Finally lost my bird after 9 months of great no issues flying.

[niterider]

Great! Tks sini & waba!

 

[Waba waba]

Comparing those .csv has been very interesting....the charge in capacity determined by the Phantom and my calculations by doing current integration agrees, but seems to indicate that you only had 36% battery at the start of your first flight. The voltages under load show it was less than 100%, although the data shows it near 100%, but not that low. The voltage decay does not match my example flights, it seems to stay flat. Also, on my example flight voltage and percentage correlate with a R^2 of near .9 and yours is less than .01. How may charges did you have on that battery? Do you have any idea what the cell difference is between cells? That would be in the .dat files if you feel like retrieving them. It looks like the battery life was at 85%....puzzling....

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[TheRealNick]

Was that your first flight?

Here's a plot of your voltage versus flight time in seconds also showing a typical flight I pulled. As shown, the initial voltage drop was higher than normal and it stayed kind of flat with some large dips. When you started the second flight the voltage started higher than were you ended it as expected, but it dropped down rapidly....

 

[Waba waba]

Was that your first flight?

Here's a plot of your voltage versus flight time in seconds also showing a typical flight I pulled. As shown, the initial voltage drop was higher than normal and it stayed kind of flat with some large dips. When you started the second flight the voltage started higher than were you ended it as expected, but it dropped down rapidly....

View attachment 42971

No that was the second flight ..these are the first flight

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[Waba waba]

Cell 4 looks like the culprit.. But still don't think it should have dropped like how it did.


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[Phantom751874]

Quick 2 questions on cycling batteries: I have three batteries; 18,19,22 times charged. Sounds like its time i refresh all of them. What is the process to bring down to 0% and rebuild to 100%? Generally i end all my flights at about 40% battery remaining for safety. Does this create a memory within the battery that is bad?

I charge to 100% then fly until maybe 15% then land, keep in close to you at 30% and let it go to 15% or even 10% then land and turn her off. At that point I take her props off and start her up at home and I personally go down to 2% then turn off the P3. Let everything cool down then charge up to 100%. Then fly to 50% and done (storage).

I used to go down to 8% but another member her I respect said it looks like the re-calibration was changed to trigger at 2%. I have no proof but that's what I did and no harm done.

 

[Phantom751874]

Cell 4 looks like the culprit.. But still don't think it should have dropped like how it did.


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1 minor deviation isn't going to do it, guidance has been more than 10 and if from the same cell them keep an eye on that battery. I have minor intermittent deviations off and on in all my batteries and no issues yet.

 

[gmartinez0003]

Perhaps you're right, but if it were me I would still be expecting the P3 to make it home in that situation.

View attachment 42912

HealthyDrones.com - Innovative flight data analysis that matters

Hey Oso, I haven't had any problems with any four of my batteries, but it's always in the back of my mind. I use RC Remote button 'C1' for battery info and 'C2' for satellite to video swap for quick access without going to iPad. But I really don't know what I'm looking for besides green, yellow,and red cell changes. Can you tell me what are some abnormal readings on individual cell voltage or other signs I could noticed of an accident waiting to happen? I'm just going to make some numbers up, In example - if first cell is 3.57 and other cells read the same at say 3.63, is this normal or what's the differential that is something to be concerned about.


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[TheRealNick]

Hey Oso, I haven't had any problems with any four of my batteries, but it's always in the back of my mind. I use RC Remote button 'C1' for battery info and 'C2' for satellite to video swap for quick access without going to iPad. But I really don't know what I'm looking for besides green, yellow,and red cell changes. Can you tell me what are some abnormal readings on individual cell voltage or other signs I could noticed of an accident waiting to happen? I'm just going to make some numbers up, In example - if first cell is 3.57 and other cells read the same at say 3.63, is this normal or what's the differential that is something to be concerned about.


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Need to look at the whole flight, but when lowest cell is 3.6 you should land. Check the deviation from full charge to lowest cell at 3.6, it should be small at full charge....

