To get an ideal of how abnormal this looks I would take a look at a fully charged battery and compare its voltage from 15.1V with a similar load of about 14A, i.e. determine how long it takes to drop below 14V. To make a proper State of Charge ("SOC") map you need voltage and current and the output is SOC (taking from test data, and then you need to account for battery degradation over time). You also need a current draw that is high enough to pull the voltage down to reflect the SOC. This is not a trivial task; however tracking the SOC from a fully charged battery is easy to do.
P3P - Loss of Power and Crash
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I've successfully used a voltage monitor on my P1 and F550 and turned off the DJI battery monitor on those systems.
I'm talking about a failsafe voltage monitoring system and not so much the intelligent side of it.
If there was an actual alarm monitoring the voltage, it would be better than finding out your voltage is low when you're up and away.
In the .DAT the remaining capacity is a 1 Hz signal. Same for all the other battery data.
It's a great idea to keep the voltage reading on the main screen during flights . Ascending full throttle uses a ton of voltage so much that a battery with less than 75% charge can't handle it. Just my opinion. If you are taking off with less than a full battery you'd better he easy on the sticks or there's a good chance your bird will fall out of the sky. Good luck and stay safe !!
alokbhargava
Premium Pilot
I disagree.
It's not voltage, it's energy that's used to lift. Can't believe we need 75% stored charge if we accelerate fast.
My P3S crashed from 9m height onto concrete yesterday - sudden power cut mid-air. The drone was only about 10m away from me. (screenshot attached)
Prior to flight the battery was 100% charged.
At the Point of the power cut the drone had just gone into automatic landing due to low battery, but there was still 1:51min worth of battery left. It was the maiden flight.
Any idea why this could have happened? Is it likely that the drone was faulty Prior to the Crash?
Prior to flight the battery was 100% charged.
At the Point of the power cut the drone had just gone into automatic landing due to low battery, but there was still 1:51min worth of battery left. It was the maiden flight.
Any idea why this could have happened? Is it likely that the drone was faulty Prior to the Crash?
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Bad batteries are quite rare, at least if we´re talking above a certain price/quality level of course. During my LiPo RC days prior to DJI I´ve seen lots of problems going on, but 2 situations were the most common:
1. If a battery is defective or discharged, the bird simply wouldn´t take off. That happened often and still do, we are always experimenting with batteries and systems, all the time. I´ve heard about it but to be honest I personaly don´t remember seeing a plane or copter going down mid-flight like these Phantoms, certainly not one of mine and certainly not at this scale.
2. Most of the times, we found that something on the bird´s systems was causing the batteries to malfunction in some way. A short circuit, a bad component, something. Either that or the battery was done, dead, or just plain discharged. Even "ready, closed and complete" aircrafts in the style of Phantom and Inspire demanded tweaks and experimentation, but most MRs were built from parts or kits so everything had to be tested before the first flight.
We´d check voltage and/or try the same battery on another device, like a RC car or something, and it´d either work fine (indicating the bird has an issue) or not at all (the battery was kaput or discharged). Also, problematic batteries usually won´t charge at first. We´d try and try and they wouldn´t hold a charge for some reason, bad cells or whatever, at least not enough to even take off.
The rules have always been the same: only use quality batteries (which DJI´s are); always check charge before flight; always use caution and stay on the conservative side, that is don´t push your batteries or test limits; don´t ever fly with erratic batteries or ones that behaved bad or weird before; always follow the capacity and charge/discharge recomendations; always have spares... and so on.
All that has been estabilished through a lot of trial and error. One problem I (my opinion) see with the Phantom is that it comes so "ready" and with lots of flight protection systems and all that many users without any previous experience or knowledge about LiPos, MRs and this stuff simply take for granted it will just fly, every time. Just plug and play, it´s certainly designed with that in mind and promoted by DJI that way.
And most of the time I´d guess it just flyes a lot without problems. Mine does, with all 3 different batteries even when I do 3 or 4 flights from a single charge in the same battery. But if something goes wrong - and it always will - accidents like these are alsmot innevitable.
1. If a battery is defective or discharged, the bird simply wouldn´t take off. That happened often and still do, we are always experimenting with batteries and systems, all the time. I´ve heard about it but to be honest I personaly don´t remember seeing a plane or copter going down mid-flight like these Phantoms, certainly not one of mine and certainly not at this scale.
