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Critical PSA DJI Advises Customers To Fly With Caution When Using TB50 And TB55 Batteries In Drones

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DJI Advises Customers To Fly With Caution When Using TB50 And TB55 Batteries In Drones

DJI Advises Customers To Fly With Caution When Using TB50 And TB55 Batteries In Drones
News2018-10-31


DJI Advises Customers To Fly With Caution When Using TB50 And TB55 Batteries In Drones
DJI Investigating Cause Of Small Number Of Batteries Reporting Incorrect Power Levels

DJI is investigating reports that a small number of TB50 and TB55 batteries have shown incorrect power levels that have led to loss of power mid-flight. Flight safety and product reliability are our top priorities, and we are advising customers to fly with caution when operating their drones equipped with these batteries. In addition, DJI is working on a firmware update that will provide improvements to flight safety for the affected drones.

DJI strongly advises customers to strictly follow regulations that are designed to mitigate the risk of a power failure, including U.S. Federal Aviation Administration prohibitions against flight over people and vehicles, and the U.K. Civil Aviation Authority's offset requirements from people and property. Do not operate over, or in close proximity to, people or property that could be injured or damaged in the event of a power loss. Customers performing non-essential operations may also choose to delay those operations until we are able to provide more information.

DJI is taking this step out of an abundance of caution, and we are urgently working on a mitigation plan to allow customers to confidently use these batteries again as soon as possible. DJI is working on a firmware update for the affected batteries which will provide improvements to flight safety and be made available in the coming weeks. DJI will promptly update customers on the status of these efforts.

In the meantime, customers are advised to check the voltage of their TB50 or TB55 batteries before and during the flight. Instructions can be found below.*

TB55 batteries are used to power the Matrice 200 series of professional drones, while TB50 batteries are used to power the Matrice 200 series and Inspire 2 drones. A small number of customers have reported mid-air power failures while using TB55 batteries, which share similar power management firmware with the TB50. DJI is working with our battery supplier, which developed the power management algorithm for those batteries, to determine the underlying cause of those failures and develop a solution for them.

DJI is reviewing all recent reports of power problems that may be connected to this issue. Any customer who believes he or she may have experienced a related power problem involving the TB50 or TB55 battery should contact DJI customer service at dji.com/support to report the issue.

*Instructions before and during flight:
1. Fully charge the battery according to the indicator on the charger, not the indicator on the battery itself
2. Insert the battery in the drone, power on and check in the app that the voltage is above 4.25V (fully charged)
3. During flight, continue to monitor the voltage of the battery in the battery submenu of the app at all times and ensure it is above 3.7V
content_d4c4a3941718aaa8f905143b493f8211.jpg

4. Plan your flight so as to end the operation and land with at least 3.7V indicated (approximately 30% of full charge)
5. Reminder: Keep the flight within visual line of sight (VLOS) to support a safe return to home
6. Do not fly over people, moving vehicles, or other property that is susceptible to damage
 
For years I have always used 3.3v as the minimum safe in flight voltage, brining my I1 or I2 back to land at around 3.7v but being happy to still be in the air at 3.3v.

Have I been pushing things too far?

What voltage thresholds do you use?
 
For years I have always used 3.3v as the minimum safe in flight voltage, brining my I1 or I2 back to land at around 3.7v but being happy to still be in the air at 3.3v.

Have I been pushing things too far?

What voltage thresholds do you use?

I didn’t write this article. I assume your question is direct to the general audience ?

If so I would agree with your start coming home at 3.7 and land at 3.3 give or take.

I however think in DJI recommendation in this article it’s provided with “an abundance of caution” as there is an issue they are seeing. They need to have the extra buffer because they don’t understand the problem yet.
 
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@MrTVR I believe you stated before you’re set for 10 days before self discharge.

I’m curious have you ever noticed incorrect power levels? I’m guessing no
Example
One battery reading 100% the other say 85%
The problem I think is the self discharge timer and somehow giving false percentage readings.

I’m changing to 10 days
 
Law enforcement using the Matrice have grounded all inservice drones of that model pending the outcome of this research. There are messages in LEO circles spreading the warnings. Most agencies have other models as well, and continue to use them in the meantime.
 
@MrTVR I believe you stated before you’re set for 10 days before self discharge.

I’m curious have you ever noticed incorrect power levels? I’m guessing no
Example
One battery reading 100% the other say 85%
The problem I think is the self discharge timer and somehow giving false percentage readings.

