Cell broken

[Tony Parson]

First, hello guys and gals! I'm from Dayton Tn. I had a couple 3DR Solo's and sold them because to much trouble and headaches. I bought a DJI Phantom 3 standard and I got it all up to date. Charged the battery and this warning keeps coming up. I called DJI and they didn't have much to say except send the battery and get a replacement if I wanted. I took it out 4 times now with this battery but I've not flown it to far and only went about 150 feet up. The battery last for at less 20 minutes. Do you guys think it's save to keep using or just send it in? Here's a couple screen shots. And I did drain the battery all the way down to about 5% and then recharged it. And since I did that I'm no longer getting that warning but the first 2 cells are noticeably lower than the other two, see picture below even when it has a 100% charge. Thanks for any info on this.

 

[solentlife]

It seems strange that model flies for at least 20mins but says cell broken.
The battery is a 4 cell battery and 1 cell broken would seriously affect and most likely you would not be able to fly.
As I understand it - the two sets of contacts have different function. The main where you charge through are the main power to fly. The smaller contacts are the telemetry data contacts. I would test the main contacts with a meter to see what voltage you have when full charged. This should be at or near 17.4v. If it is 13v or similar - then one cell has failed but still making circuit.
If the voltage shows 17.4 or near - then I would suggest cleaning the telemetry contacts of battery and model to see if that clears the error message .....

Something is wrong giving the error message but model still flies ????

Nigel

 

[Tony Parson]

Here is a current picture after a full charging cycle. You can see the difference in each cell.

 

[solentlife]

Well that shows it as good ...

What is the DJI Go app warning now ? Still there or gone ?

To get battery to 100% charge - that last little bit - switch on the battery when charging which then over-rides the default that occurs at near high charge state.

Nigel

 

[Tony Parson]

Well that shows it as good ...

What is the DJI Go app warning now ? Still there or gone ?

To get battery to 100% charge - that last little bit - switch on the battery when charging which then over-rides the default that occurs at near high charge state.

Nigel

Now there's no warning. Thanks for the info. I'm going to try to get it to charge the rest of they way like you suggested!

 

[QuadcopterCrazy]

Maybe just a fluke. Just keep an eye on it.

 

[Phantom-Paul]

If DJI have offered to replace it is it worth taking the risk of it failing in flight and having your bird crash to the ground . At the very least you will wreck a great aircraft but at worst you could hit and kill someone.
The phantoms & batts are pretty clever if it says somethings not right it probably isn't.

Sent from my SM-G900I using PhantomPilots mobile app

 

[solentlife]

It is not uncommon and even DJI state it - that battery contacts gets dirty, oxidised or just generally make bad contact and need cleaning. I strongly suggest that is what happened here.

The voltage display of cells shows no cell problem. I agree that for peace of mind a replacement may be good idea - but its debatable in this case I reckon.

Nigel

 

[Tony Parson]

I got ahold of the DJI dealer I bought this drone from, he replaced the bad battery no question asked. Thanks for all the info on this.

 

[stuka75]

Cant recall. Is the critical cell difference .07 or .7? I've read so many posts in the last few months my brain is glutted.

 

[solentlife]

Critical cell difference is when you get into 10ths of a volt not 100ths.But of course this may ddepend on what DJI battery FW decides.

LiPo's are used in so many models and there us a wealth of info online about them. Some so-called info especially on some forums is just rubbish but generally good.

A standard LiPo cell is 4.2v full charged with overcharged at 4.3v. But a DJI cell is what is generally called a HV LiPo, High Voltage ... which full charge voltage is designed at 4.35v. So far I have not found a reliable source to indicate the overcharge limit.

Normal cells 4.2 or 4.35 versions will show slightly different full charged results across a pack, not unusual to find it range up to 0.05v ... but if it ranged 0.5v - then you have a problem cell.

What can cause this ? Various factors, could be cells getting hard worked and degrading, could be high charge rate overheating a cell, could be poor balancing mode or even not using balance mode when charging. DJI have taken the step of removing from user control of charging. They have passed balancing and terminating charge over to the battery FW. Personally I do not like this but have no choice but live with it.
It is not unusual to find one of the inner cells going down first - it has less chance of dissipating heat and heat is one of the worst enemies.

The answer to the question therefore is 0.07v is not a nice number, but it is acceptable and worth keeping an eye on to see if it worsens. The 0.7v figure is bad and careful checking of charge needed to see why. If charger is good - then battery is soon failing.

Fly with care with such battery, look to replace asap and the first indications of course will be reduced flight time / performance.

Hope the above helps.

Nigel

 

[stuka75]

Critical cell difference is when you get into 10ths of a volt not 100ths.But of course this may ddepend on what DJI battery FW decides.

LiPo's are used in so many models and there us a wealth of info online about them. Some so-called info especially on some forums is just rubbish but generally good.

A standard LiPo cell is 4.2v full charged with overcharged at 4.3v. But a DJI cell is what is generally called a HV LiPo, High Voltage ... which full charge voltage is designed at 4.35v. So far I have not found a reliable source to indicate the overcharge limit.

Normal cells 4.2 or 4.35 versions will show slightly different full charged results across a pack, not unusual to find it range up to 0.05v ... but if it ranged 0.5v - then you have a problem cell.

What can cause this ? Various factors, could be cells getting hard worked and degrading, could be high charge rate overheating a cell, could be poor balancing mode or even not using balance mode when charging. DJI have taken the step of removing from user control of charging. They have passed balancing and terminating charge over to the battery FW. Personally I do not like this but have no choice but live with it.
It is not unusual to find one of the inner cells going down first - it has less chance of dissipating heat and heat is one of the worst enemies.

The answer to the question therefore is 0.07v is not a nice number, but it is acceptable and worth keeping an eye on to see if it worsens. The 0.7v figure is bad and careful checking of charge needed to see why. If charger is good - then battery is soon failing.

Fly with care with such battery, look to replace asap and the first indications of course will be reduced flight time / performance.

Hope the above helps.

Nigel

Thanks Nigel