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Bug: Battery drops from 49% to 7% in less than 5 seconds.
1793 28 2015-3-24
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supasympa
lvl.3

United Kingdom
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I was just out flying very briefly to check one of my I1s before a proper flight tomorrow. My batteries were all charged around 8 days ago and were reporting a charge of 80% each.

I started by hovering at around 5ft 2 meters away from me and just worked rectangle of around 5 meters by 10 meters. I noticed the battery level had dropped to 52% within about one minute of light manouvers. I landed and took off again and noticed the charge had dropped to 49% then as I hovered I noticed the legs on the aircraft come down and it go into land. My battery reading was now 7%.

The battery has probably been cycled 3 times and the other two batteries charged at the same time all look like they had the same charge.

Am I missing something about the batteries or is this as scary as it seems. If I had been flying over 30 meters away anywhere above 20 feet I think I would have a very expensive jigsaw puzzle on my hands.

I'm still using the .16 FW and 1.0.2 of the pilot app.
2015-3-24
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Bob Marley
Second Officer

United States
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What happened when you tried the other battery packs, what were their readings??

Have you updated the batt firmware?

Did the I1 "feel" like it was down to 7%, maybe a simple batt calibration?

2015-3-24
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supasympa
lvl.3

United Kingdom
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@Bob Marley

I haven't tried the other batteries yet. I'll give them a go. The battery firmware was updated along with the .16 update - I haven't gone to .17 yet (too scared).

When you say did it feel like it was down to 7% - I don't really get what you mean. I don't fly my quadcopter on feeling I fly it based on the information I'm given. ;)
2015-3-24
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FlyingSquirrel
lvl.3
Flight distance : 7954751 ft
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Argentina
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supa - wise move on not upgrading to 17. I did and now I have to send my i1 to DJI for service.
2015-3-24
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leostrat_54
lvl.4

United States
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I had a similar occurrence with batteries that I had partially discharged and because of weather didn't use them for 3 to 4 weeks.  Three of the four of them did just what you described.  I charged them up and carefully flew each on down to 20% with no problems, recharged them and have had no problems since.  Did you freshly charge the battery you had problems with just before flying?
2015-3-24
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Dangair
Second Officer

Canada
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Flying squirrel, I updated to 17 and I do experience some issues but I have a few hours of flight so far with no problems beyond the anticipated the temporary GPS loss. I have a question about the battery though, did you notice if all the cells, there are 6, discharged evenly or was one or more discharged more than the others? The reason I ask this is, the battery requires voltage from all the cells to add up to the correct amount this means the batteries cells are balanced. If one or more cells are discharged below operating level there will not be sufficient voltage to maintain operation. This is " the weakest link in the chain theory" . The batteries come with the charger and balancer built in so if the charger/ balancer is defective that can be a problem or if you have a defective cell that won't hold a charge. Do try another battery, if that works fine then you will need to replace the crappy battery.
2015-3-24
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CrabHawk
Second Officer
Flight distance : 7782 ft
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United States
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I've heard of this but never experienced it myself.
2015-3-24
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Colonel Angus
Second Officer

United States
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This is exactly what I had happen testing a tb 47 !!
Sent it back as defective!

The batts are the weakest link always ..
2015-3-24
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supasympa
lvl.3

United Kingdom
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The battery is charging fine again now - but reported some serious problems - which frankly, I don't believe!

Here is a video of the behaviour of the battery after the flight:



It then wouldn't charge for about 20 minutes before taking a charge and behaving normally.

My thoughts - the battery cells are fine. DJI's battery software is crappy!



2015-3-24
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supasympa
lvl.3

United Kingdom
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Some photos of what the Pilot App was reporting:

https://twitter.com/supasympa/status/580435325228593152

Personally I don't believe that the problem is hardware at all I think this is a DJI software issue.
2015-3-24
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markjacobs.talk
First Officer
Flight distance : 120784 ft
United Kingdom
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I would NEVER start a flight with a reported 80% charge - ALWAYS 100%.
What interval is your self discharge set to on that battery? (How many days? - Had it started to go into self discharge?)
Why did you not charge that battery up to 100% before flight?
What level have you previously flown that battery down to? (I notice you have your critical set at 10%)

Sorry... lots of questions but would like to get to the bottom of the problem if possible.
2015-3-24
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Colonel Angus
Second Officer

United States
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supasympa Posted at 2015-3-25 06:12
Some photos of what the Pilot App was reporting:

https://twitter.com/supasympa/status/5804353252285 ...

