I recently bought a new lipo pack for my Tarot quad as I didn’t want to have to share the same battery pack between my two quads. The new battery went into my newest Tarot 650 Sport equipped with Tarot 4114-11 KV320 motors. The battery is a GOLDBAT 6S 7200 mAh 80C lipo with XT60 connector.
I charged it from 22.8V to 24.8V and took the aircraft out to the field. Power up was normal and armed okay after GPS lock. Takeoff was smooth and I was trying to get it to hover in Stabilize mode, but after about ten seconds and sank and landed. After taking it back home and revieing the log, I saw that the voltage dropped from 24.8 down to and below 19V which caused the battery failsafe to trigger:
I will charge up my other 10000 mAh Lipo and try it out for a comparison. Unfortunately, the winds here are incredible and I may not be able to fly for a few days.
Fly a fully charged battery and from the flight log note the consumed mah. Then re-charge the battery and note the charged mah. Then calculate a new amps/volt value by: New amps/volt=(old amps/voltcharged mah)/logged mah*
So, I have two Tarot 650 Sport quads. Tarot 1 went through a painful development teething process - suffered several crashes and has since been repaired after some wiring was damaged due to hex screw threds cutting into the insulation. It has its own issues right now - motors not running smoothly resulting in some wobble and excessive vibration, but I Can manually control it. I will be troubleshooting that problem later.
Tarot2 was a more conventional and successful build and had a very good maiden flight using the 10000 mAH Lipo I used on TArot1. After buying the 7200 mAH Lipo I ran into this problem of extremely short flight due to the apparant excessive voltage drop. I charged the 10000 mAH Lipo to 24.82 V and put it on Tarot1 yesterday and I was able to fly it around for several minutes, so now I believe there’s something wrong with Taro2, not with the Lipo pack.
I am going to pull the log files from both aircraft as well as the complete parameter trees and compare. At this point, I don’t know if I have a hardware or software problem. Also, I intend to charge up the new Lipo and put it on Tarot1 and see how long it flies.
5 amps with a quad weighing at least 2 lbs? So theoretically, with a 10AH quad, your Tarot can fly for 2 hours? Really? Do you believe this data? I smell something is wrong with everything, and you don’t even realize it.
Please check and recalibrate the Battery Monitor, make sure everything is correct so we don’t get this nonsense data.
I don’t have a current meter for calibrating the voltage/current monitor. And no, I don’t accept the 5 amps as shown in the graph. But I tested both Lipo packs on my other Tarot quad that has more powerful motors and it flew for several minutes, so I have eliminated the Lipo as the culprit.
When I built the first Tarot quad, I wanted to avoid undesirable inductive effects due to having long DC wires from the power distribution board to the ESCs, so I chose to mount the ESCs within the body of the aircraft. The problem was that there isn’t enough room to accommodate the ESCs and the AC line connections going out to the motors. So I chose to add a third plate (deck) - bottom deck contains power module, power distribution and ESCs; second deck has connections to the motors as well as the gimbal controller; the top deck is for all the flight electronics.
For the second Tarot, I decided instead to revert to Tarot’s recommended construction and mounted the ESCs underneath the motors, thus eliminating the need for an additional deck. This aircraft’s maiden flight went very well - nice and stable. But I have had only a single good flight out of it. Last night I tried to run the motor test from Mission Planner and got really bad results - individual motors spun very slowly and all four motors hardly ran at all. With the propellers removed, I powered up the aircraft, armed and tried to throttle up - two of the motors wouldn’t run at all.
I have broken down the aircraft and tried running each motor with it’s ESC connected to Ch 3 on a spare receiver - got one motor to run fine. Disconnected power, connected to another ESC but when I powered up, there was no power going to the receiver. I measured the 5 V connection on the power distribution board and it measured less than a volt.
So, now I’m thinking of replacing the power distribution board and ESCs. I’m thinking of fabricating an ESC holder and slinging underneath the body in order to keep the lines short from the pdb to the ESCs and extend the control lines to the motors.
You don’t need one. Simply follow the instructions provided. It’s how it’s done. But, you have to fully charge the battery each time, not 24.82V for a 6S, for it to be correct.
Is this behavior reproduceable? What power distribution board you are using. What was all connections of the board espacially on the 5V. If the regulated 5V out drops mostly one of the connections is taking to much current. So the failure will be not initially the power distribution board but it can be damaged if it is not short circuit proof.
During troubleshooting, I found something wrong with the MATEK PDB I was using so I replaced it. A subsequent test flight produced the same result - smooth takeoff, extremely smooth flight but an emergency landing after about only ten seconds.
Last night, while researching what could cause this problem, I ran across several people over the years who had similar issues. On in particular struck me - he disconnected all peripheral connections from his PDB. THis lead me to wonder if I need to do something similar.
My other Tarot uses a MATEK board that BED circuitry - 5V, 10V and 12V, as I recall. I use the 5V to power the receiver, 10V to power the landing gear controller and the last to power the gimbal controller. That particular board is no longer available and the one I’m currently using only has %V ans 12V BEC with pads to accessing the 6S power driving the motors. I am using the 5V for the receiver and 12V for the landing gear controller and 6S power for the gimbal controller which can tolerate the higher voltage.
I just discovered that I really don’t need to provide 5V to the receiver as it is getting power from the Pixhawk; I may just leave the power disconnected from the PDB to the receiver. I’m also thinking of disconnecting the gimbal controller from the PDB. I can use a separate small 2S or 3S lipo to power the gimbal, but for troubleshooting purposes I may just remove the gimbal temporarily.
This will leave only 12V going from the PDB to the landing gear controller. I won’t get to test fly again after making these changes due to the weather. In the meantime, I’d like any feedback if I’m on the right path before I begin unsoldering connections.
This Tarot quad really flies nicely - as stable as my old DJI Mavic. I’d really like to solve this problem!
The LIPO is new, and I tried it on another Tarot quad with no problems with power consumption. I have unsoldered the connections to the gimbal controller and will attempt an experiment today. The weather is not conducive for flying so I will secure the quad with weights and throttle it up and see what the voltage drop is.
I just completed a static test. For comparison, here is the voltage graph when I tried flying in the field with the gimbal controller connected as well as the 5V going to the RC receiver:
If you run static tests you can parralel measure the voltage on PDB IN and OUT.
Your pictures only shows voltage but no current so at the moment these pictures are not so informative
