P4P RTK Power loss crash

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Hi,

We recently had a crash with our P4P RTK where it appears to have suddenly lost power at the end of a mapping mission using Pilot. It finished its mission, triggered RTH, yawed to face its home point then lost power and dropped directly down landing on its landing gear which both snapped off and destroyed gimbal/camera.

Ive had a look at the logs and it had 10 "GPS mismatch error" during the first few waypoints, and the previous flight has 40 of the same error and at least 1 for the previous 8 flights. I know this can be indicative of nothing critical or potentially a compass / GPS / gyro mismatch. I wouldn't have thought this would cause it to suddenly lose all power like that though.

Compass cal was done approx a week before crash and flight area did not change. No significant metal in take off area but was iron ore rich environment. Battery log looks fine no dips in voltage or cell misbalance and had 28% at time of crash.

Any help diagnosing or how to diagnose the failure much appreciated. I have the txt and dat logs and will attempt to attach them to this thread.

Thanks!
 
Ive had a look at the logs and it had 10 "GPS mismatch error" during the first few waypoints, and the previous flight has 40 of the same error and at least 1 for the previous 8 flights. I know this can be indicative of nothing critical or potentially a compass / GPS / gyro mismatch. I wouldn't have thought this would cause it to suddenly lose all power like that though.
It won't.
GPS mismatch errors are common false alarms and definitely have nothing to do with the power system.
Compass cal was done approx a week before crash and flight area did not change. No significant metal in take off area but was iron ore rich environment.
None of those would have any effect on the incident you described either.
Btw ... there's no need to recalibrate the compass, no matter where you are flying.
Battery log looks fine no dips in voltage or cell misbalance and had 28% at time of crash.
Any help diagnosing or how to diagnose the failure much appreciated. I have the txt and dat logs and will attempt to attach them to this thread.
The .txt file is what's needed.
Upload it to dropbox or similar and post a link.
What app were you using to fly with?
 
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Log file from RC of the flight that crashed.
 

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  • DJIFlightRecord_2023-03-20_[07-02-45].txt
    2.2 MB · Views: 81
Log file from RC of the flight that crashed.
Here's what a summary of the flight data looks like:

Loss of power incidents are frustrating because they usually don't leave any tell-tale clues in the data.
The drone is flying normally and then it isn't.
What the data can do is help eliminate potential causes.

When the data stopped, the drone was 120 metres up, well clear of any obstacles that could block signal or be a collision risk.
It had just finished the survey grid and was in RTH and hovering while slowly turning to face the home point.
Wind was light but not significant.

The battery had only 39 charge cycles.
Battery level was more than sufficient for the short flight to the home point and cell voltages were well above critical low voltage.

The current draw on the battery appeared normal for hovering.
Battery temp was warm at 67°C, which is probably normal in your part of the world.
Had you flown in similar temperatures previously?

There are no obvious red flags showing in the data.
We can only guess that either the battery or something in the power circuits had a sudden failure.
 
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Here's what a summary of the flight data looks like:

Loss of power incidents are frustrating because they usually don't leave any tell-tale clues in the data.
The drone is flying normally and then it isn't.
What the data can do is help eliminate potential causes.

When the data stopped, the drone was 120 metres up, well clear of any obstacles that could block signal or be a collision risk.
It had just finished the survey grid and was in RTH and hovering while slowly turning to face the home point.
Wind was light but not significant.

The battery had only 39 charge cycles.
Battery level was more than sufficient for the short flight to the home point and cell voltages were well above critical low voltage.

The current draw on the battery appeared normal for hovering.
Battery temp was warm at 67°C, which is probably normal in your part of the world.
Had you flown in similar temperatures previously?
Yes the ambient temp would have been around 40C for alot of this drones flights.
There are no obvious red flags showing in the data.
We can only guess that either the battery or something in the power circuits had a sudden failure.
Thanks for your help! We are going to attempt to get it repaired and ask our tech team to look for an obvious component failure.
 
