Reconditioning batteries

[UgashikBob]

RoyVa:
The batteries I had over 100 multirotor flights with were Glacier 3S 35C 5300mah lipos. However a Glacier 6S 30c 6000mah dropped my 680 Tarot out the sky after 30 some flights and the Taranis telemetry nailed the sagging cell. DJI has no logging provisions to show a sagging cell and probably never will because its much more profitable to keep selling high dollar lipos.

 

[RoyVa]

I have 2 batteries and they each have around 160 recharges
I'll be honest I am not very comfortable flying with 160 recharges; However only now started to be seriously worried, especially regarding 1 battery in particular...
The one battery had its first major 'incident' the other day. The percentage went from like 40% to 0% in a split second, no error in the stock DJI app, I just saw it flashing red saying 0% and it did the hard auto landing it does normally at like 16-17%. (The auto landing you can't disable). LUCKILY the issue occurred when I was like 2ft above the ground as coincidentally I was coming in to land anyways.

Watch that battery the drops from 40% to O. Mine started doing that and I dint realize it until I had two auto landing due to loss of power. Twice I dint make it back home but thankfully the "Find my Phantom worked and I was able to get it out of a neighbors yard two blocks away one time and the second was even luckier... Out of wood in a bush tree 10 ft off ground after crashing through the trees. Discarded that battery after testing still showed good but would drop from. 65 % to 8 % and craft would autoland on low battery.

 

[yorlik]

. ....Discarded that battery after testing still showed good but would drop from. 65 % to 8 % and craft would autoland on low battery.

Discarded like gone with the trash or discarded like in bottom of your junk box in the garage?

If still in your possession, feel free to donate it to me to test theory why they do this. In exchange, I will report back to this group the findings.... These batts MAY not be unfixable.....

 

[RichWest]

@yorlik - If I had a bad battery you'd already have a test subject.

I'll plug in my bird this weekend and check charge counts, I've had the bird for nearly 10 months and have 3 batteries.

I have to agree with Yorlik, it's either the charger itself or the smart board limiting the charged capacity. Either way I'm getting around 12-14min flight times at less than 20% indication. Interesting part is the 2 month younger battery is the one that runs down quickly.

 

[jumanoc]

I do not thrust DJI's peak values for make total discharge and risible 300 cycles . bla bla.. Real scenarios show an average cycles of 30-60 with healthy batteries. Myself learned on hard way a month ago. A new battery (12 cycles) failed suddenly... App showed 48% charge but my bird dropped from 20 mts. It landed near deep water by 2 meters. It landed over some tree branches. No previous alert.... looked like auto-landing but 3 times faster plus wobbling.. App showed "Phantom Connection Lost" while I was still looking the Phantom descend (100 mts away). I found it 28 minutes later still recording and the motors trying to spin... Battery had 18% remaining. Since that episode it is scary to fly with that battery but I've tested it flying 2-3 high meters and after 5 cycles... never failed again. In Naza Assistant battery shows 97% health and the 3 cells are balanced perfectly .... ??????

 

[RichWest]

@jumanoc - Since we are talking batteries and from my experiences, you need to insure the signal pads on the battery and the contact posts within the bird are cleaned often. Poor contact has attributed to false readings for many, resulting in at location landings. Basically as you described during and after, i.e. no further issues.

 

[jumanoc]

@RichWest - I've flown Phantoms since Jan-2013. Never ever had a similar issue. I keep contacts clean, check wires, screws, cables fitted... as my pre-flight verification. This one was the first scary and non-explainable issue.

 

[RichWest]

@jumanoc - Your example mimicked communication errors others have experienced, i.e. "I found it 28 minutes later still recording and the motors trying to spin... Battery had 18% remaining."

No problem, saw you were a veteran flyer prior to posting, but thought it was worth mentioning as a PSA to others as well. My apology for offering help...

 

[jumanoc]

No matter... R, I just wanted to clarify that IMO it was a battery issue .... May be watching the event video helps: (BTW, like your Avatar ... it looks like my dog before lunch)

 

[yorlik]

j, why do you blame the battery for the video shown? low batt does not rotate 2 revs then come down? no indication your reported 45% batt went any lower either?

seems perfectly clear to me you yawed the crap out of it to the point you set up horrendous vrs and it simply wobbled and fell due to pilot error? looks like something I might do if flying after consuming a case of beer!

am i missing something?

 

[jumanoc]

j, why do you blame the battery for the video shown? low batt does not rotate 2 revs then come down? no indication your reported 45% batt went any lower either?

seems perfectly clear to me you yawed the crap out of it to the point you set up horrendous vrs and it simply wobbled and fell due to pilot error? looks like something I might do if flying after consuming a case of beer!

am i missing something?

Yeah... that looks like VRS... but when phantom went down controls were middle untouched I didn't yaw for those crazy revolutions...the falling speed could do that. It was not descending by stick move.... 100 ft away LOS and video showed "Phantom Connection Lost" while I was looking the bird... In other forum discussion is around instant loose of power... may be a bad contact... but not VRS. IMO. Thanks for your approach.

