Although I've been taking good care of my Inspire batteries, at least one is showing some signs of weakening. All 4 of them were charged 40-50 times. Not really much, but - to be honest - they're about 3 years old. No warnings whatsoever, questioned battery state checked OK before flight with aircraft idling on the ground. Once in the air, however, the voltage drops rapidly below green zone, without even pushing the throttle much. True, it's cold now and it takes a while until this battery reach it's recommended 25C temp, but the voltage never goes back to green zone and the power rapidly deteriorates. Seems like she's ready to retire. What would be the best way to confirm this suspicion, eventually try to revitalize the battery in question?

For Inspire 1 battery, it is recommended to fully charge and discharge the battery at least once every 3 months or 10 cycles to calibrate the battery capacity and extend its life. Please have a try, if the issue persists, we do not recommend to use it anymore.
Here are more details of how to maintain the battery: http://dl.djicdn.com/downloads/i ... _Guidelines_1.4.pdf

DJI Mindy Posted at 2018-4-9 22:28
For Inspire 1 battery, t is recommended to fully charge and discharge the battery at least once every 3 months or 10 cycles to calibrate the battery capacity and extend its life. Please have a try, if the issue persists, we do not recommend to use it anymore.
Here are more details of how to maintain the battery: http://dl.djicdn.com/downloads/i ... _Guidelines_1.4.pdf

Thank you, Mindy. I will try to perform calibration ...

Hi Matthew,

To me, I have been taking 2 indicators for judging whether a DJI intelligent flight battery is about to retire.

1) The first indicator is the battery temperature difference with ambient temperature after completion of a full battery flying down to about 20% capacity remaining. This is by far the most important indicator that reflects the internal resistance of all cells inside the battery, and hence reflects their status of ageing. The internal resistance will directly affect both flight performance and flight duration, and if worst enough, will trigger Inspire 's 1 flight control protection algorithm due to excessive voltage drop, revealing the "Warning: Motor overloaded, Aircraft will decelerate to ensure safety." notice frequently.

2) The second indicator is the total capacity after deep discharge recharge cycling versus straight out of the box labelled capacity in mAH. I would consider 80% capacity as the threshold in determining whether a battery should be retired.

I have grounded a TB47 and a TB48 battery due to unacceptable internal resistance. Either of them gave more than 35 degree Celsius (63 degree Fahrenheit) temperature increase vs ambient temperature after non aggressive flights. I don't want to risk a mid-air shut down due to Inspire 1's self protection algorithm.

These are my 2 cents. Hope these help.

Happy flying!

Henry

Henry M.Y. Posted at 2018-4-10 05:37
Hi Matthew,

To me, I have been taking 2 indicators for judging whether a DJI intelligent flight battery is about to retire.

Yes indeed, the temperature rise, motor overloaded warnings and voltage drop during even the most conservative flight are the symptoms. I will perform deep discharge cycle, but I think the verdict is obvious. Thank you Henry, you're a gentleman and a scholar, only few of us are left ...

I had an Inspire 1 battery once with 156 charges on it and it still worked like it was new.

Aeromirage Posted at 2018-4-10 14:26
I had an Inspire 1 battery once with 156 charges on it and it still worked like it was new.

Possible, I guess long Canadian winters and batteries unemployed and hibernating for months doesn't help much. I was keeping storage capacity and eye on them, but forgot to perform cycling every 3 month ......

58 cycles on my original Battery.....TB47

almost 3 years old....... Had stored at 30% for 2 weeks....put a full charge on it with OEM 80w power supply.  I had 3 TB48 batts, so they all got cycled all the time.

One flight, 8min in on my Inspire 1, just a HO HUM flight at the local field....as I was going by I heard crackling.....had NO clue what it was....but decided to come land.  Backed her up to the point of take off,
just as I started decent from 10'  I got the critical low battery warning and she shot up to RTH altitude and promptly quit.......fell from 60'.  Totalled

She crashed right in front of me.......immediatley noticed the battery was severely swollen and had come disconnected from connector.  Meaning crash or no crash, the battery was so swollen I could not move it.

Sad day......

rwynant V1 Posted at 2018-4-11 20:53
58 cycles on my original Battery.....TB47

almost 3 years old....... Had stored at 30% for 2 weeks....put a full charge on it with OEM 80w power supply.  I had 3 TB48 batts, so they all got cycled all the time.

Oh, I'm sorry, what a terrible experience ... Makes me worry if one should push the luck with apparent lifespan of TB47/48 batts of about 3 seasons/ 50 cycles average. Ageing is evident, no matter how careful off-season storing and maintenance procedure is employed. I just did cycling and performance field tests ... At least one TB47 reached retirement age with a mere 60% total capacity, two TB48 are within 75%, only one TB48 seems to keep the charge above acceptable 5000 mAh threshold ...

  

rwynant V1 Posted at 2018-4-11 20:53
58 cycles on my original Battery.....TB47

almost 3 years old....... Had stored at 30% for 2 weeks....put a full charge on it with OEM 80w power supply.  I had 3 TB48 batts, so they all got cycled all the time.

Yet, it's hard to believe that the age itself will cause such volatile battery failure. I might be wrong, not knowing much about LiPO batteries. The symptoms suggests an internal shortage, which - in case of LiPO battery - may release enormous amount of energy quickly, fire or explosion in worst scenario ...

That TB47 was fine,  charged fine, showed fine in checking the stats......was not stressing it at all, did not stress it at all.

I have about 30 LiPo flight batteries from 3s to 6s   2200mah to 5000mah......always fly and put away discharged to 3.8 volts per cell...never charge until the night before use.  60 to 100+ cycles on all, and some are 3+ years old.  Never even had one PUFF.

Randy

rwynant V1 Posted at 2018-4-12 10:45
That TB47 was fine,  charged fine, showed fine in checking the stats......was not stressing it at all, did not stress it at all.

I have about 30 LiPo flight batteries from 3s to 6s   2200mah to 5000mah......always fly and put away discharged to 3.8 volts per cell...never charge until the night before use.  60 to 100+ cycles on all, and some are 3+ years old.  Never even had one PUFF.

Just bad luck, I think ... I know you may be not in the mood for getting to the bottom of this, but here's an interesting post about LiPo battery lifespan:

https://inspirepilots.com/thread ... /page-2#post-179394

Matthew.

Reading that,  looks like mine was right inline with that thread........

Thanks!

Randy

If they've sat for awhile starting up the ac at the 4 foot take off height and then hitting the left stick 3/4 will usually show the overload. I take mine down to 5%, let them sit for an hour and recharge. Airdata is something i use to keep an eye on cell performance. I believe there is a free version of the app too.