Battery-killing firmware bug?

[tfmkevin]

Has anyone else experienced batteries destroyed by the firmware bug that was supposedly fixed in the latest release?​

"Major Updates
1. Improved encryption to enhance transmission security. Aircraft and Remote Controller must be upgraded to prevent unlinking.
2. Fixed issue of batteries over-discharging when stored for extended periods of time (over 90 days)."​

I saw that in the release notes and became worried as my batteries had been stored since last fall when I updated to the latest (at the time) firmware.

When I got my batteries out, sure enough, both my TB47s were completely dead.

First DJI asked me to send a video showing the problem. Yes. A video. Of completely dead batteries.

Ok. Sure.

Then DJI support said:

We'd like to ensure that your battery is communicating properly with the unit. We would recommend that you attempt to refresh the latest available firmware update for the battery. The firmware can be found on the DJI Website.
http://www.dji.com
Please be aware that the information provided indicates that the batteries are outside of their warranty period. If the issue does require you to send the battery in for repair, it would not qualify for a warranty replacement. To review the warranty period for all parts related to our products, please review the After-Sales Service Policy, located at the following link:
​

I explained that it was not the batteries that were defective, but the DJI firmware which I was forced to install after the battery warranty had expired. The firmware had caused the batteries to over-discharge during storage, thus destroying them. And, because they were still completely dead, I could not "refresh the latest firmware update."

DJI then replied:

"Thank you for your response. As your batteries are out of warranty, it would require for you to purchase new batteries. Please click on this link to learn more on this point:"
​

So, basically, DJI required me to install firmware which had a bug that destroyed all my batteries. Then, they told me to go buy new ones.

Anybody else experience this?

 

[damoncooper]

Put them on charge and leave em for an hour or so to see if they don't revive.

I've heard of one such case where this worked

 

[Scotflieger]

Why do you think it is the firmware that is to blame? Leaving batteries for such a long time in store is never a great idea. What percentage did you discharge them to before sorting them? The recommended is 50%.

 

[damoncooper]

Why do you think it is the firmware that is to blame? Leaving batteries for such a long time in store is never a great idea. What percentage did you discharge them to before sorting them? The recommended is 50%.

I suppose it could have been aliens, but I'd say that assuming nothing strange was done to these batteries, the evidence points to the firmware bug. Encountered it myself, although I caught mine before they got tithe point where they wouldn't turn on.

 

[Mad_angler1]

If your capable pop the top off the pack and take a reading of the pack voltage with a multimeter directly would be a good start, this may just be the fw has entered deep sleep and won't wake up, this can be resolved by disconnecting the internal connector for a few hours BUT we need to know the pack voltage first otherwise doing this will still allow you to charge the pack but if the cells have been completely discharged you could potentially get fire or complete failure in flight.

We need to know the voltage of the pack then possibly cells to start with.

 

[tfmkevin]

I'm an electronic engineer. I did already take the top off, measure the cell voltage (less than 1V), attempt the "unplug the balancing plug" reset trick, and even some direct charge to the cells to see if they would resuscitate. They are definitely dead.

One of the "smart" features of these batteries is that they auto-discharge to storage voltage if unused for over 10 days. The firmware bug apparently causes them to keep discharging far below storage voltage if left a long time (3 months or so), thus destroying them.

I am confident this is what happened to my batteries. They had each been flown six times, then stored for about five months. Then they were charged and the firmware was updated. Then they were stored for the final fatal four months with the buggy firmware installed. Now they are most certainly destroyed.

DJI clearly acknowledges the bug and says it was fixed in the latest release. It's in the release notes. But they take no responsibility for the batteries it destroyed, even though the firmware update was mandatory.

Interestingly, it is probably almost impossible for a battery destroyed by this bug to ever still be in warranty, because it takes almost as long as the warranty period for the bug to destroy a battery. And, it's not the battery that is defective in the first place, it is a firmware update that was applied much later. There is perhaps no warranty on firmware or any damage it causes, despite it being mandatory?

 

[damoncooper]

At the risk of sounding like a nanny, did you try putting them on charge with the DJI-supplied charger for an hour?

 

[Scotflieger]

I'm an electronic engineer. I did already take the top off, measure the cell voltage (less than 1V), attempt the "unplug the balancing plug" reset trick, and even some direct charge to the cells to see if they would resuscitate. They are definitely dead.

One of the "smart" features of these batteries is that they auto-discharge to storage voltage if unused for over 10 days. The firmware bug apparently causes them to keep discharging far below storage voltage if left a long time (3 months or so), thus destroying them.

I am confident this is what happened to my batteries. They had each been flown six times, then stored for about five months. Then they were charged and the firmware was updated. Then they were stored for the final fatal four months with the buggy firmware installed. Now they are most certainly destroyed.

DJI clearly acknowledges the bug and says it was fixed in the latest release. It's in the release notes. But they take no responsibility for the batteries it destroyed, even though the firmware update was mandatory.

Interestingly, it is probably almost impossible for a battery destroyed by this bug to ever still be in warranty, because it takes almost as long as the warranty period for the bug to destroy a battery. And, it's not the battery that is defective in the first place, it is a firmware update that was applied much later. There is perhaps no warranty on firmware or any damage it causes, despite it being mandatory?

Again did you discharge them to 50% after the 'killer' firmware update before storing? Failure to do so will kill the battery.

 

[tfmkevin]

At the risk of sounding like a nanny, did you try putting them on charge with the DJI-supplied charger for an hour?

Yep. Tried it with each of them. That was the first thing I tried. No LEDs lit, no response to button press or hold. Just stone cold dead. I did all that before I tried removing the tops.