 

[RichWest]

Back on subject, here is my battery info. Personally I think the number of discharges are way off, possibly restarted count when batteries received a FW upgrade back about 4 or 5 months ago. I have about 70 hours worth of P2V+ videos...

 

[yorlik]

why do you feel this no of charges is inaccurate??

lets see... 76+76+61=213 charges......

if each 'full charge' is 20 minutes of flight, then 213*20= 4260 minutes off flight time....

4260/60= 71 hours of flight time...

you have about 70 hours of recordings....

seem to match up pretty well...

do you disagree or not understand what dji calls a 'discharging time?'

did i miss something?

 

[RichWest]

I have never been able to get more than 18 minutes per charge, in the beginning. When they initiated the battery FW upgrade it's more like 14 min max. Looked it up, Oct. 31, 2014 was when they updated the battery FW.

FWIW, I calculated the same as you but using 15 min as the average. That's about 50 hours.... Really doesn't matter, should have kept a flight log to know for sure. Wish I would have logged the battery info month to month as well. Honestly I'm not unhappy, considering everyone else's poor performance. Live and learn.

 

[RichWest]

@yorlik - Battery 3 indicated a failure yesterday. I knew I shouldn't have gotten involved in this discussion...

Will check it one more time in a few days. If it fails again I'll send it to you.

 

[Tails_Up]

BINGO!

I totally agree. A sagging cell is not necessarily a bad cell, just not charged all the way. Once undercharged by too much, it probably will never get 'balanced' back to full charge by the dji circuitry, and thus the batt is prematurely called bad.

I saw this in my 100% electric 35kwh lipo battery too....

Agreed too this theory needs testing. I've offered....

My experience is that at some point you get a battery error, and that's the end of the show. You can charge/discharge all you want, but the error never goes away. And frankly, do you really want to fly on a sketchy battery? I like to hike out to scenic spots and fly over pretty inaccessible terrain, so an iffy battery is just risking the bird. When you're getting less than 15 minutes of flight, you're on your way to a bad day. So hey big spender, drop a few clams for a couple of new ones. It will make you less nervous.

 

[RichWest]

@yorlik - Battery is dead, cell error... Did fly it for 10 minutes at low altitude and then at 30% it attempted to auto land. I maintained control until 20%, which was rapid decrease.

The battery has puffed, but would be happy to send it to you for your observation or recovery. Send me a PM with shipping address...

 

[yorlik]

PM SENT. TNX

 

[justin00]

I fully agree there are issues with the batteries. I can't get to 100 cycles with an original battery. Those that you are getting over 100 cycles would you mind sharing where, what mfg, model and cost with us. Just may have to give em a go. Thanks Bob.

Not really sure the info you are requesting... but I just fly normaly... usually going full speed and doing 360's, 180's etc etc for the entire flight.. so giving em a good work out... maybe 3 times I've bothered to run them down to 0%.. (instead of every 10 or 20 flights or whatever it says)
I always stop flying at 18% just before autoland, except maybe 2 or 3 times... if I stop early I always make sure they are at approx 40%.
didn't really do anything special... suprised so many people are only getting ~50 cycles.....

They are also always stored in my drone case, just a normal plastic heavy duty case, with the lid open so they don't get to hot.

Got it last october in 2014 and 75% of the time its been warm, maybe 20-30c, flown in some 40c days and a few really cold days.. always stop when it rains, except for a light rain on handful of occasions. no crashes or anything major.

 

[yorlik]

Rich, your batt arrived here with 1 more charge cycle listed and volts of 3824,3838,&3834. Like your 7/3/15 post above, cell 1 is way lower than the others. Your batt#2 is similar so may be close to same failure? anyway, it is interesting that the 'puff' is slight, but center section is like rock hard extended side - not soft like other puffyness I have felt... interesting.

Of course assistant is locked on "damaged cell" pop up still. I am wondering if that can be cleared with disconnecting the cells - will eventually find out.

I will charge it then discharge on my ICE charger/cycler and see how many mah come out. then I will charge it and see how much goes in; will plan to cycle it maybe 5 times like this as a complete 3S2P battery, then go back and do same to each of the 3 cells together, then go back and do each of the 6 cells individually. Will be interesting to see what we find. I will do this in spare time so will take a month or so maybe, but I will post results.

Side note, it is interesting that some folks swear their batts charge on the dji charger in about 2 hours; I measured mine and no matter what battery, it put out about 900ma during charge... Tells me a full charge should take 4-5 hours (of course a 1/2 charge from 50% to 100% would be 2 hours)..... EDIT: just charged a batt and dji supply - got almost too hot to hold; knowing 1 amp won't do that on a 4amp rated supply just measured with a clamp on ammeter around the 12v output of dji charger: 4.3amps! But previous in line digital meter readings were always around 1 amp... put in line and both went down to 1amp again! So the internal drop resistor in my digital meter is about 3x the resistance of the internal dji battery! Wow! I tried 3 other meters with similar results. Just goes to show test results can be significantly off due to the minutiae!