 

[John Locke]

At that point I take her props off and start her up at home and I personally go down to 2% then turn off the P3.

I used to go down to 8% but another member her I respect said it looks like the re-calibration was changed to trigger at 2%. I have no proof but that's what I did and no harm done.

Can you elaborate? Are you following someone's suggestion to discharge to 2% without statistical proof, just because you respect him? Is he a battery engineer?

It seems odd that the recalibration trigger would suddenly go down to 2%.

Did you notice your 4 cells equalizing more evenly than using 8% on other batteries?

How do you know that no harm was done until you see how much longer the battery lasts?

 

[TheRealNick]

You can check on the various EV vehicles, none of them take the battery that low...that is for battery life. I can see a reason maybe if you have a problem, but I am skeptical it would help. I land about 30% and don't discharge further....

 

[Drone Wolf 69]

What are the effects of not performing a deep discharge after 20 charges. Could this battery have been effected in a manor such as this. I never pay much attention to "Battery Percentage",..but I do to the "Weakest Cell Amps". From all I've read on this forum & others,.is that your battery is only good as your weakest cell. If my weakest cell is @ 3.6 amps it's time to bring her in regardless of what my battery percentage is & I will not let it get to far or high,.knowing it's going to approach this point soon. Seems like a lot of birds dropping out of the sky,.do to pilot error of watching battery percentage,.rather than weakest cell amps. Would not deep discharging a battery after 20 charges cause this type of scenario?

 

[Mark The Droner]

My understanding is, the primary reason you want to do a deep discharge is to calibrate the battery reading. In other words, if you don't do it, you may be misled regarding the percentage of charge. However, some veteran Phantom owners may tell you a deep discharge is not necessary.

 

[DB4Tim]

I'm going to make this short.. Flight log is attached..

At 56% left. Low voltage warning. Going to land. Looked at app.. No signal. Looked up bird is gone. Went for a swim. It was the second flight on the battery for the day, I live in Miami where temp is not an issue. Plus I have over 45 hours of flying the phantom and never had issues and pretty experienced with it.. Now what should I do. Besides fish it out.. Also I was on 1.4 firmware. I was no where close it have sticks to center if yall thinking about it too

What program do you usr to open your flight data

 

[DB4Tim]

One that novices could use and understand...like me

Exactly right & why testing a car battery you apply 50-100 amp load & measure the voltage drop. We need an enterprising company to develop a compact load tester for P2/P3 packs.

 

[Waba waba]

What program do you usr to open your flight data

I used iTunes to download the files from dji app. Then upload them to Healthydrones.com


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[Case29247]

Voltage is misleading. What powers the motors is current. You could show 100% charge (voltage)....and not have enough current to sustain flight. That's my opinion on why sometimes folks have crashes moments after takeoff among other reasons.
Personally, I don't trust voltage readings without doing a true load test on my batteries periodically.

Also, it is not unheard of for solder connections on batteries and connectors to fail. They are often soldered. If you fly until your battery is depleted and continue to demand current from the battery, the heat rises from the resistance and can soften solder. That's why you should always use Hi-Temp solder when making high current battery connections such as the Phantom.

Actually, OUTPUT POWER (which is what keeps the bird flying) of the motors is a function of the INPUT POWER, which is somehow a function of BOTH voltage and amperage. In a simple system, this is simply the product E x I. However, for motors (these motors or any motor), the power you put in versus the power you get out is more complicated than simply E x I.

And then the limitations and operational dynamics of the batteries makes it even more complicated. The limited and complex ability of the batteries to deliver the necessary voltage and current to the motors varies dramatically over temperature and state of charge.