I did find it funny that, after a detailed explanation of the problem and everything I had done and checked, that DJI asked me to send a video showing the problem. I asked if they really wanted video of a dead battery, and asked what they would like to see in that video. They just replied again repeating the request. "Please send a video showing the problem."

I sent a video showing nothing happening when I pressed and held the buttons repeatedly on both batteries, and nothing happening when I plugged each battery in and repeated the process, and nothing happening when I installed each battery in the Inspire and tried the same things.

Then, they asked me to update the firmware.

Uhhhhh...

 

[damoncooper]

Yep. Tried it with each of them. That was the first thing I tried. No LEDs lit, no response to button press or hold. Just stone cold dead. I did all that before I tried removing the tops.

I did find it funny that, after a detailed explanation of the problem and everything I had done and checked, that DJI asked me to send a video showing the problem. I asked if they really wanted video of a dead battery, and asked what they would like to see in that video. They just replied again repeating the request. "Please send a video showing the problem."

I sent a video showing nothing happening when I pressed and held the buttons repeatedly on both batteries, and nothing happening when I plugged each battery in and repeated the process, and nothing happening when I installed each battery in the Inspire and tried the same things.

Then, they asked me to update the firmware.

Uhhhhh...

I understand they were unresponsive when you attempted to charge. But did you leave them alone on the charger for an full hour?

 

[tfmkevin]

Again did you discharge them to 50% after the 'killer' firmware update before storing? Failure to do so will kill the battery.

Failure to do so is not supposed to kill the battery.

First, it is fine to store LiPos fully charged, discharging them to 50% just improves their longevity. Second, these "smart batteries" are supposed to automatically discharge to 50% if they are left unused for more than 10 days. It is the bug in this "smart" firmware that destroyed the batteries. It did not stop at 50%, it just kept on slowly discharging until the batteries were destroyed.

But, to answer the question, yes. I did partially discharge them for storage. That should not matter, however.

 

[tfmkevin]

I understand they were unresponsive when you attempted to charge. But did you leave them alone on the charger for an full hour?

Yes. I tried charging each one for more than an hour. I also tried a different charger in case that was the problem.

Then, when I took the tops off and directly measured the cell voltage with a multimeter, I found cell voltages below 1V. LiPos below 1V are destroyed.

 

[Scotflieger]

I was offering suggestions. You obviously feel greatly aggrieved but venting your anger here won't solve your problem. Personally I won't ignore my main asset for 5 months and not expect some issues.

 

[damoncooper]

Yes. I tried charging each one for more than an hour. I also tried a different charger in case that was the problem.

Then, when I took the tops off and directly measured the cell voltage with a multimeter, I found cell voltages below 1V. LiPos below 1V are destroyed.

I'd try posting on the official DJI FB page. In my view they should replace these for you.

 

[tfmkevin]

I'm actually not angry or aggrieved.

I am asking if other people have had the issue.

I appreciate the comments and suggestions, and I know my original post did not include every detail - mainly because I didn't want to post a novel. So I don't mind at all that people are asking for clarifications and offering suggestions.

I do not view owning an Inspire as a day-to-day responsibility like a child or pet. It is a tool or a toy, and sometimes life requires me to put thise things away for awhile and not give them constant attention.

I also would not own a drone I could not afford to lose, either emotionally or financially. It's a high-risk hobby and some bad things will inevitably happen despite our best efforts.

My batteries are most definitely destroyed. I'm a professional electronic engineer with a deep understanding of batteries and related technology. I also have years of hobby experience building and flying many drones. That hobby and professional experience have me certain that my batteries are destroyed, and fairly confident that they were destroyed by a firmware bug.

So, I am curious whether this has happened to others. If I am correct about the bug, it should have destroyed any battery with the buggy firmware that was stored more than three months or so.

 

[William Fredette]

Don't know that this will be helpful, but it's another data point. I had not used my Inspire from November until a couple of weeks ago. Both of my batteries had been discharged to 50% and then stored. When I pulled them out to charge them, they were unresponsive when I first plugged them into the charger. I put each of them into the Inspire, and tried to power up. The quad didn't power up, but the battery LEDs lit up. Then I put each back on the charger, and each one charged successfully to 100%.

 

[tfmkevin]

Don't know that this will be helpful, but it's another data point. I had not used my Inspire from November until a couple of weeks ago. Both of my batteries had been discharged to 50% and then stored. When I pulled them out to charge them, they were unresponsive when I first plugged them into the charger. I put each of them into the Inspire, and tried to power up. The quad didn't power up, but the battery LEDs lit up. Then I put each back on the charger, and each one charged successfully to 100%.

Sounds like you may have just dodged the bullet on the firmware bug. Apparently the automatic self-discharge is very slow so that it does not generate excessive heat. I'd bet that if you had waited longer your batteries would have discharged until they were dead.

I would recommend keeping an eye on them anyway to be sure they were not damaged by over discharging.

 

[Scotflieger]

STOP BLAMING THE FIRMWARE. You have no proof.

 

[tfmkevin]

You are correct. I have no proof. Just two batteries that were bought new, treated well, and failed at exactly the same time after a firmware update was installed.

There could be a thousand other explanations.

 

[tfmkevin]

You are correct. I have no proof. Just two batteries that were bought new, treated well, and failed at exactly the same time after a firmware update was installed.

There could be a thousand other explanations.

Oh, I forgot, and the DJI release note that says that the firmware has this exact bug fixed in the latest release. But yes. No proof whatsoever.