Inspire battery capacity rapidly drops in flight

[Shaun Stanton]

Disclaimer: I am not pursuing a discussion on the physics or reasons why a LiPo can fail. I am simply trying to get a sample of a very specific set of parameters to see if anyone else had experienced a similar rapid drop in battery life in flight.

Background: Two different Inspire 1's from two separate owners recently experienced an in flight drop from 55-54% to 4%. Each occurrence happened within a week from each other. Both pilots were able to safely land without incident. Each aircraft went into the auto land sequence at 4%

Both batteries have an average of 25 flight cycles. When the first one occurred, I immediately came to the conclusion that every other experienced pilot would infer. That it was just a bad lipo showing itself. But two batteries failing with almost identical parameters makes me want to investigate this further to see if something could be causing a false trigger. The smart battery supposedly uses an algorithm to alert the pilot on how much power is available due to certain parameters.

So what I am looking for is if anyone recently experienced a rapid drop in flight from around the 55% point to 4 or 5%.

I am not trying infer that there is an issue, or trying to cause alarm. Obviously 2 samples is not statistically significant, hence why I am trying to gather more data.

 

[kcsajtai]

Disclaimer: I am not pursuing a discussion on the physics or reasons why a LiPo can fail. I am simply trying to get a sample of a very specific set of parameters to see if anyone else had experienced a similar rapid drop in battery life in flight.

Background: Two different Inspire 1's from two separate owners recently experienced an in flight drop from 55-54% to 4%. Each occurrence happened within a week from each other. Both pilots were able to safely land without incident. Each aircraft went into the auto land sequence at 4%

Both batteries have an average of 25 flight cycles. When the first one occurred, I immediately came to the conclusion that every other experienced pilot would infer. That it was just a bad lipo showing itself. But two batteries failing with almost identical parameters makes me want to investigate this further to see if something could be causing a false trigger. The smart battery supposedly uses an algorithm to alert the pilot on how much power is available due to certain parameters.

So what I am looking for is if anyone recently experienced a rapid drop in flight from around the 55% point to 4 or 5%.

I am not trying infer that there is an issue, or trying to cause alarm. Obviously 2 samples is not statistically significant, hence why I am trying to gather more data.

Same thing happened to me, from 59% to 7% in seconds. I landed without any incident. I changed the battery and got back in the air immediately since I was on set, working. Next day I tried that battery again (after charging it of course), but there were no issues anymore. I used it many times since and this never happened again. I mostly plan a flight path to be able to do emergency landings any time so luckily it was not an issue, but good-bye over the water shots Which is kind of said for this amount of money. One more thing, which might be important: I was flying periodically. Imagine it like this: Turn on equipment, fly for like 60-90 seconds (around 10% of the battery), then land and turn it off. Wait for like half an hour then again. It was the fourth lift-off on that battery that day. It was an 8 day long shooting session and I did this routine every day, but this issue only occured once. Latest FW on everything. Battery (TB48) had 18 cycles in it at the time(3 weeks ago) if I remeber correctly. Now it's over 40.

 

[Benjamin Kenobi]

Hi mate,

Quite a common occurrence at the moment. It's not a bad lipo, just a software issue.

Are all the lipos software updated?

Had the lipos been left charged for more than 10 days?

And most importantly, were the lipos fully charged before the flight? For some reason Inspire lipos don't like being used with anything other than a full charge.

 

[Bartman]

For some reason Inspire lipos don't like being used with anything other than a full charge.

i don't have an Inspire but I read somewhere that to really get a full and reliable charge you have to discharge the packs before charging them or is that an old technique that doesn't apply anymore?

can someone please explain the philosophy behind "smart" batteries? my dumb batteries seem to work just fine but maybe i'm being a bit unsophisticated? boorish maybe even? lol

 

[Shaun Stanton]

Hi mate,

Quite a common occurrence at the moment. It's not a bad lipo, just a software issue.

Are all the lipos software updated?

Had the lipos been left charged for more than 10 days?

And most importantly, were the lipos fully charged before the flight? For some reason Inspire lipos don't like being used with anything other than a full charge.

I agree that it wasn't a bad battery. I knew that it had to be software issue just did not know which issue caused the trigger. The consensuses from here and other forums as well as other people with inspire is that it is related to the auto discharge function.

So I will tell the two said owners the reasons why this is happening, and keep it in mind for my own.