2. Most of the times, we found that something on the bird´s systems was causing the batteries to malfunction in some way. A short circuit, a bad component, something. Either that or the battery was done, dead, or just plain discharged. Even "ready, closed and complete" aircrafts in the style of Phantom and Inspire demanded tweaks and experimentation, but most MRs were built from parts or kits so everything had to be tested before the first flight.
We´d check voltage and/or try the same battery on another device, like a RC car or something, and it´d either work fine (indicating the bird has an issue) or not at all (the battery was kaput or discharged). Also, problematic batteries usually won´t charge at first. We´d try and try and they wouldn´t hold a charge for some reason, bad cells or whatever, at least not enough to even take off.
The rules have always been the same: only use quality batteries (which DJI´s are); always check charge before flight; always use caution and stay on the conservative side, that is don´t push your batteries or test limits; don´t ever fly with erratic batteries or ones that behaved bad or weird before; always follow the capacity and charge/discharge recomendations; always have spares... and so on.
All that has been estabilished through a lot of trial and error. One problem I (my opinion) see with the Phantom is that it comes so "ready" and with lots of flight protection systems and all that many users without any previous experience or knowledge about LiPos, MRs and this stuff simply take for granted it will just fly, every time. Just plug and play, it´s certainly designed with that in mind and promoted by DJI that way.
And most of the time I´d guess it just flyes a lot without problems. Mine does, with all 3 different batteries even when I do 3 or 4 flights from a single charge in the same battery. But if something goes wrong - and it always will - accidents like these are alsmot innevitable.
Thank you gentlemen for your posting of the data results.
Looking at the battery voltage shows what more than likely happened. Voltage dropped to below required level thus shutting down the system.
While I do not like the outcome I have learned from it.
Still waiting on DJI to respond and I have ordered spare parts to repair it myself if needed.
Looking at the battery voltage shows what more than likely happened. Voltage dropped to below required level thus shutting down the system.
While I do not like the outcome I have learned from it.
Still waiting on DJI to respond and I have ordered spare parts to repair it myself if needed.
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Hi, am I missing something here? Your battery was 100% charged but only had 1.50 minutes left after a few seconds flight? Just trying to understand.....
There is a discussion at the DJI forum. It seems that the Inspire is having the same issue. Some users have been able to document the bug as a firmware problem where the bird is shut off when it has in fact plenty of juice left to land.
DJI Forum|The head-scratcher's battery tests and thoughts.
DJI Forum|The head-scratcher's battery tests and thoughts.
what program is it you use to show the log file? i only can se in excel and thats a lot of numbers and other information in that, your program look much simplyar
Just tried the phantom safe landing procedure on the next charge only just above ground. Worked fine, even a second time after it had done one safe landing.
Tried to read out the flight log from the phantom to try and find out what happened on the crash, but did not manage to get the SD card in the plane to mount on my mac. doh!
Tried to read out the flight log from the phantom to try and find out what happened on the crash, but did not manage to get the SD card in the plane to mount on my mac. doh!
The P3 flight log is on an internal SD card; it's not the camera SD card. Instructions for retrieving that file can be found by going to FLYXXX.DAT and then press the "Retrieve .DAT file" button at the top. It'd be good if you could DropBox that .DAT so that we can take a look. If you can't DropBox it then upload it to FLYXXX.DAT and I'll retrieve it and DropBox it.
Thanks for the pointer. I am aware its on the SD card of the camera. I saw the image "DJI FLY LOG" in disk utility, but I could not mount the drive. I will give it another go.
The program is Dashware - should have a profile for it soon so you can view the DAT logs.
These batteries are not "smart" and the information they give is misleading. I always have charged my batteries on the day of flying, and now after seeing this, will make that my standard practice!
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This isnt only happening to flights with day old batteries though, while there are plenty of those reports, this happened to my bird & others w/ freshly charged 100% bat w/ the relation being its happening a few seconds into the flight
I have just found another piece of information on my flight that ended in the crash: the voltage of cell 1 dropped below 3V which caused the pack to shut down, see screenshot attached.
Subsequent flights showed bad battery health too.
The crash clearly was cause by a brand new duff battery, what are my chances of getting my slightly damaged phantom replaced (including the battery)?
Subsequent flights showed bad battery health too.
The crash clearly was cause by a brand new duff battery, what are my chances of getting my slightly damaged phantom replaced (including the battery)?
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