It's pretty easy for me to imagine how the performance trajectories of both the motors and the batteries can easily find them on a collision course where the batteries cannot deliver both the power (voltage and current) that the motors require, and the motors basically break down and cannot deliver the power for flight. In many types of motor designs, this breakdown can be very sudden. One second it's humming along merrily, and the next second it's humming and smoking. (Your typical induction motor, for instance)

Possibly the best advice would take the form of, "Fly conservatively, especially with cold or very hot batteries (both excessive cold and heat will limit current for different reasons), and/or with partially discharged batteries." Maybe we should add, "Also with very warm motors."

But IMO the key for safe flight is, "fly conservatively."

 

[JKDSensei]

D-a-n-g !
I been schooled by a cowboy toddler
Thanks young man!

 

[TheRealNick]

Actually, OUTPUT POWER (which is what keeps the bird flying) of the motors is a function of the INPUT POWER, which is somehow a function of BOTH voltage and amperage. In a simple system, this is simply the product E x I. However, for motors (these motors or any motor), the power you put in versus the power you get out is more complicated than simply E x I.

And then the limitations and operational dynamics of the batteries makes it even more complicated. The limited and complex ability of the batteries to deliver the necessary voltage and current to the motors varies dramatically over temperature and state of charge.

It's pretty easy for me to imagine how the performance trajectories of both the motors and the batteries can easily find them on a collision course where the batteries cannot deliver both the power (voltage and current) that the motors require, and the motors basically break down and cannot deliver the power for flight. In many types of motor designs, this breakdown can be very sudden. One second it's humming along merrily, and the next second it's humming and smoking. (Your typical induction motor, for instance)

Possibly the best advice would take the form of, "Fly conservatively, especially with cold or very hot batteries (both excessive cold and heat will limit current for different reasons), and/or with partially discharged batteries." Maybe we should add, "Also with very warm motors."

But IMO the key for safe flight is, "fly conservatively."

Power from the battery is as simple as current times voltage in wattage, agree for motors it is more complicated....

There is not real mystery to these crashes, they usually start with battery around 15.5 which quickly drops to below 14.4 and then quickly to 12 V. and then everything shuts down around 12 V, perhaps when any single cell drops below 3V. The mystery to me is what is causing the battery percentage to be off. Flying on a previously used battery seems to be a factor, but so far I have not been able to recreate it...

 

[timmydjr]

Unfortunately the problem is when you run a pack down half way, then turn it back on & fly with the now cold pack, the results can quickly become catastrophic.

Assume you normally land at 25-30%. You lifted off at 67%. Factoring in voltage recovery, your pack was likely down to nearly 50% on the first flight. In only 2 minutes the voltage dropped to the point of shutdown. This situation is exacerbated by the power demands of a quick liftoff & countering a 17 mph wind.

For the sake of safety & the aircraft it's preferable to lift off with a fully-charged battery. I always show up to fly with 4-8 freshly-charged packs & fly them to completion. As you can see this is a good practice to follow. I am sorry for your loss & hope you are able to recover & salvage your Phantom.

Thanks for the post. I have had my P3 for a month or so and have had no issues. Got my dad one for Christmas and 12 days later, he did have a failure of some sort but not sure on the details. Did not matter as the damage was done.

I am sure I can google for info but I am looking for good solid info from a reliable source (which you seem to be). I have 4 batteries. I am trying to run them down to below 10% by just flying right around very low and close for the last little bit.
1. What is the best practice for battery management? Should I immediately recharge them if they are below 10% or just wait until the day before I am going to fly again?
2. I am unclear on the "refreshing". Should this be done every so many cycles or is there a specific test to know when?
3. When batteries are brand new, should they be only drained to a certain point (ie 50%) or should I just drain them to under 10% always?
4. Last one. If for any reason I have to quit early and my battery is at, say 50%. Would it be better to just recharge it or would it be better to fly on it again later (right in my front yard) (ie work on manuvers in my front yard, to run it down below 10%).

Thank you again for your post and I hope you can help me with these battery questions. I am sure there are other newbs like me that just don't know all the facts on best battery practices. My neighbor just gone one too so I want to pass on the details to him as well.