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TB 47 battery problem after 51 charges
2789 21 2017-1-27
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RichJ53
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I was flying yesterday and put one of my TB 47 batteries into my Inspire 1 V2 for a quick flight.  The battery was acting very strangely and was giving me poor readings in the Go App. I did not get any warnings in my App and the battery details (advanced settings page) said it was normal.  The battery has been maintained correctly and deep cycled every 20 charges. The first 15 charge cycles were only using the battery to about 50% (DJI Ken recommends). I hate to toss out a expensive battery, but this one is very suspicious and do not trust it anymore. The last screen shot is just after powering off the Inspire motors and it appears that loading has something to do with my problem.

DJI or anyone else having this problem before would be nice to hear from you.

Note the TB 47 4500mAH  is only showing total capacity of 3687mAH now.  

I am posting the screen shots below,
Thanks
Rich

IMG_0093.jpg IMG_0094.jpg IMG_0095.jpg


2017-1-27
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Highasakite
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Rich, how about just draining it and recharging it? Maybe the cells just need balanced. Or , I hate to say it but maybe it is just time to send it to battery heaven. I think that the people who get over 100 charges on their's must use and charge them almost every day.  I ALWAYS fully charge a battery or batteries 1/2 hour to 1 hour before I intend to use them.  Ken.
2017-1-27
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DJI-Jamie
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Have you already tried the deep drain/recharge to see if that helps? How long have you had the battery thus far?
2017-1-27
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RichJ53
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DJI-Jamie Posted at 2017-1-27 15:41
Have you already tried the deep drain/recharge to see if that helps? How long have you had the battery thus far?

Hi Jamie,
Yes, I have drained my battery to less the 5% and I put this battery into service March of 2016.  I noticed that the Go App no longer gives us the running battery history logs. So I guess there is no way to see if the battery experienced an event correct?

Thanks for responding

All the best
Rich
2017-1-27
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RichJ53
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Highasakite Posted at 2017-1-27 12:01
Rich, how about just draining it and recharging it? Maybe the cells just need balanced. Or , I hate to say it but maybe it is just time to send it to battery heaven. I think that the people who get over 100 charges on their's must use and charge them almost every day.  I ALWAYS fully charge a battery or batteries 1/2 hour to 1 hour before I intend to use them.  Ken.

Hi HS
Yah, I have done the drain and cycle routine with this battery. If anything it got worse
The battery has not been abused or really over worked and never saw a battery warning or reduced motor warning. It was working okay right up to the end....

You might be right time to retire this one.

Have a nice weekend
Rich
2017-1-27
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R&L Aerial
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If you dare, pull the top of and you will see a little black wire has come unhooked. I've had this happen to several batteries, very poor design
2017-1-28
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Highasakite
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I agree with you R&L, I had that same problem with one of my old TB48s. I wonder what that wire does? It is connected to the little circuit board just under the battery cover(or lid) and travels down in between the battery cells, and that is where it becomes disconnected from. I tried to post a picture of the problem but I got a little frustrated when it said the file was too big. You are the only other person that I've heard mention this, so far.  Is there any way you could post a picture of the disconnected wire? Have a great day! Ken.
2017-1-28
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RichJ53
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R&L Aerial  Posted at 2017-1-28 06:18
If you dare, pull the top of and you will see a little black wire has come unhooked. I've had this happen to several batteries, very poor design


Okay great thoughts fella's and thank you for the imput.
So, this battery is not under the warranty period and at this point I decided to take it apart to see if anything was out of place. There are several Youtube videos showing others taking the top off the DJI TB 47 battery. (most of them do not use any special tools) and cut up credit cards to pry the battery apart.
I would like to say that if you have the right tools, it is very easy to remove. So you old hands at making repairs can ignore the following information and is useful to the new members.
Let's start by listing the tools I used and the links to buy them from IFIXIT

1. iSesamo Opening tool, this is a metal prying tool that has great grip and large flat surface to get underneath the item you are removing.
https://www.ifixit.com/Store/Tools/iSesamo-Opening-Tool/IF145-130
2. Metal Spudger Set, Just the right amount of spring to pop out components and pry up against sticky adhesive.
https://www.ifixit.com/Store/Tools/Metal-Spudger-Set/IF145-017
3. iFixit Opening Tool, this tool is great for prying and getting the angle needed for the most stubborn parts. This tool is made from plastic and will not damage the pieces you are taking apart.
https://www.ifixit.com/Store/Too ... ng-Tool/IF145-335-2
Using these tools the top came off without any damage to the parts. Lifting up the top to one side you can see that all of the wiring and connectors were intact. DJI uses a lot of blue glue on the circuit board components and to secure the masking tape to the wires. (pain the butt to take off) They also use this glue to hold the four (4) metal screws into the plastic top plate. Be careful not to strip out the holes and take your time removing them.