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I had a very similar event with a P3 Adv. Screen showed "Critical Power Loss" on a fully charged battery, and the bird simply fell out of the sky. I could find nothing wrong. Needed to replace camera, gimbal arm and cables, as well as the 2 landing gear struts. Flew her again after the repair, keeping her about 2 Feet above my soft lawn, just in case, and it happened again. No damage this time! Tried my other, newer battery, and the same thing happened after about 5 minutes flight time.
Going to spend some time one of these next weekends and strip her right down to check all cables, connections, solder joints and battery contacts, just to see if I can find something obvious.
Fortunately, I have my other machine, a Mavic Pro so my work is not interrupted.
 
I had a very similar event with a P3 Adv. Screen showed "Critical Power Loss" on a fully charged battery, and the bird simply fell out of the sky.
In the OP's incident there was no warning message and his battery levels were OK.
The message you referred to is surprising.
I've never seen a critical power loss message and wonder how it would show if there was a critical power loss.
Perhaps the message was something else?
If you post your flight data, it might help understand the issue.
 
This is the flight record I downloaded off the iPad of the day she crashed
 

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  • DJIFlightRecord_2022-06-11_[17-11-37].txt
    33.2 KB · Views: 76
This is the flight record I downloaded off the iPad of the day she crashed
The message was Critically Low Power. Aircraft Landing. Throttle up to reduce the speed of descent and use sticks to avoid obstacles.
The cause was no mystery, and very different from the OP's issue.
The battery was dead.
It had been discharging before the flight and the % indication was false.
At start it shows as 70%, but at 5.3 seconds as soon as you tried to climb which put a load of 15 amps on the battery, the battery cells crashed to below critical low voltage (3.2 volts).

You can see the battery cell voltages here:
At 19.9 seconds (with cell voltages below 3.0 volts) there was another warning:
Critically Low Power. Aircraft Landing.
The drone fell from the sky when the cells were dead and unable to provide enough power to hold the drone in the air.
 
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Thanks for this analysis. So in other words, my batteries are history and need to be replaced? Probably not worth the effort?
 
Hi,

We recently had a crash with our P4P RTK where it appears to have suddenly lost power at the end of a mapping mission using Pilot. It finished its mission, triggered RTH, yawed to face its home point then lost power and dropped directly down landing on its landing gear which both snapped off and destroyed gimbal/camera.

Ive had a look at the logs and it had 10 "GPS mismatch error" during the first few waypoints, and the previous flight has 40 of the same error and at least 1 for the previous 8 flights. I know this can be indicative of nothing critical or potentially a compass / GPS / gyro mismatch. I wouldn't have thought this would cause it to suddenly lose all power like that though.

Compass cal was done approx a week before crash and flight area did not change. No significant metal in take off area but was iron ore rich environment. Battery log looks fine no dips in voltage or cell misbalance and had 28% at time of crash.

Any help diagnosing or how to diagnose the failure much appreciated. I have the txt and dat logs and will attempt to attach them to this thread.

Thanks!
If you can provide the P4P-RTK on board .DAT it will likely have some data about the abrupt power loss. That's the .DAT from the P4P-RTK itself not the .DAT that can be found on the mobile device. It will be large so you'll need to upload it to a public sharing site like DropBox or GoogleDrive and provide the link.
 
Hi,

We recently had a crash with our P4P RTK where it appears to have suddenly lost power at the end of a mapping mission using Pilot. It finished its mission, triggered RTH, yawed to face its home point then lost power and dropped directly down landing on its landing gear which both snapped off and destroyed gimbal/camera.

Ive had a look at the logs and it had 10 "GPS mismatch error" during the first few waypoints, and the previous flight has 40 of the same error and at least 1 for the previous 8 flights. I know this can be indicative of nothing critical or potentially a compass / GPS / gyro mismatch. I wouldn't have thought this would cause it to suddenly lose all power like that though.

Compass cal was done approx a week before crash and flight area did not change. No significant metal in take off area but was iron ore rich environment. Battery log looks fine no dips in voltage or cell misbalance and had 28% at time of crash.

Any help diagnosing or how to diagnose the failure much appreciated. I have the txt and dat logs and will attempt to attach them to this thread.

Thanks!
Were batteries fully charged and not left for a period of time. if left for a period they should be fully charged or they give false readings ie 70% power when there is none and it falls from the sky
 
Were batteries fully charged and not left for a period of time. if left for a period they should be fully charged or they give false readings ie 70% power when there is none and it falls from the sky
The battery cell voltages were well above critical low voltage levels at the end of the flight data.
See post #4
 

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