bjr981s Posted at 5-25 08:49
Near 25.2 volts is meaningless in that context.

You cannot charge a LiPo or LiHV to its full potential. To do so would require a charge voltage of over 4.2V or 4.4V in the case of an LIHV. Current only flows when there is a potential difference. Most of my batteries drop by 0.2Volts per cell after removal from the charger. As I am sure yours do as well. Ask an Electronics Engineer. Did I forget to mention I am an electronics engineer.   

"You cannot charge a LiPo or LiHV to its full potential. To do so would require a charge voltage of over 4.2V or 4.4V in the case of an LIHV. Current only flows when there is a potential difference. Most of my batteries drop by 0.2Volts per cell after removal from the charger. As I am sure yours do as well. Ask an Electronics Engineer. Did I forget to mention I am an electronics engineer."

You can't just admit you were wrong about the high voltage cells?

Yes a charger uses higher voltage than the cell they charge but the final voltage of the cell tells you a lot about which cell is used.

I don't care if you're an electrics engineer, you're still wrong about the batteries. Stating you're an electronics engineer just makes you come across as insecure about being wrong.

I have 4 and that’s just barely enough for me. Unfortunately they’re so shockingly expensive, you need a bank loan to get more than what comes with the drone

I’m going to hopefully end up with at least 6....

got 3 for the drone and 1 for the goggles. But I am thinking of getting a 4th for the drone......

3 batteries is okay I guess.

Duane Degn Posted at 5-25 09:08
"You cannot charge a LiPo or LiHV to its full potential. To do so would require a charge voltage of over 4.2V or 4.4V in the case of an LIHV. Current only flows when there is a potential difference. Most of my batteries drop by 0.2Volts per cell after removal from the charger. As I am sure yours do as well. Ask an Electronics Engineer. Did I forget to mention I am an electronics engineer."

You can't just admit you were wrong about the high voltage cells?

Hi I did the research on the batteries they are indeed LiPos. As I said I would not know until I had looked at them further.

My dissuasions with you were around the logic you used to say they were LiPos. You were correct but for the wrong reasons.

My research also discovered something disturbing.

The Watt hours DJI state is at a .5C draw. I now understand why they say 100 cycles lifetime.

The batteries are under significant stress. They have compromised on battery longevity for weight /  performance.

I would recommend that you do not consume more than 50% battery in a flight. that may get the cycle count up to 1.5 to 2 times advised. If you do fly down to min battery level you may not find that it makes 100 flights per battery. I certainly will be keeping mine over 50% charge remaining on flights. I also ordered a few more batteries so I can at least enjoy reasonable flight times on an outing.

The batteries are specced at 10C but will not provide the amp hours specified unless you keep the discharge current at 0.5 C or below.

It will be interesting getting feedback from those that fly heavy 3D how many cycles;es they get from the battery packs.


  

bjr981s Posted at 6-18 08:13
Hi I did the research on the batteries they are indeed LiPos. As I said I would not know until I had looked at them further.

My dissuasions with you were around the logic you used to say they were LiPos. You were correct but for the wrong reasons.

"You were correct but for the wrong reasons."

And how did you learn the batteries were LiPos with the right reasons?

Here is my reasoning:
Even without pulling a pack apart (which I've done) you can measure the voltage of the full pack. The full pack voltage confirms the voltage I read from the individual cells.

Just power on a pack and measure the voltage. You'll see it's very close to 25.2V as one would expect with a 4.2V cell pack.


Earlier you stated "DIJI use LiHv batteries not normal LiPos. They have a full charge of 4.4V per cell."

Yet later you say "Near 25.2 volts is meaningless in that context." Why is it meaningless?

What was the right way to learn these were LiPo cells?

Duane Degn Posted at 6-18 18:13
"You were correct but for the wrong reasons."

And how did you learn the batteries were LiPos with the right reasons?

Because after charging a pack the voltage drops. On a LiPo it is normal for a pack to drop to 4.18V per cell after the charge. This happen as the Charge voltage can not exceed the full charge voltage of the pack by very much without damaging the pack. It is extremely rare for a LiPo to hold 4.2V after a couple of minutes after charging as it cools down. In most cases reading 4.2V would mean the voltage meter does not have enough ohms per volt to be accurate enough. Unless you measured it with a calibrated Fluke Multimeter the reading is likely not accurate. Using different LiPo checkers I find a .2 volt variance in most of them. The most accurate is the Futaba BR-3000 checker but its quite expensive.

The best way to determine the characteristics of the Battery is to get the full specification from the vendor. The Nominal Voltage figure will define battery chemistry. The C rating and MAH rating can be somewhat misleading. I formally test batteries on calibrated loads to see how well the C rating and mah rating compare to the spec. I have found very few that comply.