1.        Top removal using pry tools
2.        Remove yellow tape holding the connector plug. Disconnect the Molex multi pin balance port connector connecting the circuit board. you will notice the power LED does not function when this is disconnected.
3.        Remove the four (4) screws holding the circuit board to the top plastic cover. The main negative (black) battery wire is short making the one screw in the corner difficult to remove. Be careful not to short out against anything while getting to this screw. set aside top cover.
4.        Remove the  masking tape from the top of the battery protecting the wiring. In this case I only removed the two strips over the terminal board to access the wires that I wanted to check.
So after inspecting all of the wires, the large gauge main battery wires are soldered to the terminal board and the smaller signal or control wires are routed near by. Most likely one is a thermistor to monitor battery temperature and maybe center taps to monitor cell voltage.
So in my case I did not find anything wrong with the wiring or quality of the construction of my battery. Actually I was very impressed to the detail taken that insures against vibration during normal use.  
I remember reading that removing the Molex connector (balance plug) will reset the Intelligent circuit.  After thinking about this fact, I reassembled my battery and will deep cycle it one more time. Hopefully I will see some improvement (if resetting works)
photos shown below and if I missed something please let me know.
Rich  

IMG_8304.JPG IMG_8298.JPG IMG_8299.JPG IMG_8303.JPG IMG_8301.JPG IMG_8300.JPG IMG_8302.JPG
2017-1-28
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RichJ53
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Highasakite Posted at 2017-1-28 07:28
I agree with you R&L, I had that same problem with one of my old TB48s. I wonder what that wire does? It is connected to the little circuit board just under the battery cover(or lid) and travels down in between the battery cells, and that is where it becomes disconnected from. I tried to post a picture of the problem but I got a little frustrated when it said the file was too big. You are the only other person that I've heard mention this, so far.  Is there any way you could post a picture of the disconnected wire? Have a great day! Ken.

Ken,
I did not find this to be the case on my battery. Please see my detailed post and photos.

Rich
2017-1-28
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Highasakite
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Hi Rich, thank you for the quality photos! The wire that R&L Aerial and I were referring to is the small double black one that has the yellow tape on it on the top of the board. It was disconnected from somewhere down inside the battery cells. I'm not sure if it affects anything but I'm sure it is there for a reason, just don't know the reason. Just FYI. By the way, do you ever get the "file to big to download" message, and how can I overcome that obstical? Ken.
2017-1-28
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RichJ53
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Highasakite Posted at 2017-1-28 13:20
Hi Rich, thank you for the quality photos! The wire that R&L Aerial and I were referring to is the small double black one that has the yellow tape on it on the top of the board. It was disconnected from somewhere down inside the battery cells. I'm not sure if it affects anything but I'm sure it is there for a reason, just don't know the reason. Just FYI. By the way, do you ever get the "file to big to download" message, and how can I overcome that obstical? Ken.

Hi Ken,
Yes, the black wire that you and R&L were referring to was connected and in good condition. The wire is soldered in to the top of the circuit board and glued with yellow contact glue. This may have been the improvement to stop the broken wires that were being reported?

Okay, if you are adding photo files to the forum be sure to resize them (using a App) to ensure they are not larger than allowed under 2meg. If you have Microsoft office installed on your computer, use the  send-to feature (right click menu) and send the photo(s) to a mail recipient. This will bring a popup box to save the photos at a reduced file size, small,l medium, large or original. This is a pretty easy way to get the photo size useable for the web.

All the best
Rich
2017-1-28
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RichJ53
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So, now after doing the reset inside the battery and deep cycling it one more time. You can see the photos as the flight progressed. Note the total capacity did not improve and when the motors were started the voltage dropped 25.6V to 22.7 within the first minute.  This was a hovering test at about 26 feet max the total flight time was 12:28 minutes down to 10%.

upon conclusion this battery is grounded
Thanks for following and if you have any comments or questions please feel free to ask.

