thought was going on.about the battery not being able to to deliver all the amp's.plus i found i put a light ga. wire extension from battery going to switch(DAH)!and after i thought about it,it always happen after i would do blendes or inverted flat spins (all servos jam) in one dirrection, just like you said.so after all the info from everyone i think i found the problem or at lease i am headed down the right road.
never like the idea of lipo's battries you know always half to remove them to charge. but i am looking at the new ones the A123's.
Thanks again

Zeeb

My Feedback: (41)

I think you're right on target with the A123's!

I've been running Li-Po's in my foamies and Li-Ion flight packs as the volitility of the Li-Po's makes me nervous, but the Li-Ions have their own limitations and both require the use of regulators which can cause problems as well, just ask Mr. Somenzini....

I've picked up one of the DeWalt packs but not decided on a charger yet, so I can start playing with these batts a bit and get more familiar with them. Dick Hanson lives up the road from me a bit and he's been pushing these things since they came out, but since I don't currently have to replace any existing batteries I'm not in a hurry to implement them and mess something up. I do think these batteries will be the best answer to our power supply requirements not only for flight packs but electrically powered models as well.

closetguy

My Feedback: (13)

Guy's THANKS for all of your help.as all of you knew you can't run 5- 5985's on a 5 cell AA pack.now i know that also,i put a 5 cell sub c pack in and could not get it to go into fail safe,ran 20 oz. of fuel out with the all servo's jam back and forth to put on as much load on the battery and switch as possible and all is well now.when i tried the same with the AA pack it would go into failsafe with in three-four minutes.THANKS AGAIN
ENJOY!

Bass1