Hello
and thank you for your great job in this community.
Today I had an unexpected crash with my quadcopter after 11 minutes flight for the second time.
With out warnings from mission planer it fell from 30 meters like as rock.
Please help me to found the problem.
I have attached the log.
Thank you
Replies
I remember that the copter flew in position hold about 4-5 minutes . I don't know why log stopped at 17 sec.
Well, that may be symptomatic of a problem with the APM. I think your best bet is to try a different flight controller, one that you know works. Sorry I can't help any more on this mystery.
Doug
Thank you for your help.
Charilaos
From the Data Log, I can see that the throttle Out started to oscillate wildly, from off to full throttle, at the time of the crash. The Integrated Throttle signal (ThrIn) also dropped to zero briefly and then back on at the same time. ThrIn is the sum total of all of the flight control stability calculations that gets sent to the throttle control. The question is Why?
I can also see the fall from the sky on the altimeter so the processor was running at the time and recorded the trip back to earth.
Your battery voltage shows a normal LiPo discharge (you are running a 4S right?) all the way out to where the battery appeared to die. It started at 16.3v and dropped to 15.25 when you powered up the motors. Then the voltage dropped steadily, as it should, until it reached about 13.65. That's pretty much a dead battery for LiPo, 3.41 volts per cell. At that point the battery voltage starts to drop rapidly which is what yours did. Over the next few moments, the battery dropped to 13.05 which is a dead battery. You had consumed a total of 7032 mha of current from the battery. What was it's rating?
Vcc was rock sold the entire time at about 5.1 volts. I think what happened was you ran the battery down, and the FMU pulled the plug. My F450 did that on one of my early endurance tests. Fortunately I was only 4 feet off the ground when that happened. I suspect that you do not have any of the battery fail safe parameters set. You should set up you battery warning to 14.3 v or greater, and set the the Land or RTL fail safe to 14 volts. That way you will never run out of juice and you won't damage your battery from over discharge.
Hope this helps,
doug
The battery is 4s 16000mah 10c.. After crash saw 3.80 volt per shell. I think that means no empty battery right?
The first time that happened is 5 min hover flight.
According to the log, your battery got down to 3.26v/cell under load. It is not unreasonable at all for it to recover to 3.8v/cell once the load is removed. Given that you have a 16k mah battery, I am surprised that it died after only 7032 mah. The battery is either defective, or it did not get a full charge, or you flew it for 10 or 12 minutes before this fatal flight. In fact, It looks as though the charge was only at 50% or less of capacity. At 40 amps, I would expect no more that 20-24 minutes flight time on a fully charged battery in good condition. That is apparently not the case here.
I suggest that you give it a full charge, then put on a dummy load and measure the mah you can draw before dropping to 3.5v per cell. don't go below that or you can damage the battery (may have already happened, explaining the behavior you are seeing).
Doug
I am surprised because the battery had full charged in 4.20 per cell. With this battery it can fly 18-20 min and today I had the first flight with this battery.Also the battery have 5-7cycles only and never discharged less than 3.7 per cell.
Charilaos,
Are we talking about two different batteries? Because the battery involved in the crash was definitely discharged to 3.26 v/cell and the total current consumption was 7032 mah. When you said above, "today I had the first flight with this battery" How do you know it can fly 18-20 minutes if this was the first flight? Have you flown it successfully on a different copter?
In you initial post you said "Today I had an unexpected crash with my quadcopter after 11 minutes flight for the second time." Are you saying that this was your second flight on this battery without recharging? Or are you saying that this is the second crash with this battery? Please clarify.
I still stand behind what the datalog is telling me - the battery showed a perfectly normal discharge curve right up to the point that it ran out of juice. It must have been partially discharged when you started the flight.
Doug
Doug
we talking about one battery. It has 5-7 cycles and with specific battery yesterday I had the first flight.
Yes I am saying that this is the second crash with this battery and I have flown it successfully on a different copter with another pilot.(no pixhawk).
Charilaos,
You said that you had the first crash only 5 minutes into the flight. Do you have that data log as well? That would help to clear up some questions. There is no doubt that, with the second crash, the battery was at or near the end of its charge. I did observe on that data log, that right before the copter died, the current rose up from about 40 amps to 57, then dropped suddenly and the copter began to fall. I could not see any indication in the data log why the current rose the way it did. There was no throttle demand, the motor output signals did not rise up accordingly, nothing. I'd like to see if the same behavior happened on your 5 minute flight, and what the battery voltage was at the time. Please send along that data log if you have it.
Doug
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