That's wild I had the same issue and ditched the battery didn't try to recharge just sent it back...

I think.. I don't know what to think .I took no chances and ditched the funky battery I had amongst 7 I won.
2015-3-24
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Colonel Angus
Second Officer

United States
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markjacobs.talk Posted at 2015-3-25 06:27
I would NEVER start a flight with a reported 80% charge - ALWAYS 100%.
What interval is your self di ...


I wonder about what you just posted and I set my batts for 10 days from a full charge to discharge ..
Do you think the battery hit its discharge while in the air??

If so that's whacked as it gets and makes sense.
2015-3-24
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Dangair
Second Officer

Canada
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Don't fly with it at all, send it back it is defective, you will crash your quad. Remember this.... No power no fly! Quads don't auto rotate!
2015-3-24
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markjacobs.talk
First Officer
Flight distance : 120784 ft
United Kingdom
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Colonel Angus Posted at 2015-3-25 12:23
I wonder about what you just posted and I set my batts for 10 days from a full charge to discharge ...

No,  the batteries will not go into discharge whilst flying but from what the OP was saying it had already lost 20% (I'm assuming) of it's charge over the preceding week. That implies to me that maybe the self discharge was set to say 4 or 5 days and it had begun it's cycle of ramping down to storage level.
By then putting the battery in and flying without charging back up to 100% , the discharge cycle was interrupted. This COULD have upset the calibration for that battery and the Inspire did not read the discharge curve correctly over the minutes is was flying.

That's just a hypothesis mind you.  I would run the battery down to circa 8% and then give it a FULL CHARGE. then use it whist keeping a close eye on the individual cell levels whilst under load in flight. A balanced lipo shouldn't really drop more than around 0.1-0.2 between cells. If there is a large imbalance whilst in use then I would discontinue using that pack.
   
2015-3-25
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dshanesmith
lvl.3
Flight distance : 920577 ft
United States
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Just curious, what was the temp when you were flying?
2015-3-25
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leostrat_54
lvl.4

United States
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markjacobs.talk Posted at 2015-3-25 16:21
No,  the batteries will not go into discharge whilst flying but from what the OP was saying it had ...

Mark,

I did exactly what you described.  After I had this issue with 3 out of 4 batteries, I recharged them and carefully flew them down below 20% (2-3 foot off the ground).  I have recharged them several times since then with zero problems.  The battery menu does show an 'over discharge event' on the day they dropped quickly, but nothing since.
2015-3-25
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Acidsnow
Second Officer
Flight distance : 13 ft
Canada
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dshanesmith Posted at 2015-3-25 21:55
Just curious, what was the temp when you were flying?

temperature is a major factor . . .
2015-3-25
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markjacobs.talk
First Officer
Flight distance : 120784 ft
United Kingdom
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leostrat_54@yah Posted at 2015-3-25 23:39
Mark,

I did exactly what you described.  After I had this issue with 3 out of 4 batteries, I rech ...

Glad to hear that........ These batteries DO need calibrating from time to time (as per the manual describes) and you should always start out your flight with a fully charged pack.
2015-3-25
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Fencinales
lvl.2

Colombia
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leostrat_54@yah Posted at 2015-3-25 02:25
I had a similar occurrence with batteries that I had partially discharged and because of weather did ...

Exactly the same happened to me
2015-3-25
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Colonel Angus
Second Officer

United States
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markjacobs.talk Posted at 2015-3-25 16:21
No,  the batteries will not go into discharge whilst flying but from what the OP was saying it had ...

TY Mark for that clarification!
I too will toggle the battery icon and watch the cells like I did when testing each battery seems like great logic to follow for each flight!
2015-3-25
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supasympa
lvl.3

United Kingdom
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markjacobs.talk Posted at 2015-3-25 23:55
Glad to hear that........ These batteries DO need calibrating from time to time (as per the manual ...

Hi Mark

I tried recharging the battery and it eventually started charging again and went back to 100%.
I'm not confident of the battery though.

I looked in the manual and couldn't see how to calibrate the batteries - please could you explain in detail how to do it?
2015-3-27
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supasympa
lvl.3

United Kingdom
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markjacobs.talk Posted at 2015-3-25 06:27
I would NEVER start a flight with a reported 80% charge - ALWAYS 100%.
What interval is your self di ...

I was only doing a quick test of the the aircraft (thank goodness) as I had a flight assessment the next day. So literally just checking the aircraft over - so I thought 80% was a perfectly acceptable charge.

