Airdata Has me Freaked Out

[spamgnome]

I've been closely monitoring Airdata ever since I had a forced landing resulting from one of my battery cells "collapsing." Now that I'm looking at my battery health more closely, I'm seeing cell voltage deviations of > .1V (sometimes as much as .2V) on ALL of my batteries. None of which have over about 40 cycles on them. I've ALWAYS babied my batteries so neglect is not a real consideration, and I know care and feeding of batteries has been discussed here ad nauseum.
Given this data, are ALL of my batteries bad??? Is this "normal?" If you haven't taken a look at your batteries this closely, I'd encourage you to do so and let me know what you find.

Here's a representative sample from a flight today. Of note, I'm purposely doing a deep cycle of this battery to see if that helps.

 

[GerdS]

No, this is not normal. I would no longer trust into such a battery. If it is not older than 6 months I would try getting a replacement battery on warranty.
If several batteries are showing the same behaviour you should think about your battery handling, if you are doing something wrong...

 

[Meta4]

I'm seeing cell voltage deviations of > .1V (sometimes as much as .2V) on ALL of my batteries.
Given this data, are ALL of my batteries bad??? Is this "normal?"

You are seeing that because it's completely normal and not indicative of trouble ahead.

Of note, I'm purposely doing a deep cycle of this battery to see if that helps.

It probably won't "help" because there's nothing to help.
Stop worrying and enjoy your flying.

 

[Thomas B]

I've been closely monitoring Airdata ever since I had a forced landing resulting from one of my battery cells "collapsing." Now that I'm looking at my battery health more closely, I'm seeing cell voltage deviations of > .1V (sometimes as much as .2V) on ALL of my batteries. None of which have over about 40 cycles on them. I've ALWAYS babied my batteries so neglect is not a real consideration, and I know care and feeding of batteries has been discussed here ad nauseum.
Given this data, are ALL of my batteries bad??? Is this "normal?" If you haven't taken a look at your batteries this closely, I'd encourage you to do so and let me know what you find.

Here's a representative sample from a flight today. Of note, I'm purposely doing a deep cycle of this battery to see if that helps.

I don’t Understand what I am supposed to see on the AirData pic... explain please

 

[GerdS]

You are seeing that because it's completely normal and not indicative of trouble ahead.

No, be sure that is not "normal"!
If you select the "Cells graph" tab you can clearly see that one cell is bad with significantly lower voltage than the others.
My 3 Mavic Pro batteries are from November 2016, have 135 cycles each and are still in much better condition than what I am seeing here.

 

[Meta4]

I don’t Understand what I am supposed to see on the AirData pic... explain please

Click Power on the left of the page, then Battery Cells on the top.
Airdata exaggerates what is a serious cell voltage deviation.

 

[spamgnome]

No, this is not normal. I would no longer trust into such a battery. If it is not older than 6 months I would try getting a replacement battery on warranty.
If several batteries are showing the same behaviour you should think about your battery handling, if you are doing something wrong...

Here's the "fuller story." After my forced landing, I contacted DJI and sent the drone and all the batteries in. This was 8 months from date of purchase. I went back in time and confirmed on Airdata that the issues started showing up about 3 months after initial purchase. Their response was, "Bad battery, but since it's past the 6 months, you're outta luck.
I kind of get it, but the defect was there within the warranty period, so I think they should have honored the warranty. They disagreed.

 

[Thomas B]

Here's the "fuller story." After my forced landing, I contacted DJI and sent the drone and all the batteries in. This was 8 months from date of purchase. I went back in time and confirmed on Airdata that the issues started showing up about 3 months after initial purchase. Their response was, "Bad battery, but since it's past the 6 months, [Language removed by Admin]
I kind of get it, but the defect was there within the warranty period, so I think they should have honored the warranty. They disagreed.

All the more reason to report problems as soon as they occur.
While I empathize, you do, of course, appreciate that the warranty period was expired... if they honor one, where does it stop?

 

[old man mavic]

cant understand why you took off with 34% battery remaining, Oh sorry was this your deep cycle attempt, missed that bit first time around

 

[Brewbud]

Here's the "fuller story." After my forced landing, I contacted DJI and sent the drone and all the batteries in. This was 8 months from date of purchase. I went back in time and confirmed on Airdata that the issues started showing up about 3 months after initial purchase. Their response was, "Bad battery, but since it's past the 6 months, you're outta luck.
I kind of get it, but the defect was there within the warranty period, so I think they should have honored the warranty. They disagreed.

That sucks they wouldn't help you out with at least a discount. Does Europe get a 1-year warranty on the batteries?

