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Using 7.4v. Lipo with flysky rx

G-Man

Junior Member
Messages
958
Location
Pittsburgh,PA
Hey Rampage MT guys. Do any of you use a Flysky it4s transmitter and receiver? I have one and want to use a 7.4v lipo to power the rx. Anybody use this setup? Seems my hitec steering servos don't like the 6v nimh hump pack. Thanks
 

prostock

Senior Member
Messages
214
Location
New York
Hey Rampage MT guys. Do any of you use a Flysky it4s transmitter and receiver? I have one and want to use a 7.4v lipo to power the rx. Anybody use this setup? Seems my hitec steering servos don't like the 6v nimh hump pack. Thanks

I don't have that radio but if you want to use a LIPO to power your RX you should use a BEC and set it to 6v
 

G-Man

Junior Member
Messages
958
Location
Pittsburgh,PA
I don't have that radio but if you want to use a LIPO to power your RX you should use a BEC and set it to 6v
Ya I thought about that. I may get one. But it seems the servos crave higher voltage. My RX states 6.5v max. I can set the kill switch for lipo low voltage shut off. Plus my radio warns me if the rx voltage goes low. I don't know, I have a spare rx if it fries. My steering servos are frustrating me. I run 2 hitec 5765. I swear they are adjusted/synched properly. I get no nimh battery life since swopping The steering quits working 10 minutes into running it.. I used to get at least a tank from the stock ones.Seems some have no problems with them, but I am. That is why I am going to a lipo. Thanks for the input prostock!!
 

prostock

Senior Member
Messages
214
Location
New York
Ya I thought about that. I may get one. But it seems the servos crave higher voltage. My RX states 6.5v max. I can set the kill switch for lipo low voltage shut off. Plus my radio warns me if the rx voltage goes low. I don't know, I have a spare rx if it fries. My steering servos are frustrating me. I run 2 hitec 5765. I swear they are adjusted/synched properly. I get no nimh battery life since swopping The steering quits working 10 minutes into running it.. I used to get at least a tank from the stock ones.Seems some have no problems with them, but I am. That is why I am going to a lipo. Thanks for the input prostock!!

G-Man you can look into Futaba receivers the new ones are rated for 7.4v http://www.futabarc.com/receivers/surface.html
 

G-Man

Junior Member
Messages
958
Location
Pittsburgh,PA
G-Man you can look into Futaba receivers the new ones are rated for 7.4v http://www.futabarc.com/receivers/surface.html
I emailed Futaba today. They seem to think the Flysky will not work with the Futaba rx. I looked at every rx Flysky has that is compatible with my tx. None of them have have higher than a 6.5v. max. So I either get a bec or throw away my 3 month old radio system for one that is lipo capable. Or and a big OR... Just say screw it and run the lipo directly to the rx. My luck I chose a radio system that is limited. And very limited support, Flysky's phone number is directly to China. What?? No USA sales and service? BS.. I can't get an email response or fb message either.
 

designed2survive

Senior Member
Messages
1,005
Location
MA
10 mins of run time? That very low!

The issue could be:

1- with the servo themselves
2- steering setup (binding, resistance, restricted steering movement, servos fighting each other.
3- bad battery

Did you tried a different known good battery pack?
 

G-Man

Junior Member
Messages
958
Location
Pittsburgh,PA
10 mins of run time? That very low!

The issue could be:

1- with the servo themselves
2- steering setup (binding, resistance, restricted steering movement, servos fighting each other.
3- bad battery

Did you tried a different known good battery pack?
It probably is the servos fighting each other. I have 2 brand new hitec 5765 installed. I did and/ or am having a hard time getting the adjustment down. I got it where it seemed fine ran the truck for 5 minutes and the steering would slow down. Is there any tricks to getting a good adjustment? Funny thing is that the servos don't get hot to the touch when this happens. And my radio warns me of low voltage when I steer. I have 2 2500 mah stock packs. Tried both, same thing happens. So I assumed it was battery power problem. This is why I went lipo. Haven't set it up yet..
 