 

[Shaun Stanton]

i don't have an Inspire but I read somewhere that to really get a full and reliable charge you have to discharge the packs before charging them or is that an old technique that doesn't apply anymore?

can someone please explain the philosophy behind "smart" batteries? my dumb batteries seem to work just fine but maybe i'm being a bit unsophisticated? boorish maybe even? lol

You are correct in that the physics f the LiPo are still the same charging techniques still apply like discharge fully before recharge etc to expand its overall life.

The smart battery is DJI's answer to try to take the stupid out of people who don't understand C rates and how to set up Hyperion type Chargers etc. Unlike our traditional dumb batteries where we have to manually store them, the smart battery starts an auto discharge for you. Also unlike a normal lipo and telemetry down link where we see just see the voltage drop and have to know our selves how much time the copter has based off of pilot technique. The smart battery gives you a percentage readout that is normalized to the flying conditions to the aircraft under an algorithm.

Bottom line smart battery is attempting to take away the pilot type stuff like setting a bingo fuel, to make it more user friendly to the non pilot guy.

 

[Shaun Stanton]

Update: I just received some useful info from someone who is very privy with this issue. Apparently it is a firmware issue regarding the Automatic Discharge function for battery storage. As per normal operation after 10 days if the battery is not used it starts an internal sequence that to put your batteries into store state as per the DJI manual. If you do not run a battery down to zero before recharging it never really resets the sequence timer. The battery will always think it needs to be in store mode.

Steps to mitigate this problem:

1. If you fly a fully charged battery that could be in store mode:
a. If you land with 50 to 60 to reset a shot, do not shut the system off.
b. It is when the battery is in store mode and is shut off and turned back on it is telling the system that you are not flying a fully charged battery and will drop off aporx. 50% of the battery capacity. The circuit is trying to get the battery to reach 50% thats why you will only have the remainder of the capacity above 50 available at any time.
c. Starting with a fully charged battery and leaving the system on continuously until swapping out a new battery seems to alleviate this issue.

2. If you have not flown for 10 days or more you will need to discharge down to Below 5% and recharge.
a. That is the only way to reset the auto-store sequence.
b. This may or not be accurate #Proceed with caution#

This has been successfully reduplicated a couple times as well as to verify that not shutting off the system between takes mitigates it for now.

DJI is supposedly working on a fix in the future. So the above might be a work around. But as always tread with caution on anything involving batteries.

 

[jfro]

My 2 cents. Smart Inspire battery is flat dumb. It complicates and causes serious problems as well as undo stress. Doesn't do what it's supposed to and DJI has a big problem. I have 4 batteries and often am flying over water so this has been a huge concern for months since it was first reported. I'd say:
# 1. Pretty accurate ie, c. Starting with a fully charged battery and leaving the system on continuously until swapping out a new battery seems to alleviate this issue.

#2 Not so much. If you have not flown for 10 days or more you will need to discharge down to Zero and recharge.
Never heard this before and I've been reading lots of posts and opinions on the malfunctioning smart battery problem.

I've never experience the problem although I stress about it. I always fly full batteries but I do not recycle down to Zero unless I've flow the battery 10 or more times as advised. I've not seen anyone post about discharging down to zero if you haven't flown in 10 days. Not saying it's not true, but that's a new one to me and I've read tons and tons of posts. I probably will continue doing what I've done which is charge the day or day before I fly and start at 100%. Try not to fly, turn off battery and fly again. Big stress. Did that recently and was a bit nervous. Landed early. Last flight was over water so used freshly charged battery, even though the previous battery should have had enough juice for the flight.

Update: I just received some useful info from someone who is very privy with this issue. Apparently it is a firmware issue regarding the Automatic Discharge function for battery storage. As per normal operation after 10 days if the battery is not used it starts an internal sequence that to put your batteries into store state as per the DJI manual. If you do not run a battery down to zero before recharging it never really resets the sequence timer. The battery will always think it needs to be in store mode.

Steps to mitigate this problem:

1. If you fly a fully charged battery that could be in store mode:
a. If you land with 50 to 60 to reset a shot, do not shut the system off.
b. It is when the battery is in store mode and is shut off and turned back on it is telling the system that you are not flying a fully charged battery and will drop off aporx. 50% of the battery capacity. The circuit is trying to get the battery to reach 50% thats why you will only have the remainder of the capacity above 50 available at any time.
c. Starting with a fully charged battery and leaving the system on continuously until swapping out a new battery seems to alleviate this issue.

