T-Motor U8 and T-Motor ESC 70APro Power problem

Good afternoon

I have a heavy copter I am building with T-Motor U8 (environmentally sealed versions for bad weather) and a T-Motor 70APro ESC connected up to 2*5S (aka 10S) battery supply.

My first problem was I could not get them to work with the Pixhawk until I realised my obvious mistake - they are optic isolated ESC so no power. OK Fixed that only to find problem 2 - Sync problems. Lots of practice an research lead me to the 5V bec. I was supplying only a 3.3V BEC and moved to a 5V 2A DC/DC converter and capacitor for very clean supply. They only draw about 100mA all up so seems good now. No more sync problems - I think. These problem did not appear directly off the RC Receiver, only Pixhawk - but I think they were reasonable problems one I realised my mistake.

Which leads me to my last problem, which could be a form of Sync problem but it appears not just with the pixhawk but also directly off the RC Receiver. ESC have been calibrated.

Short version - Power up slowly between 0-50% and, although spin up is slow/gradual, continues correctly to gain power. Then from about 55% throttle power drops until it gets to 90+% throttle which then give me full power (more than the 50% mark anyway).

Feels very much like a sync problem, but nothing to do with Pixhawk.

Any suggestions? What other information is useful to help?



You need to be a member of diydrones to add comments!

Join diydrones

Email me when people reply –


  • Hello! I had the same problem, so thankyou for sharing! Grüße from Germany
  • OK Some good news. With help from a few friendly net folk, who suggested some programming problems with the ESC, specifically governor mode, I was able to fly the new copter a few feet without any issue. Now I need to make it more rugged and then tune it.

    Thanks all.

  • I am thankful that you posted this here. I am planning a similar configuration myself for longer flights in mapping applications. I am sorry I cannot provide an answer for your question. But I would request you to post some more details about your project if you can.

    • Absolutely. There is nothing secret about it so I will publish all I can when it is done. Short short version is it is about 1.2m, 28" prop, U8, 10S, home built aluminium frame, pixhawk. I will also be putting up our ground station and Iridium Tracker boxes which are all part of it.

This reply was deleted.


Laurie J. Troy liked Jasper Kueppers's profile
Apr 1
Timothy Miller liked Joseph Udofia's profile
Mar 18
Joseph Udofia liked Joseph Udofia's profile
Mar 3