So my standard capacity P4P battery has a bad cell or two... Is it a throw away?

[Donald Brent]

It looks like the standard battery that came with the drone has a bad cell (possibly 2). With a full charge, one cell reports about 0.2v below the others. I say possibly two because I get the warning message twice, but the other cells all seem to be within 0.01v of each other so I don't know. There is no swelling, punctures or any other physical damage. It has also never been completely discharged. And it's probably only had about 30 or less charge cycles.

My question is, since it is well out of warranty, is it safe to use this battery as a bench battery for firmware updates, ground testing upgrades and that sort of thing (no flying). Temp seems ok. Battery seems to take a charge ok. Just seems a waste to have to dispose of it entirely (properly of course).

Thanks,
Don

 

[FlyingUser]

If it doesn't swell, or go to very deep voltages, it should be OK for the bench for maybe another year.

 

[FlyaDrone I2]

Have you any means of performing a discharge cycle down to at least 50% capacity?
Phantom Angel is one of the best dedicated discharge devices available. DJI guidelines state a 50% discharge every 20 cycles is best maintenance practice for battery life.

 

[With The Birds]

Have you any means of performing a discharge cycle down to at least 50% capacity?
Phantom Angel is one of the best dedicated discharge devices available. DJI guidelines state a 50% discharge every 20 cycles is best maintenance practice for battery life.

I have never seen 50% as a DJI recommended discharge level for battery maintenance. I have seen 8% and even to leave the AC idling untill it turns off in the instructions and on the DJI forums. Neither are necessary for LiION chemistry and certainly of no benefit in calibrating the battery level % indicator. You will probably find the recommendation is a carry over from the older mah counting method of capacity monitoring. The fuel gauging and impedance track algorithms that are employed in current DJI batteries make the deep discharge a waste of time using up charge cycles.

The phantom angel is a beautifully made device but it’s use with the current packs is of no benefit. Simply set you days to discharge to 1 day and relax. Save your charge cycles for flying.

 

[FlyaDrone I2]

@With The Birds
So why does DJI sell a $1k Inspire 2/Matrice 200 battery charge station that has both 50% & 25% discharge levels programmed in? And why does DJI recommend 50% as a storage level condition and 25% as travel level charge?
Have you read the battery manuals?

Phantom 4 series Intelligent Flight Battery Safety Guidelines page 3 "Battery Storage" 1. Discharge the battery 40-65% if it will NOT be used for 10 days or more. Same page "Battery Maintenance" 3. Fully charge and discharge the battery at least once every 3 months to maintain battery health.

The auto discharge function that you put all your faith in takes 3 days to complete even if you set it to begin after 1 day, that equals 4 total. So in fact the Phantom Angel discharge device (30 mins/battery) actually has a very useful service for battery health.

The above information which I include is directly from the P4P battery maintenance guidelines documentation. BTW, written logs of documentation for these battery maintenance procedures is required for part 107 pilots.

 

[With The Birds]

@With The Birds
So why does DJI sell a $1k Inspire 2/Matrice 200 battery charge station that has both 50% & 25% discharge levels programmed in? And why does DJI recommend 50% as a storage level condition and 25% as travel level charge?
Have you read the battery manuals?

Phantom 4 series Intelligent Flight Battery Safety Guidelines page 3 "Battery Storage" 1. Discharge the battery 40-65% if it will NOT be used for 10 days or more. Same page "Battery Maintenance" 3. Fully charge and discharge the battery at least once every 3 months to maintain battery health.

The auto discharge function that you put all your faith in takes 3 days to complete even if you set it to begin after 1 day, that equals 4 total. So in fact the Phantom Angel discharge device (30 mins/battery) actually has a very useful service for battery health.

The above information which I include is directly from the P4P battery maintenance guidelines documentation. BTW, written logs of documentation for these battery maintenance procedures is required for part 107 pilots.

Perhaps you should ask DJI.

40% is a better storage SOC for max life, perhaps the 50% is intended to give some margin for self discharge (chemistry) and powering the BMS SOC in low pawer standby mode.

25% is probably to meet air freight regs (cargo).

The full discharge is a waste of time- it is certainly not needed to calibrate the current battery management electronics. It could, and with limited prospects of success, get a few more cycles out of an ageing pack that might get slightly more balanced cells as a result.