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Battery TB48 - Unbalanced Cells or Electronic Failure

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Close call this weekend, while comparing different props, I had a TB48 with 12 previous charge cycles, no mistreatment suddenly fail producing a full electrical failure causing the Inspire 1 to fall dead to the ground.
This occurred on a Inspire 1v2 but could be any LiPO HV battery pack on any model.

Several batteries were charged up to full capacity per the 6 pack M600 battery charger. Started the 4th battery flight. When starting up the Inspire, after about 45-60 seconds a warning popup appeared indicating a battery failure and to land immediately. Since I hadn't taken off yet, it was showing 97% with 1 cell noticeably lower (.4 volt est). I powered off, removed and reseated battery; powered up and no error messages. At this time, I assumed I had a battery pack out of cell balance and my intentions were to fly it till 20%, bring it down and hover it to exhaust battery until forced to land and then let it's fan slowly take it further down to 5% before recharging and maybe correcting the cell balance.

Took off, flew for 6 minutes when a message popped up regarding battery but then cleared and I continued for another 10 minutes for a 16 minute flight, brought it down for 5 foot hover and to visually watch blade's dish for uneven blades and for any vibration... purpose of flights were to test different props. The battery was showing 18%, and suddenly cut off and dropped dead to ground. It hit the concert driveway, stayed on all 4 feet. Quick inspection of Z3 camera (left X5 or X5Raw off for prop tests) showed no impact on camera's underside. Only damage was Rt Motor Arm had slightly tilted inward and required realignment. Inspected AC, inserted 5th battery and proceeded to fly 2 more batteries with normal operations. Very fortunate it wasn't at 200 feet when failure! Also very impressed the I1 could take a 5 foot straight drop and have it's shock absorber legs absorb the impact.

Question of ponder: Is the sudden electrical cut-off due to the uneven cells or battery electronics board?
IF so, how far out of balance will trigger this undesired action and secondly, should it just force a land like a normally exhausted battery?

To see if battery balance & condition can be restored, I've removed the I1 battery top and installed a balance lead. Using a standard LiHV charger, performed a 1.5a (very low) balance operation. I left this morning before complete, but it appeared to be slowing bringing all cells back into balance. I'll later perform a few Charge/Discharge operations on the LiHV Charger to verify condition.

One thing I have noticed on the TB48 & 47's is that they quickly drop on their rated capacity when examining through the DJIGo App. After cycling on a LiHV Charger they capacity returns to a much higher mAH and cells are restored to a balanced voltage.

I'm wondering if the larger cell difference was cause of error message and electrical cut off. When the 1 cell dropped below flight voltage it cut off. ?? My guess, I'll see if I get an error message after balancing the cells.
 
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Glad to here no damage was done. Thank God it did it at 5 feet. I always Over for at least one minute before I take off and I always check the battery cells.
 
Wouldn't it be nice if DJI actually put a proper balance lead on their ridiculously expensive "smart" batteries? I know I've seen it somewhere on this forum, but would you mind pointing to the info on adding a balance plug to a TBXX battery?
 
Close call this weekend, while comparing different props, I had a TB48 with 12 previous charge cycles, no mistreatment suddenly fail producing a full electrical failure causing the Inspire 1 to fall dead to the ground.
This occurred on a Inspire 1v2 but could be any LiPO HV battery pack on any model.

Several batteries were charged up to full capacity per the 6 pack M600 battery charger. Started the 4th battery flight. When starting up the Inspire, after about 45-60 seconds a warning popup appeared indicating a battery failure and to land immediately. Since I hadn't taken off yet, it was showing 97% with 1 cell noticeably lower (.4 volt est). I powered off, removed and reseated battery; powered up and no error messages. At this time, I assumed I had a battery pack out of cell balance and my intentions were to fly it till 20%, bring it down and hover it to exhaust battery until forced to land and then let it's fan slowly take it further down to 5% before recharging and maybe correcting the cell balance.

Took off, flew for 6 minutes when a message popped up regarding battery but then cleared and I continued for another 10 minutes for a 16 minute flight, brought it down for 5 foot hover and to visually watch blade's dish for uneven blades and for any vibration... purpose of flights were to test different props. The battery was showing 18%, and suddenly cut off and dropped dead to ground. It hit the concert driveway, stayed on all 4 feet. Quick inspection of Z3 camera (left X5 or X5Raw off for prop tests) showed no impact on camera's underside. Only damage was Rt Motor Arm had slightly tilted inward and required realignment. Inspected AC, inserted 5th battery and proceeded to fly 2 more batteries with normal operations. Very fortunate it wasn't at 200 feet when failure! Also very impressed the I1 could take a 5 foot straight drop and have it's shock absorber legs absorb the impact.

Question of ponder: Is the sudden electrical cut-off due to the uneven cells or battery electronics board?
IF so, how far out of balance will trigger this undesired action and secondly, should it just force a land like a normally exhausted battery?