 

[Deleted member 94047]

You can't take off with a battery that is already at 34% of capacity and expect the cells to be balanced. Charge it to full first before doing any assesment, charging rebalances the cells.

 

[spamgnome]

You can't take off with a battery that is already at 34% of capacity and expect the cells to be balanced. Charge it to full first before doing any assesment, charging rebalances the cells.

This battery has had unbalanced cells for a while, I just wasn't aware of it until I really started looking into things in Airdata. I took off with 34% in order to attempt a deep cycle, like so many have recommended. Surprisingly, it seemed to help a little.

 

[jrboolander]

Not sure what the tolerences are for DJI smart batteries, but on “regular” lipos a .2 difference is nothing to be concerned about.

 

[Flygmaskin]

This battery has had unbalanced cells for a while, I just wasn't aware of it until I really started looking into things in Airdata. I took off with 34% in order to attempt a deep cycle, like so many have recommended. Surprisingly, it seemed to help a little.

Hi there,

You said that you have these voltage deviations in all your batteries? How many do you have? Up to 40 cycles sure is not alot, especially since you took good care of them.

What difference did the "deep cycle" you performed made?

And also, can you post a flight data log performing a flight with fully charged battery? The specific one you posted before (0K4XF69943035L) would be great!

 

[Deleted member 94047]

This battery has had unbalanced cells for a while, I just wasn't aware of it until I really started looking into things in Airdata. I took off with 34% in order to attempt a deep cycle, like so many have recommended. Surprisingly, it seemed to help a little.

I have performed a deep discharge cycle on two of my batteries. It had good results in one; in the other there were no improvements in terms of cell deviations. But there have been no adverse effects I could see either so I guess it is always worth trying in a battery that is not performing as it should.

Also something I noticed from experience is ambient temperature during flight is a big factor. Two of my batteries show upto .05V deviations between cells when I fly during the day (in around 22 -25 degrees Celsius) but the cell deviations will drop to .02V or less if I fly with them in early mornings in around 16 - 18 degrees Celsius. Avoiding/Minimizing flying in hot weather conditions I think can greatly prolong the life of batteries.

One final note on performing a deep cycle, it is not just about getting the battery to 10% of capacity or a certain voltage. You will have better chances of getting good results if you (1) start with the battery fully charged first and (2) discharge it at a steady rate that doesn't put a lot of stress on the battery. For the later, I put the battery in the AC, power it on and do a near ground hover for the entirety of the discharge. This discharges the battery at a more or less consistent rate. Once the battery is discharged to about 8-10% of its capacity, power it off, let it cool down and charge it back to full.

Having said all that, I have also noticed from experience and a little digging in the logs that DJI batteries are made by different manufacturers. I have found that two of my batteries which are not doing that great are made by the same company while the third one which is in tip-top condition is from a different company. So getting a good battery is a bit of a lottery. If you are lucky, you get a good one, if you aren't - well we know how that goes.

 

[BossBob]

You need to give us the names of the manufacturers so we can all check!

 

[Deleted member 94047]

You need to give us the names of the manufacturers so we can all check!

The log entries about the identity of battery manufacturer are cryptic. If you can decipher the manufacturer's name from this

manu:TL NVT,dev_name:JI02

I highly recommend them. Batteries from

manu:UNWODA,dev_name:J23O

I woudn't.

And these entries are found in the event stream in the mobile DAT file. I am not sure if they are also found in the txt log.

 

[spamgnome]

And these entries are found in the event stream in the mobile DAT file. I am not sure if they are also found in the txt log.

Where can I find these logs? I see .DAT files on my phone, but don't find anything when I search the file for "manu:"

Edit: I looked on the back of the battery, and it says, "Manufacturer: Sunwoda" That's just 1 letter short of what it says in the log excerpt above.

 

[Deleted member 94047]

The DAT files can be found in your mobile device. See here How to retrieve a .DAT
You can read the event stream log using DatCon which you can download on the above website. As for "manu" I think that is just short for manufacturer. Also, on my batteries the manufacturer name is written in Chinese characters. Is the one on yours written in English?

 

[spamgnome]

The DAT files can be found in your mobile device. See here How to retrieve a .DAT
You can read the event stream log using DatCon which you can download on the above website. As for "manu" I think that is just short for manufacturer. Also, on my batteries the manufacturer name is written in Chinese characters. Is the one on yours written in English?

Yes, in English. Regarding DatCon, my PC, due to security issues, will not let me install datcon. The 3 batteries that came with my MA FlyMore combo are all Sunwoda, and a 4th that I bought lightly used on eBay is some other company. So far, THAT battery seems to be the most solid.