2. If you have not flown for 10 days or more you will need to discharge down to Zero and recharge.
a. That is the only way to reset the auto-store sequence.
b. Zero does not mean an unsafe depleted battery. Zero is the baseline above the safety threshold.

This has been successfully reduplicated a couple times as well as to verify that not shutting off the system between takes mitigates it for now.

DJI is supposedly working on a fix in the future. So the above might be a work around. But as always tread with caution on anything involving batteries.

 

[dazzab]

I was under the impression that the newest firmware addressed this issue. Guess not. I think one thing that may catch people out is that if you don't leave the update firmware file on the camera SD card for each battery that is used, then that battery's firmware will not update. So you may have updated the Inspire but not all your batteries. The notes for the firmware updated mention this although I'm quoting from my very poor memory.

 

[Shaun Stanton]

@jfro

I guess to be technically accurate run the battery to less then 5% or until the battery will no longer come on. That does necessarily mean Zero. They recommend running it down to near minimums.

If what you are doing works for you then I am not suggesting you change what makes you comfortable. I got info from someone who was in contact with DJI. He was able to reproduce the problem a couple times. And he found that the problem does not happen when the battery was discharged fully and recharged. He did find that the problem seems to only occur when the battery is being flown after the ten day mark. You and the other people who have not maybe correct. I don't know.

I see you have been doing this around the same time I have been doing it. You know how these things are. Stuff that doesn't make sense tends to be that. No one really has the reason why there used to be the fly away issue for instance.

I did not do these test myself. So I did caution those to take what I am saying with it a grain of salt and to maybe do trial test on their own. I am only providing info on a possible fix. Like everything on the internet if it does come from the OEM then of course chose to take any info with caution.

I have about 150 flights between the two aforementioned systems and never experienced this myself. Most of the time we have reset shots in fight keeping it airborne and only landed when we get to 25% mark and change batteries. I have been on set where we had landed and shut the system off mid battery and restarted is without incident. Most of the time these systems had been flying inside 10 day intervals as they get used quite often. It has only been recently that both systems were offline for more than 10 days or at least some of the batteries may have bee able to go past the 10 day mark.

I appreciate what you are saying, I just trying to point out information that was given to me from a very competent source.

I do agree with your sentiment about them being dumb batteries. Obviously DJI is trying to make these novice friendly. As a result they may have induced a problem. I do like that you can at least the individual cells voltage at least. There you can possibly spot a real bad battery before it happens.

 

[Shaun Stanton]

I was under the impression that the newest firmware addressed this issue. Guess not. I think one thing that may catch people out is that if you don't leave the update firmware file on the camera SD card for each battery that is used, then that battery's firmware will not update. So you may have updated the Inspire but not all your batteries. The notes for the firmware updated mention this although I'm quoting from my very poor memory.

That's good to know. I will bring that up to the two owners and see if that may be an issue. One owner seemed pretty certain that he updated all of the batteries. I will bring that to the gentleman who did the flight tests as well.

Confirmed one owner did confirm that he did indeed the newest firmware on all batteries per the DJI instructions.

 

[FerdinandK]

The only real parameter of interest of a LiPo is the Voltage under load. So DJI did not rely on the voltage (as is is a lot to explain, voltage can go down, can come up again, ...) and did the Battery using capacity and current measuring. But since they are aware of the problem there it is just that if the voltage drops during flight below (I think it is 3,5V a cell) the display changes immediately to 5% (and the resulting actions are taken). So if the batteries are not new, and have not been handled perfectly, they age, do the resistance raises, and if the a wind gust forces the copter to do a massive correction, the voltage can drop critically even if the capa should still be around 50%, so nothing new, nothing exceptional, just business as usual. Also I think people should be aware, that Phantoms and Inspires are flown much more on their limits as home-made copter are, I am flying my Phantom and my Inspire much closer to the limit as I am doing with my copter (with them I have mercy).