The Definition of the C rating is not a formal stanford so many "adjust" it for marketing. Some advise the C rating as it is for a fully charged battery. Ideally it should be at the nominal voltage.

The C rating is often quoted as a current draw before damage to the battery occurs. This is not correct.

Discharging a LiPo or LiHV battery does damage to the battery. The damage is relative to the current draw and the depth of discharge. Damage also occurs at the sate of charge of the battery. Above and below the nominal voltage. Hence should be kept at storage voltage when not in use.

The C rating is meant to be the current draw where the battery does not brownout. This is a current where the battery can not sustain its voltage at that current draw. (this also accelerates the damage)

It's fairly obvious the the "C" rating of a flat battery is 0. its a relatively linear scale from full charge to depleted.

Remember that the voltage drops as the battery discharges. So the "c" rating drops at the same time.

Another factor is what is the current draw that will allow the full mah rating of the battery to be achieved. Batteries that I have tested do not come anywhere near the rating when approaching "C" current draws. The worst I have tested is Hobbyking Turnigy tx, receiver batteries. Claimed to be 10 to 20 C and in reality less that .5 C. Not a big deal for an RX or TX battery.

DJI actually provide a valid specification that is useful in determining the capability of the battery.

Its the Watt hours max with an associated current draw. In the case for the FPV Drone battery its 44.4 Watt Hours at .5C so any current draw above .5C will prevent you from getting the full capability from the battery. That is 2000mah x 0.5 so 1 Amp divided across 4 motors and the electronics. So is 250ma per motor max assuming 0 for the main electronics.

Hence why the specification is only 100 recycles, as the batteries are under serious loads. Particularly in Manual and Sports modes. And the reduced flight times being experienced by pilots.
         
Hope this is of value.

Cheers

bjr981s Posted at 6-21 22:02
Because after charging a pack the voltage drops. On a LiPo it is normal for a pack to drop to 4.18V per cell after the charge. This happen as the Charge voltage can not exceed the full charge voltage of the pack by very much without damaging the pack. It is extremely rare for a LiPo to hold 4.2V after a couple of minutes after charging as it cools down. In most cases reading 4.2V would mean the voltage meter does not have enough ohms per volt to be accurate enough. Unless you measured it with a calibrated Fluke Multimeter the reading is likely not accurate. Using different LiPo checkers I find a .2 volt variance in most of them. The most accurate is the Futaba BR-3000 checker but its quite expensive.

The best way to determine the characteristics of the Battery is to get the full specification from the vendor. The Nominal Voltage figure will define battery chemistry. The C rating and MAH rating can be somewhat misleading. I formally test batteries on calibrated loads to see how well the C rating and mah rating compare to the spec. I have found very few that comply.

Again I'll ask how did you learn the batteries were LiPo for the right reason?

Duane Degn Posted at 6-22 00:31
Again I'll ask how did you learn the batteries were LiPo for the right reason?

From Previous.

The best way to determine the characteristics of the Battery is to get the full specification from the vendor. The Nominal Voltage figure will define battery chemistry.

I got the battery Spec from DJI.

Duane Degn Posted at 5-22 10:15
"DIJI use LiHv batteries not normal LiPos. They have a full charge of 4.4V per cell."

Not the FPV batteries. The FPV batteries has 4.2V cells.(full charge). A fully charged pack is 25.2V/ (6x4.2V). Maybe other DJI drones have higher voltage batteries but the FPV drone does not.

The .DAT log file contains battery info both before and after the flight; i.e. before and after the interval shown by the .txt log. The following shows an increase in the lowest cell voltage and the pack voltage when the motors were stopped. In this case the lowest cell increased 0.057 volts (from 3.481 to 3.538)  and the pack voltage increased 0.321 volts (from 20.961 to 21.282)

How many drone pack do you guys go through with one goggles pack?

Dji say 110min for the goggles
and 20min per drone pack

That means goggle should last near 5 packs

Is that was everyone is experiencing?

Although I have 6 I'm probably buying more as I only get 8min flying time per battery these days. Chilly weather.

Can anyone tell me what size screws Dji fpv drone shell
And best place to buy them?
I know it’s 2 different sizes.
Daughter was helping mom clean tossed magnet dish with screws box of new props and motion controller from dads desk. I was out of town didn’t notice till I got home 4 days after Waste Management took trash☺️

Daddy’s little helper

Got 6 but unfortunately my spotter never has the time for me to empty all of them

djiuser_YoAhEi7BJ5Bh Posted at 12-16 09:35
Got 6 but unfortunately my spotter never has the time for me to empty all of them

I don't usually fly 3 batteries in the same place unless I'm "practicing".  The effort of going somewhere else to fly is bad too.  Without "missions" to do usually for pay it's not motivating but I don't use the DJI FPV for that.

5 batteries 2 charging hubs AC and DC chargers.