I’m changing to 10 days

I have noticed that the exact point in time at which each battery will start the auto discharge varies a bit. This results in some batteries being slightly more discharged than others if you try to use them during the discharge process. If you feel the batteries at around 9 to 10 days you will notice some are warm (discharging) whilst others are not.

I guess the timer in the battery isn’t crystal based. It’s probably just a simple (cheap) R/C circuit, resulting in inaccuracies.

For this reason I will generally pop all batteries in the charger before use if they have been standing for more than a week or so, just in case.
 
For years I have always used 3.3v as the minimum safe in flight voltage, brining my I1 or I2 back to land at around 3.7v but being happy to still be in the air at 3.3v.

Have I been pushing things too far?

What voltage thresholds do you use?
No - 3.3v per cell is fine as this is under load.
Once landed the cells will rebound to around 3.7v which is fine.
 
Our standard practice is to only fly fully charged batteries. I never fly with a battery that has less than full charge to start and always always always charge battery to full if it has sat more than 2 days regardless of charge state shown on battery.
 
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MrTvR - agree with Ed, 3.3v is within safe range... under normal conditions.

I don't read these notices as the problem being a voltage imbalance between pairs or voltage being the issue. They are suggesting 3.7v as a safety net while the "cause" is examined and they've indicated the cause is associated to FW. Originally the FW issue was thought to be out of sync battery FW to AC / FC firmware. That has expanded to FW associated to how the circuit either communicates or reports.

Optimistically, no incidents and it's been a minimal number reportedly involved and the ordeal will provide an improvement in the FW for a positive outcome for all TB50 / TB55 platforms.

In the meantime, as stated in the other thread of similar subject... On 31 Oct (post #7 above) the notice increased the advisement of caution and limitations. With this type of notice publicly announced, if there was any damage incident, the sUAV shop could experience a stronger legal action taken with the supportive public notices and recognized manufacture acknowledgement. It may not be technically grounding the majority, but it is providing a legal standing difficult to defend.
 
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I'm just guessing here. Since the I2 platform has been around about two years and as far as I know it has not had this problem until now. I'm assuming this is a firmware issue not a hardware issue? DJI announced a firmware upgrade coming soon to fix it? I'm wondering if this problem is only occurring on one of the newer firmware releases? I haven't upgraded my firmware in almost a year. My I2 always has flown flawlessly and I have the "If It ain't broke don't fix it" mentality. I'm on a few DJI forums and Facebook pages. I read quite often of the woes of those upgrading firmware. DJI has released several upgrades with several issues. I think I"ll just maintain my mentality. What do you guys think?
 
I'm just guessing here. Since the I2 platform has been around about two years and as far as I know it has not had this problem until now. I'm assuming this is a firmware issue not a hardware issue? DJI announced a firmware upgrade coming soon to fix it? I'm wondering if this problem is only occurring on one of the newer firmware releases? I haven't upgraded my firmware in almost a year. My I2 always has flown flawlessly and I have the "If It ain't broke don't fix it" mentality. I'm on a few DJI forums and Facebook pages. I read quite often of the woes of those upgrading firmware. DJI has released several upgrades with several issues. I think I"ll just maintain my mentality. What do you guys think?
Correct, everything indicates a FW or lack of FW sync between AC and Batteries. You may be behind enough on FW not to be an issue if all batteries are of same FW version. If you aquire new batteries, they may be problematic if out of sync. The don’t indicate a FW version as fault, but somewhere there apparently was a version that must have applied a modification to the battery logic that indirectly may have caused or brought about this issue... all assumptions, not privy to the internal Engineer discussions.

Reguardless, l’d agree several versions back, I don’t beleive this was a concern.
 
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I have my suspicions this condition may be related to the heating cycle of the battery.

I finished charging my TB50 with the battery charging station. Flew on of 4 pairs fine. Started on the second pair which had 100 percent charge but it did sit out in the colder air a bit before flight. It was about plus 8 C

On inserting into the aircraft it shows 98 percent. But a few seconds after take off the battery dropped to 3.2 or 3.3 volts and In hover started that low. GO4 gave me a warning to land with a critical voltage warning

I did of course. The voltage climbed back up to 4.2.

I reseated the battery and power cycled it only to get the exact same good voltage with motors idle and critical low voltage warning after take off.