G-Man

Junior Member
Messages
958
Location
Pittsburgh,PA
Well here I am still pulling my hair out. I went to the Lhs and got a castle bec and linked it to my pc to adjust the output voltage to 6 then hooked up the lipo. Installed in the truck loosely to make sure I am good to go. I still have problems. I have no steering or throttle now. Then I remembered that the last time I ran it I had to use the kill switch twice because of it being stuck full throttle. It was fridged that day so I lubed the linkage and it seemed ok. I was more concerned with the steering. Well today the throttle wouldn't move. I put a known new servo in its place and bang throttle now works and the steering works also. I did run through snow that day. Guess it fried the hitec hs 5645 I had in for the throttle. It's 4 months old. Another guess going by how stiff it is to manually turn the servo that it is bound up inside and was just chewing up the battery. I'm not sure if I want another hitec.
 

G-Man

Junior Member
Messages
958
Location
Pittsburgh,PA
No problem, here is an article that shows you how to power the servos direct while using the BEC to power your receiver. http://www.fingertechrobotics.com/how-to_servo_voltage.php
Ok man this article has me back to running again. 1 large steering servo with 7.4v straight from the lipo to the positive lead on the servo, ground and reference wires to channel 1, Castle BEC reducing 7.4v to the 6.5v max. that the rx can handle. New throttle servo also. I took the time to tear each servo down and waterproof them to the best of my ability, and set all the end points. Hopefully my servo problems will be done for awhile. I will be one happy man Saturday when I get the chance to try it out. Thanks to ALL who helped with all the ideas!!!!
 

fordgtr06

Well-Known Member
Messages
69
Do you have any pictures of your set up? I'm looking to do the same thing you are doing but am unsure how everything hooks up. I understand you need to hook positive of each servo to positive battery lead but do you have to solder these in or so they have a connector? Also does the bec go between the battery and rx I'm assuming? And which battery did you go with and did it fit without modifications ? Thanks in advance.
 

G-Man

Junior Member
Messages
958
Location
Pittsburgh,PA
Do you have any pictures of your set up? I'm looking to do the same thing you are doing but am unsure how everything hooks up. I understand you need to hook positive of each servo to positive battery lead but do you have to solder these in or so they have a connector? Also does the bec go between the battery and rx I'm assuming? And which battery did you go with and did it fit without modifications ? Thanks in advance.
I ran a castle 10 amp bec. Soldered appropriate lead ends onto the bec pos. and neg. wire ends so it can hook to the lipo. On that same solder joint on the bec I ran another separate wire from the positive to the positive on the high voltage servo by gently removing the wire end from the plastic connector. Then soldered a male end on the new wire I ran from the bec slid the two wires together and shrink tubing done there. The other two wires stay in the servo connector and plug into the receiver as usual. Then the bec plugs into the switch which you will have to swop ends to match the bec servo type wire end. The bec needs to be set to your receiver and other servo etc. max voltage using a laptop or a portable programming card they sell. It really wasn't that hard just took me a little bit to get a grip on how I wanted to do it. I will put up a picture
 

fordgtr06

Well-Known Member
Messages
69
I ran a castle 10 amp bec. Soldered appropriate lead ends onto the bec pos. and neg. wire ends so it can hook to the lipo. On that same solder joint on the bec I ran another separate wire from the positive to the positive on the high voltage servo by gently removing the wire end from the plastic connector. Then soldered a male end on the new wire I ran from the bec slid the two wires together and shrink tubing done there. The other two wires stay in the servo connector and plug into the receiver as usual. Then the bec plugs into the switch which you will have to swop ends to match the bec servo type wire end. The bec needs to be set to your receiver and other servo etc. max voltage using a laptop or a portable programming card they sell. It really wasn't that hard just took me a little bit to get a grip on how I wanted to do it. I will put up a picture


Thank you for replying. I think I understand what your saying. Pictures if you had them would confirm what I'm thinking in my mind. And I'm glad the battery will fit with no problems. Thanks again.
 

G-Man

Junior Member
Messages
958
Location
Pittsburgh,PA
Thank you for replying. I think I understand what your saying. Pictures if you had them would confirm what I'm thinking in my mind. And I'm glad the battery will fit with no problems. Thanks again.
The red wire is direct 7.4v. goes to the positive wire on the high volt servo. The other servo plug goes to the receiver battery input (channel if you wish). This is now regulated down to 6 volts so your receiver isn't over powered.
 

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G-Man

Junior Member
Messages
958
Location
Pittsburgh,PA
The red wire is direct 7.4v. goes to the positive wire on the high volt servo. The other servo plug goes to the receiver battery input (channel if you wish). This is now regulated down to 6 volts so your receiver isn't over powered.
Forgot to put the lipo in the pic. Here it is..
 

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