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Fell Out of Sky - Total Loss
- Thread starter tcope
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Wow. It's impossible to read that review and not add the product to your cart. Thank-you
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Sorry bro! We didnt have a prob til then right! But know its always be on yer mind. (Or not)
I think there is more to be investigated here. I'm an engineer - electrical engineer by education, and "smart batteries" are usually not too smart. Early indications seem to indicate state of charge for LIPOs are very hard to determine accurately. I think there is an issue based on lots of crashes and little explanation - other than flight logs where voltages drop below levels that cannot run the electronics in the P3 and Inspire.
This is a forensic evidence analysis exercise. Who in this forum is a reverse engineering expert or forensic re-assembler? Other engineers, etc. are welcome to crowd-source this with us. Let's solve it and provide a recommended fix to DJI if it really is a flaw as it seems.
I am not an engineer, but I have been using LIPO batteries for a long time.
I wonder if it is possible for HealthyDrones to determine acceleration/ increase in load? A battery which is not fully charged will show quite a large voltage drop (relatively speaking) when put under a sudden heavy load, such as a max speed ascent. If the 'intelligence' misinterprets that drop, how will it react?
Today I used a battery in autodischarge (60%) and P3A flight fine and no shutdown, until 35%, when I land the bird.
It's a well known engeneering problem how to sample cells voltage. When lipo charge fall down to 45-50% (< V3.70 x cell) they start loosing linearity. This is due to high juice needed by the motors ( they require a peak of 14A = 14.000mA) the voltage for sure drop seriously and not all the cells respond in the same way. For example if motors are idle on the ground and you take off with full forward stick, you will note a big voltage drop down. The intelligent battery firmware has probably a flat response to this event and if it senses <3.20V just shutdown battery (for safety?)... this means in-flight power cutoff.
When using a not-fully charged battery, it's NOT raccomanded anyway that this is at <60%-55% charge. (DJI NOT raccomand anyway..)
It's a well known engeneering problem how to sample cells voltage. When lipo charge fall down to 45-50% (< V3.70 x cell) they start loosing linearity. This is due to high juice needed by the motors ( they require a peak of 14A = 14.000mA) the voltage for sure drop seriously and not all the cells respond in the same way. For example if motors are idle on the ground and you take off with full forward stick, you will note a big voltage drop down. The intelligent battery firmware has probably a flat response to this event and if it senses <3.20V just shutdown battery (for safety?)... this means in-flight power cutoff.
When using a not-fully charged battery, it's NOT raccomanded anyway that this is at <60%-55% charge. (DJI NOT raccomand anyway..)
I forgot to mention that battery have different behaviour (linearity) depending also on the temperature. Using the same partially discharged battery SOON AFTER a flight, will rise the probability of a serious voltage drop-down due to higher temp of the lipo substrate !
I land a few times every mission, because of the altotid is takeoemn from the takeoff position so I got -2m altitude in some point
Flying below actual takeoff point, shouldn't be a problem, for you.
Many here fly off the top of mountains, down to the valley floor and back up again, without remorse. As long as the battery is warm, you should be good to go.
I wouldn't take off with a low charge battery. If it had been cooled off already.
RedHotPoker
Many here fly off the top of mountains, down to the valley floor and back up again, without remorse. As long as the battery is warm, you should be good to go.
I wouldn't take off with a low charge battery. If it had been cooled off already.
RedHotPoker
So it seems that DJI has admitted it is a firmware issue. The battery is so smart it is shutting down (irony here) ! See this link and where it leads.
DJI may replace your P2, Inspire, or P3 if it crashed due to battery | DJI Phantom Forum
It should not and I see no indication that this is an issue. I've flown hundreds of times like this and thousands of other people have as well. Charge the battery up and if it down to 30% or 20%. But I recommend that you don't fly with a battery that has auto discharged without charging it up fully before. It's also always a good idea to only start flying with a battery that is at 100% but you should be okay with one that is lower.
What I also _highly_ recommend is that you go into settings, the battery icon and turn on the setting to display the voltage of the battery next to the percent left. It should stay around 3.8v until you start to get low. It will then drop to 3.5v and you are getting low. At 3.3v you should consider landing (I think these amounts are correct).
Likely battery not fully snapped in, defective battery or a battery connection issue. Been there, done that, but with a P2V (not-plus, but basically the same bird). Battery charge data screen should give a clue.
This thread seems to be mostly about batteries. Reading through this thread and other threads like it, it seems the risk of "drop from the sky" is not necessarily from using a battery that isn't fully charged, but rather the risk seems to be mostly in using a battery that has entered the discharge state and then not fully charging it before use. And this problem may be exasperated by P3 owners who change their discharge time down to a day or two. This is a lot less than P2V batteries that have a default of 10 days before beginning discharge.