DroneJunkieQc Posted at 1-7 08:02
5 batteries 2 charging hubs AC and DC chargers.

2 charging hubs that can accommodate 3?  That means you should have 6?  Why have multiple DC chargers unless they are designed for other batteries too?

AntDX316 Posted at 1-8 05:56
2 charging hubs that can accommodate 3?  That means you should have 6?  Why have multiple DC chargers unless they are designed for other batteries too?

Each Fly more comes with 1 Hub and 2 Batteries so two of those equals 4 batteries plus 1 included with the drone=5 . One  AC charger and one DC charger.
I have enough with 5 for now.

djiuser_Hs99QmXEZqf4 Posted at 2021-12-2 20:48
Can anyone tell me what size screws Dji fpv drone shell
And best place to buy them?
I know it’s 2 different sizes.

I would call to see if there is a DJI service center around you.
Or call DJI and see if you can order some.
Unless you can borrow a screw from someone who has one to find identical size.

DroneJunkieQc Posted at 1-8 07:43
Each Fly more comes with 1 Hub and 2 Batteries so two of those equals 4 batteries plus 1 included with the drone=5 . One  AC charger and one DC charger.
I have enough with 5 for now.

so buy one more then?

AntDX316 Posted at 1-8 07:57
so buy one more then?

Still never used all 5 at one time so I figure saving the 200$
Hopefully they Drop a Mini FPV, I'm so crossing my fingers.

DroneJunkieQc Posted at 1-8 08:15
Still never used all 5 at one time so I figure saving the 200$
Hopefully they Drop a Mini FPV, I'm so crossing my fingers.

No need for a Mini FPV unless you are indoors but then why not just go outside.

AntDX316 Posted at 1-8 08:38
No need for a Mini FPV unless you are indoors but then why not just go outside.

I want both.
People less scared of a mini.
You can scare the crap out of someone when she screams by in sport mode.

DroneJunkieQc Posted at 1-8 08:46
I want both.
People less scared of a mini.
You can scare the crap out of someone when she screams by in sport mode.

I hardly fly the FPV anymore..  probably for quick intelligence gathering it would be good like how the trail looks like.

AntDX316 Posted at 1-8 10:41
I hardly fly the FPV anymore..  probably for quick intelligence gathering it would be good like how the trail looks like.

I still love it

DroneJunkieQc Posted at 1-12 12:51
I still love it

I can't wait to use it for quick super important intelligence missions that take like 30 seconds to complete until I pack it again.

AntDX316 Posted at 1-12 16:10
I can't wait to use it for quick super important intelligence missions that take like 30 seconds to complete until I pack it again.

Sweet. Endless possibilities

DroneJunkieQc Posted at 1-12 16:41
Sweet. Endless possibilities

I just don't have any quick super intelligence missions to do now

AntDX316 Posted at 1-12 17:02
I just don't have any quick super intelligence missions to do now

I'm up to 6 batteries now. 5 of them just reached 70 cycles each - a total of about 350 flights, so I bought another. And I may go with another fly more combo to bring the total to 8. I fly my fpv drone a lot and field charging isn't really practical because I have to bring all the extra gear....

I'm good with 3 FPV batteries.  It makes me still fly other stuff while they're charging...and they seem to me to charge really fast compared to other DJI batteries.

I have 5 but feel I’m gonna need more.

just bought a 4th batt. and still it's not enough..they drain fast in acro

I am just getting started with drones. What is your average flight time/distance traveled per battery with the DJI FPV?

DAFlys Posted at 2021-4-6 23:39
ouch, 100 cycles,  thats getting expensive to fly.

I'm just using my phone and acting as my own spotter. Need flight time to learn more maneuvers.

I have 4x batteries coming in the mail.. should be here next week.  That makes 12 batteries


And I have 3x Goggles v2

mbze430 Posted at 4-15 16:18
I have 4x batteries coming in the mail.. should be here next week.  That makes 12 batteries
[view_image]

A smart move because unless an fpv racing drone v2 with the same batteries is planned, sooner or later no more batteries will be produced for this drone.
...and how many drones do you have?

I burned through all 3 batteries i had within 33 minutes on my first time out so i bought another 3 last week.
got all charged up & ready to go this weekend & got rained off!
Typical

did anyone decide if they were LiHv in the end?

sh0wtime_FPV Posted at 6-5 10:41
I burned through all 3 batteries i had within 33 minutes on my first time out so i bought another 3 last week.
got all charged up & ready to go this weekend & got rained off!
Typical

I get scared flying in manual mode as it goes super fast.

AntDX316 Posted at 6-11 02:10
I get scared flying in manual mode as it goes super fast.

yes, It takes a lot of skill and training to be able to fly gently and accurately in Manual, especially with such a fast and heavy fpv drone.