The temperature was 9 degrees c (at least that's what it said on my ananometer).
2015-3-27
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supasympa
lvl.3

United Kingdom
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I've logged (another) ticket with DJI - but not had any response.

DJI's customer service is absoloutely the worst of any tech company I have ever come across. When you're spending circa £3000 I expect much better customer service than is currently offered.
2015-3-27
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markjacobs.talk
First Officer
Flight distance : 120784 ft
United Kingdom
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supasympa Posted at 2015-3-28 01:01
Hi Mark

I tried recharging the battery and it eventually started charging again and went back to  ...

Hi,

Have a look on page 22 of the manual (bottom of page). There you'll find details on battery calibration.
It actually says to calibrate every 10 charges but I do it every 20.
Basically you run the battery right the way down to circa 5% or cut off. I then allow my packs to completely recover to ambient temperature and then give them a full charge to 100%.

With regards to your 'dodgy' pack, as long as you keep an eye on the individual cell voltages during the next few flights you should be fine.

Where is your flight assessment? BNUC-s or RPQ or RPC-L?

Good luck - where in the UK are you?
2015-3-27
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supasympa
lvl.3

United Kingdom
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markjacobs.talk Posted at 2015-3-28 02:07
Hi,

Have a look on page 22 of the manual (bottom of page). There you'll find details on battery c ...

Thanks for the advice Mark.  I did RPQs - passed my flight assessment now I just need to get my Ops manual signed off.
I'm based near Reigate.
2015-3-30
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GB44
Captain
Flight distance : 343848 ft
United Kingdom
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supasympa Posted at 2015-3-30 22:02
Thanks for the advice Mark.  I did RPQs - passed my flight assessment now I just need to get my Op ...

Just out of curiosity, is your RPQ based on specific aircraft or will it be classification of Aircraft as per CAA in the UK.

I am having some issues with EuroUSC regarding Pilot certification as they seem to think that EuroUSC dont have to issue Pilot certification for class of aircraft but rather following flight test of specific aircraft which means in  theory you are not a BNUC-S qualified Pilot to fly other aircraft even if the same model, as EuroUSC are insisting that they flight test all Pilots with all aircraft they propose to fly.

So in essence this would mean you cant fly for any other Operator unless you do further flight tests with specific machines and register those indiviudal aircraft serial numbers.

I have not heard of anything like this before so will be interested to find out what your RPQ actually allows you to fly once issued.
2015-3-30
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supasympa
lvl.3

United Kingdom
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GB44 Posted at 2015-3-30 22:31
Just out of curiosity, is your RPQ based on specific aircraft or will it be classification of Aircr ...

The regulations just changed. Resource group were decent enough to tell me before I took two flight assessments,  a week before I passed my flight assessment.

My understanding of the regulations for all RPAS below 7kg:
You only have to do a flight assessment on a single platform to gain the qualification and be allowed to fly all other <7kg platforms.
However, you'd need to submit amends to your Ops Manual before you have permission to  operate.

You can find all the details here:

http://www.caa.co.uk/application ... =detail&id=6623

Specifically:
"In parallel with the change to the NQE approval system, the CAA-issued Permission for aerial work will also be updated. The current ANO Articles 166 and 167 Permission document is produced in two categories: Permission for SUA not exceeding 7 kg and Permission for SUA of greater than 7 kg but not exceeding 20 kg. Both these Permission documents list the actual type(s) (models) of aircraft that the operator intends to operate. In line with adjusting to the future structure, ‘standard’ permissions will not list specific types (models) but will grant permission to fly any SUA within one or more of the following classes:
a) SUA multirotor with a maximum take-off mass (MTOM) not exceeding 7 kg.
b) SUA multirotor with a MTOM greater than 7 kg but not exceeding 20 kg.
c) SUA fixed-wing with a MTOM not exceeding 7 kg.
d) SUA fixed-wing with a MTOM greater than 7 kg but not exceeding 20 kg.
Within each class, the applicant will be free to vary or add SUA as they wish without the requirement to undertake a practical flight assessment for each individual machine or when adding or changing to a new type (model). Both categories of NQE should make their recommendations to the CAA in one or more of the above classes. Existing Permissions, although currently listing individual aircraft, will automatically have the same privileges."

Hope that helps.
2015-4-2
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markjacobs.talk
First Officer
Flight distance : 120784 ft
United Kingdom
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supasympa Posted at 2015-4-2 19:55
The regulations just changed. Resource group were decent enough to tell me before I took two fligh ...

Correct!......there is absolutely no need to  be reassessed when swapping aircraft within the same group.

2015-4-2
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