To see if battery balance & condition can be restored, I've removed the I1 battery top and installed a balance lead. Using a standard LiHV charger, performed a 1.5a (very low) balance operation. I left this morning before complete, but it appeared to be slowing bringing all cells back into balance. I'll later perform a few Charge/Discharge operations on the LiHV Charger to verify condition.

One thing I have noticed on the TB48 & 47's is that they quickly drop on their rated capacity when examining through the DJIGo App. After cycling on a LiHV Charger they capacity returns to a much higher mAH and cells are restored to a balanced voltage.

I'm wondering if the larger cell difference was cause of error message and electrical cut off. When the 1 cell dropped below flight voltage it cut off. ?? My guess, I'll see if I get an error message after balancing the cells.

The TB48 had 2 cells .5 to .8 volt under the other 4 cells. The low amp balance operation took about a full day but was impressed they all balanced out equally. Performed a discharge down to 3.7per, 22v pak again at low .2a. Recharged and hovered I1... all cells remained even. Recharged on DJI I1 charger and again impressed the capacity was back to 5400mah, previously a full charge was 4750mah. Performed 3 sets of charge and minimal flight / hover to see if battery would cut off and each cycle pulled down to 3.45v 9% load... 3.7v landed no motors but fan.

I'd say it's a well functioning TB48 now.
 
Wouldn't it be nice if DJI actually put a proper balance lead on their ridiculously expensive "smart" batteries? I know I've seen it somewhere on this forum, but would you mind pointing to the info on adding a balance plug to a TBXX battery?
I"ll hunt the thread down, but I also can PM you the email of the person that makes the custom DJI balance leads.

I would agree, I'm fine with their charger and smart data/ log battery operations. But I would like a pop off access panel or easy means to perform lipo maintenance operations like balance or discharge.

The TB48 / 47 aren't bad, but the I2 M210 TB50 / 55 are basically not serviceable. I took a bad TB50 apart and think I can cut a sm access panel to remove and install balance lead. BTW.... the I2 has reversed wiring on the balance lead so don't use a TB48 custom lead on TB50.
 
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Wouldn't it be nice if DJI actually put a proper balance lead on their ridiculously expensive "smart" batteries? I know I've seen it somewhere on this forum, but would you mind pointing to the info on adding a balance plug to a TBXX battery?

I looked around and couldn't locate any TB48 Balance lead discussion beyond a few of us mentioning it on various threads.

This is a link that goes directly to Rich's post on DJI Forum where he discusses both the out of balance / low cell and the custom lead he's made to allow balancing / discharging the TB47/48 batteries. From this thread you should be able to obtain the info & balance lead.
If you need Rich's email, PM me an I'll send it over to you.

POLL: Would you purchase a harness to fix TB-47/8 batteries??
 
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I looked around and couldn't locate any TB48 Balance lead discussion beyond a few of us mentioning it on various threads.

This is a link that goes directly to Rich's post on DJI Forum where he discusses both the out of balance / low cell and the custom lead he's made to allow balancing / discharging the TB47/48 batteries. From this thread you should be able to obtain the info & balance lead.
If you need Rich's email, PM me an I'll send it over to you.

POLL: Would you purchase a harness to fix TB-47/8 batteries??
Thanks for searching that out for me. I found these two images on here a while ago. Might be helpful if others are looking for the same sort of info:

QrUxnah.png

cell 1: pad 1 & 2
cell 2: pad 2 & 3 etc...

inspb1.JPG
 
Wouldn't it be nice if DJI actually put a proper balance lead on their ridiculously expensive "smart" batteries? I know I've seen it somewhere on this forum, but would you mind pointing to the info on adding a balance plug to a TBXX battery?

Hi mate, did you ever successfully rebalance your TB47? I have one that has one cell 0.1-0.2 A out of balance. Flattening to 0% and recharging using DJI charger didn't work.
 
Hi mate, did you ever successfully rebalance your TB47? I have one that has one cell 0.1-0.2 A out of balance. Flattening to 0% and recharging using DJI charger didn't work.
The balance lead is a custom lead made by using the connector off an expired TB47/48 battery circuit board lead. This is required due to small DJI connector.

With custom balance lead, pop the top off, unplug the lead & plug in custom balance lead. Alligator clips to Pos & Neg Battery terminals and connect to charger.

A standard charger can restore several TB47/48 battery issues.
Good Luck!
 
The balance lead is a custom lead made by using the connector off an expired TB47/48 battery circuit board lead. This is required due to small DJI connector.

With custom balance lead, pop the top off, unplug the lead & plug in custom balance lead. Alligator clips to Pos & Neg Battery terminals and connect to charger.

A standard charger can restore several TB47/48 battery issues.
Good Luck!

Thanks for the reply, I appreciate the encouragement!
I don't have the harness or much experience with batteries, I was wondering how other Doug went as he might not be too far away... (also down under)
 

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