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DT700 and 4s batteries

F@lcon

Junior Member
#1
Hi, this article (http://flitetest.com/articles/tricopter-scratch-build) inspired me to buy 4s battery for my tricopter and now I am a little bit worried about burning my motors or ESCs. I use DT700, Turnigy Plush 18A, 11x4.7 props and 4s Turnigy 3000mAh LiPo. Had anyone tried to run DT700 with 11x4.7 prop and 4s battery? Isn't it too much? Should I rather use smaller props? Specs of DT700 says that nominal voltage for this motor is 11.1V and max prop size is 11x4.7 but for 3s battery. Thank you very much in advance.
 

kah00na

Senior Member
#2
Others will probably know better than me, but on my wooden bat bones tricopter, I'm running 4S batteries with SunnySky 980kv motors, 30 amp ESCs, and 10" propellers. It isn't the voltage that will kill your motors and ESCs but rather the heat they generate. I think the general rule is that if you can keep your hand on the motor/ESC for 5 seconds without burning them, then they should be fine. I wasn't sure about using 4S batteries my 10" propellers so I flew it around for a short amount of time, landed it, then felt the motors and ESCs to check if they are hot to the touch. They were barely warm. I put 11" ones on and it flew around like a rocket so I moved back down to 10". I was originally flying with 9" and after flying around for over 10 minutes, my motors and ESC were cool to the touch... not warm at all. That is when I moved up to 10" - even now they are barely warm. If I get more FPV stuff loaded on it (more weight), I may try the 11" propellers again if I need more lift. If I was guessing, I'd guess the 11" propellers are going to provide a lot of lift for your tricopter with 4S batteries.
 

xuzme720

Dedicated foam bender
Mentor
#3
You can double check the draw with a wattmeter for added insurance but heat is a sure tattle tale symptom.
 

Cyberdactyl

Misfit Multirotor Monkey
#4
Hi, this article (http://flitetest.com/articles/tricopter-scratch-build) inspired me to buy 4s battery for my tricopter and now I am a little bit worried about burning my motors or ESCs. I use DT700. . .
While I have learned a hell of a lot from Flitetest, especially David, their tutorials can be a little shaky. They have no qualms about crashing and trashing their craft as their Youtube videos attest. So while they indeed have wonderful ideas and designs, you really need to scrutinize what they tell you IF you want your multi-rotor to last.

For example, in the tutorial you linked, David tells you to not screw down on the props too hard against the bell one minute, but the next he is suggesting you use wood washers under the props for more friction. EITHER WAY, you are risking, and most likely will, put enough shear force on the grub screw to have it slide on the shaft in time to transfer that force to the bearing. Instead put a nut and metal washer under and over the prop to clamp.

In the same manner of planned obsolescence, the DT700 is not recommended for 4S, although it will probably handle it for awhile. If you want to use a Hextronik DT series motor with 4S get the DT850. It is designed for 14.8v.