I let it hover for a few more min 4 feet off the ground and the error and voltage persisted. I then took those batteries out of circulation. That’s battery pair has only 25 cycles on and has only ever been charged with the charger station. It’s running battery firmware ending in .71 (I’m in the beta and charger station also updates battery to this version)

The other sets of battery’s I left in the helicopter we landed in flew fine.

I know this is a limited data set and it might not even be the same issue as the battery going completely dead. Running beta firmware .300 for i2 right now may also be the source of my issues on this.

But as others have indicated I feeling this likely firmware.
 
As we await the Engineer / Designer’s cause & correction updates. Keep in mind this isn’t a dead battery pair issue, and so far not directly associated to voltage issue. It’s been described as a FW sync issue; which I first interpreted as out of sync between AC and Battery, but now pondering if associated to “how FW” interprets per cell voltage imbalance... weaker theory but possible. The Notice’s recommendation to maintain a minimum 3.7v if you do decide to fly AC is a suggestion to minimize the likely hood of triggering a FW reaction to voltage.

My personal opinion reguarding the recommendation to maintain above 3.7v voltage, might possibly be due to cell variance across cells within the 2x 6S batteries. I’ve noticed the voltage variance more prominent once the battery gets into the 3.5-3.7v range.

Currently from what we know, it’s not a full “no power failure” due to dead batteries... I don’t think I’ve heard any findings on the few incidents of battery condition, only the statements from DJI on FW.

I lean towards FW version sync issues due to how normal operations within Govt, Millitary, or Police update inventory. They follow SOP that mandates compliance & procedures. That process normally indicates any form of updates ( on any inventory) is a minimum of 12-18 months behind release of new version or patch and after in-department verifications. If the DJI interface connection is active (normally not active on Govt.. at least USA) it might have updated partially leaving additional updates pending via Asst2 Prg. I’ve found it odd that most this chatter of failures reguarding this issue has been Govt Agencies and not aerial shops.
 
It may simply be that the majority of m-200 series drones in use are by government agencies and that’s why they have the majority of the reported incidents.
 
It may simply be that the majority of m-200 series drones in use are by government agencies and that’s why they have the majority of the reported incidents.

Not sure what the ratio between Govt / Prvt sector... but from last reference, this all stems from 1 agency, I haven't seen / read that it occured in multiple agencies... the M200 series. Although, this spread over to include the I2 TB50, and that platform is highly used by Prvt sector; I don't have any detail on the I2 & TB50 incidents.

I do beleive the M200 series is strongly used by many prvt sector shops, enough that the problem should crop up in multiple shops both Govt & Prvt Sector.

Incidently, A few days ago I was checking on any update status on either "cause" or FW update corrections. I haven't read anything new, like the matter was dropped. If notices are recommending grounding the M200 & I2 series, you would think it would be actively providing updates and estimates to release updates.
 
DJI Advises Customers To Fly With Caution When Using TB50 And TB55 Batteries In Drones

DJI Advises Customers To Fly With Caution When Using TB50 And TB55 Batteries In Drones
News2018-10-31


DJI Advises Customers To Fly With Caution When Using TB50 And TB55 Batteries In Drones
DJI Investigating Cause Of Small Number Of Batteries Reporting Incorrect Power Levels

DJI issues Firmware Update for TB50 & TB55 to address the problem within Notice.
DJI Issues Firmware Updates For TB50 And TB55 Batteries
 
I have noticed that the exact point in time at which each battery will start the auto discharge varies a bit. This results in some batteries being slightly more discharged than others if you try to use them during the discharge process. If you feel the batteries at around 9 to 10 days you will notice some are warm (discharging) whilst others are not.

I guess the timer in the battery isn’t crystal based. It’s probably just a simple (cheap) R/C circuit, resulting in inaccuracies.

For this reason I will generally pop all batteries in the charger before use if they have been standing for more than a week or so, just in case.

I’ve also noticed the exact same thing as they do seem to have a slight difference in discharge timing.
That’s interesting to me because the purpose of 2 batteries is, even if one battery is lower or higher.
1. Redundancy (how DJI advertised)
2. More consistent power to the inspire 2

I can also see needing 2 batteries to keep that 3.7v and above to be more consistent to operate.

You may be onto something, these 2 ideas may be linked and also could be when they discharge the heat could be doing damage through time and wearing out small solder spots on the circuit boards and causing failure ...
just a thought.
I truly hope this not a HUGE defect and just a firmware solution because I’m sure we all know what that would mean...
Just a theory
 

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