Rich

IMG_0097.jpg IMG_0099.jpg IMG_0100.jpg IMG_0102.jpg IMG_0103.jpg IMG_0104.jpg IMG_0105.jpg
2017-1-28
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Henry M.Y.
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RichJ53 Posted at 2017-1-28 20:37
So, now after doing the reset inside the battery and deep cycling it one more time. You can see the photos as the flight progressed. Note the total capacity did not improve and when the motors were started the voltage dropped 25.6V to 22.7 within the first minute.  This was a hovering test at about 26 feet max the total flight time was 12:28 minutes down to 10%.

upon conclusion this battery is grounded

Hi Richard,

Li-Po batteries' optimum operating temperature is around 40 degree C, and usually wear out faster in cold environment.

After all, you may ground the TB47 and use it as in-the-field power source for charging remote controllers / tablets / phones. The 80Whr capacity of this TB47 can still serve you well for such purposes.

Henry
2017-1-28
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Cmartin3977
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I wouldn't call down to 5% a deep discharge, you need to run that down to where it won't power even a small light bulb.  No power coming from the battery at all.  Then recharge.
2017-1-29
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Highasakite
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Hi rich, thanks so much for the photo upload pointers! Also thanks for trying everything everything imaginable to cure the battery problem, and posting ALL of your results. This is a great lesson for all R/C pilots. An innocent looking battery can cause serious problems , personnel , property and aircraft damage none of which we want any part of! Thanks again, Ken.
2017-1-29
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RichJ53
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Henry M.Y. Posted at 2017-1-28 21:03
Hi Richard,

Li-Po batteries' optimum operating temperature is around 40 degree C, and usually wear out faster in cold environment.

Hi Henry,

Good point you are making. I know this past summer we had some very hot flying sessions and now in the cold weather it could have taken a toll on this battery pack. Although I am very careful during handling and so on...
I find it strange the total capacity dropped so much. Makes me wonder about the quality of the LiPo cells..   
Good idea to use this for other device charging....  Thank you sir

All the best
Rich
2017-1-29
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RichJ53
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Cmartin3977 Posted at 2017-1-29 05:55
I wouldn't call down to 5% a deep discharge, you need to run that down to where it won't power even a small light bulb.  No power coming from the battery at all.  Then recharge.

5% is lower than DJI recommends but I could try dropping it to 0%.  I personally do not think anything will change.

Thanks for the heads up
Rich
2017-1-29
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RichJ53
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Highasakite Posted at 2017-1-29 09:27
Hi rich, thanks so much for the photo upload pointers! Also thanks for trying everything everything imaginable to cure the battery problem, and posting ALL of your results. This is a great lesson for all R/C pilots. An innocent looking battery can cause serious problems , personnel , property and aircraft damage  none of which we want any part of! Thanks again, Ken.

Hi Ken
no problem, I hope you could understand the photo resizing suggestions as I reread my instructions and not sure they were very clear.

Sharing this information hopefully can help others if they run into battery issues.

All the best
Rich
2017-1-29
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RichJ53
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Cmartin3977 Posted at 2017-1-29 05:55
I wouldn't call down to 5% a deep discharge, you need to run that down to where it won't power even a small light bulb.  No power coming from the battery at all.  Then recharge.

I ran the battery down until there was no life at all. Put it back on the charger immediately and the first LED started to flash again.  So after completely charging it again the life came back to this battery (so far) even after starting the motors, the voltage held  
see screen shots of my testing so far showing the capacity coming back to 4090mAH

Rich

IMG_0106.jpg IMG_0107.jpg
2017-2-2
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RichJ53
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Highasakite Posted at 2017-1-29 09:27
Hi rich, thanks so much for the photo upload pointers! Also thanks for trying everything everything imaginable to cure the battery problem, and posting ALL of your results. This is a great lesson for all R/C pilots. An innocent looking battery can cause serious problems , personnel , property and aircraft damage  none of which we want any part of! Thanks again, Ken.

check out my last test
Rich
2017-2-2
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Highasakite
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Wow, Rich! Persistence really pays off. Thanks. Ken
2017-2-5
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Focus4
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Cmartin3977 Posted at 2017-1-29 05:55
I wouldn't call down to 5% a deep discharge, you need to run that down to where it won't power even a small light bulb.  No power coming from the battery at all.  Then recharge.

DJI recommends discharging to 8%. Never discharge to 0.
2017-2-16
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