The following comments are my understanding of LiPos in general, and if somebody thinks I'm mistaken, don't hesitate to correct me.
My understanding is that LiPo cells are basically the same as far as voltage. They all have a "nominal" charge of 3.7 volts. Hence, the toy drones that use a single cell LiPo hold a nominal charge of 3.7 volts.
The three cell LiPos (3S) that the P2V and P2V+ uses holds a nominal charge of 11.1 volts. Makes perfect sense, right? Because 3.7 multiplied by 3 equals 11.1.
However, what throws me a little is that the P3 battery specs show a charge of 15.2 volts. And since it has four cells (4S), that breaks down to 3.8 volts per cell, not 3.7 volts per cell. Can somebody explain why the specs show an extra .1 volt per cell?
We all know that the batteries at full charge all actually will hold MORE voltage than what is stated in the specs. So is there a definition for the word "nominal?" In other words, why are P2V batteries listed at 11.1 volts when we know they hold over 12 volts fully charged?
Finally, let me mention my discharger. I got it on eBay and it is supposed to work for all LiPo batteries from 3S-6S. Hence, it would work for a P2V battery and a P3 battery. It's designed to bring a battery down to 3.85 volts per cell for storage purposes. And then if you want to do a DEEP discharge, you can push the little button on the discharger and it will take it down further to 3.5 volts per cell. Then it will shut off.
The last battery I did that, I checked it with my Vision app, and the cells showed about 3.5 volts each while the current charge was indicated at 3%.
But this was my Vision battery. Are P3s different? Can P3 batteries fly around with 3.5 volts safely? I would think it would be time for some kind of emergency landing at that point.
The following comments are my understanding of LiPos in general, and if somebody thinks I'm mistaken, don't hesitate to correct me.
My understanding is that LiPo cells are basically the same as far as voltage. They all have a "nominal" charge of 3.7 volts. Hence, the toy drones that use a single cell LiPo hold a nominal charge of 3.7 volts.
The three cell LiPos (3S) that the P2V and P2V+ uses holds a nominal charge of 11.1 volts. Makes perfect sense, right? Because 3.7 multiplied by 3 equals 11.1.
However, what throws me a little is that the P3 battery specs show a charge of 15.2 volts. And since it has four cells (4S), that breaks down to 3.8 volts per cell, not 3.7 volts per cell. Can somebody explain why the specs show an extra .1 volt per cell?
We all know that the batteries at full charge all actually will hold MORE voltage than what is stated in the specs. So is there a definition for the word "nominal?" In other words, why are P2V batteries listed at 11.1 volts when we know they hold over 12 volts fully charged?
Finally, let me mention my discharger. I got it on eBay and it is supposed to work for all LiPo batteries from 3S-6S. Hence, it would work for a P2V battery and a P3 battery. It's designed to bring a battery down to 3.85 volts per cell for storage purposes. And then if you want to do a DEEP discharge, you can push the little button on the discharger and it will take it down further to 3.5 volts per cell. Then it will shut off.
The last battery I did that, I checked it with my Vision app, and the cells showed about 3.5 volts each while the current charge was indicated at 3%.
But this was my Vision battery. Are P3s different? Can P3 batteries fly around with 3.5 volts safely? I would think it would be time for some kind of emergency landing at that point.
@markmnd nominal cell voltage is 3.7 but on the market you can find new Lipo chemical that raise new nominal v to 3.8. I don't know dji what's using in p3 battery.
Deep cell discharge is at 3.2v, not raccomanded to reach. When you use an external discharger mostly you use a so called dummy load. The p3 battery has it's own controller and not exposes cells outside. So battery shutdown based on firmware behavior, not on discharger control.
P3 battery has a conservative firmware that close juice when cells have too much fluctuations on single cells.
Deep cell discharge is at 3.2v, not raccomanded to reach. When you use an external discharger mostly you use a so called dummy load. The p3 battery has it's own controller and not exposes cells outside. So battery shutdown based on firmware behavior, not on discharger control.
P3 battery has a conservative firmware that close juice when cells have too much fluctuations on single cells.
60% battery shouldn't cause a drop off, If that is the case, the low battery warning should be set at 99%.You will realize when your panty drops off in the open
Back to the point: there are chances that some one misses a check sometimes and the penalty should not be that heavy if our dear software engineers can plug few auto checks. This is my point and not a baby sitting. We are talking about a professional product and not something designed in a corner of a lab.