So open a support case with DJI,and or buy a new battery and the story is over, your expenses will still be much less in having a functional airborne camera than any other system.

best regards
Ferdinand

 

[Shaun Stanton]

The only real parameter of interest of a LiPo is the Voltage under load. So DJI did not rely on the voltage (as is is a lot to explain, voltage can go down, can come up again, ...) and did the Battery using capacity and current measuring. But since they are aware of the problem there it is just that if the voltage drops during flight below (I think it is 3,5V a cell) the display changes immediately to 5% (and the resulting actions are taken). So if the batteries are not new, and have not been handled perfectly, they age, do the resistance raises, and if the a wind gust forces the copter to do a massive correction, the voltage can drop critically even if the capa should still be around 50%, so nothing new, nothing exceptional, just business as usual. Also I think people should be aware, that Phantoms and Inspires are flown much more on their limits as home-made copter are, I am flying my Phantom and my Inspire much closer to the limit as I am doing with my copter (with them I have mercy).

So open a support case with DJI,and or buy a new battery and the story is over, your expenses will still be much less in having a functional airborne camera than any other system.

best regards
Ferdinand

I agree with you in the sense that yes voltages change under certain loads. I have, as many others that have been doing this for 4+ years know this as well. However, in my experience and seeing the experience of others I have never seen a rapid voltage drop after everything stabilizes under nominal conditions. Yes, if obviously flying a heavy load and you run and gun the throttle you will see a significant voltage sag. There are only two cases where I have seen the voltage drop excessively when flying in calm and stabilized flight conditions. Those were when the batteries experienced a terminal failure. When the above two situations occurred, both flights were flown under very mundane conditions. I have flown an Inspire 1 to its max limits and this issue never happened to me. So your assumptions are not valid in this case.

In this particular case it only happens when the system is shut off around the mid battery point and restarted. It does not occur when the battery is on continuously. My associate has tested this several times doing multiple flights to a reasonable statistic accuracy.

This is not your normal battery sag under load situation. I have looked for both system's data before I posted.

 

[jfro]

There is one certain fact IMO and that it is their smart battery software is buggy / flawed. I have flown my 20 lb x8 with 6s batteries and never experienced s rapid voltage drop like what is happening to users. I am constantly flying & testing my many gimbals in R&d mode on partial batteries. Never an issue. The inspire battery system is flawed. Only fly on full batteries until this gets fixed. Guess if it's out side 10 days, 2 be safe, maybe do a full recycle....

 

[SleepyC]

Anyone have a method to run a battery down (safely) without flying them?
I charged a bunch up for a shoot and the weather turned, It's been days of 50 mph winds, no chance tofly.
I used to use light bulbs and resistors, but have no idea how they would apply to the smart batt.

Anyone have a way to bring them down?

 

[Bartman]

it sounds like the smart batteries self-discharge after ten days of non-use

 

[SleepyC]

it sounds like the smart batteries self-discharge after ten days of non-use

Right but if you NOW want to fly to turn off the "smart discharge" after a FEW days you have to take the battery to 5%, and then charge full.
So how are people discharging their packs to 5% so they can then fully charge them.

 

[kcsajtai]

Right but if you NOW want to fly to turn off the "smart discharge" after a FEW days you have to take the battery to 5%, and then charge full.
So how are people discharging their packs to 5% so they can then fully charge them.

From the DJI FAQ:
Slow: Place the Intelligent Flight Battery into the Inspire 1 battery compartment and turn it on. Leave it on until less than 8% power remains, or until the battery can no longer be turned on. Launch the DJI GO app to check battery levels.
Rapid: Fly the Inspire 1 outdoors until less than 40% of the battery’s capacity remains.

Not very sophisticated but i guess it works...

 

[SleepyC]

Yea I read that but if you can't fly due to weather and you have 7 batteries to condition, there is no way you can just leave the I1 on! It takes like 5 hours per pack to drain them just sitting there! There has to be a better way. Like a resistor, a light bulb or something!

 

[kcsajtai]

Yea I read that but if you can't fly due to weather and you have 7 batteries to condition, there is no way you can just leave the I1 on! It takes like 5 hours per pack to drain them just sitting there! There has to be a better way. Like a resistor, a light bulb or something!

Well, by not very sophisticated, I meant it's a good for nothing, would be better if it wasn't there in the first place, typical DJI solution, for a problem, that isn't really a problem. Which one would you want to save? A battery or the whole aircraft? I' would be happier with only a dead battery, than with a lost aircaraft underwater (including the battery ). To be on topic, I've searched a bit, but found exactly nothing. Maybe wiring the battery up to a standard lipo charger with storage function could help, but who knows.