Best battery discharge method?

[WithTheBirds]

Thanks for posting this its a very good reference.

But be advised that the voltages they use are for LiPo batteries. The DJI batteries are LiHv and have a higher charge voltage than LiPos. 4.4V rather than 4.2V

So don't get anxious over the fully charged cell voltages displayed in the battery status of the DJI Go 4 app. They are not overcharging. They are different chemistry.

Cheers

Understood, I thought HV LiPO was 4.35V? The chemistry isn't significantly different and the performance at and approaching the discharged end of the cycle is identical. You might agree, as seems to be the case, the same handling practices are just as relevant to both HV and standard LiPO's. That extra 150mv does give a nice capacity boost. I have on occasion accidentally taken a standard LiPO over 4.2V without apparent ill effect but I wouldn't recommend it.

 

[WithTheBirds]

They are called intelligent as there is circuitry in the battery that causes a discharge to storage voltage after a programmed delay setting, and they have an activate button to display the current charge %.

Unfortunately the intelligence circuitry monitors the battery voltage. The act of monitoring actually very slowly drains the battery. This is why the battery safety manual recommends a cycle every 3 months. Leaving the battery to discharge longer than this time will result in battery damage.

There is no absolute safety automation in the drone that auto lands that can not be overridden by the operator. The low battery RTH can be aborted by the operator. The "Must Land Now" auto landing can be overridden by the operator by holding the throttle stick up. Usually done to prevent an auto landing over water.

In standby mode the micro controller draws 0.5 uA at a VCC of 2.2V so it would take a long time to take the pack down to a level it might be damaged. The self discharge of the cells is almost certainly a greater contributing factor.

 

[BJR981S]

Yeah, fair enough but it would be good to have accurate, proven information in regard to Battery Care best practices. How does typing a few paragraphs in a discussion forum in any way "diminish the fun" of flying our drones?? Your "golfing" analogy doesn't really make any sense.

If you want the correct procedure for care of DJI batteries then read the DJI battery safety guidelines for your relevant drone.

Don't listen to any of us or google or anything other than what the manufacturer recommends.

The battery safety manuals are available in the download links for each DJI drone product.

Older DJI batteries are LiPos newer are LiHvs. Everyone will advise based on what products they have owned. Internet reference will always provide generic information and do not take into account how the battery technology is implemented.

For instance my Phantom 2 had 6 Lipo Cells as they were 3S2P packs. So even if a cell completely failed the parallel cell would keep the drone aloft so you could land it. The new Inspire 2s have parallel packs for the same reason.

Take the guesswork out of the equation and download the safety manual relevant to your drone from the DJI website. And operate to the manufacturers procedures.

As we like to describe it in the IT business. RTFM.

There is good information in this thread regarding the generic principles that you should read like the points on discharge depth and battery longevity. These are basic guideline on letting you determine your priorities of flight times over battery longevity.

Cheers

 

[deleted member 877]

You might find this to be a source of enlightenment.... An easy read with all the basics covered.. How to Prolong Lithium-based Batteries - Battery University

Now that's what I'm talking about - the author certainly does have outstanding credentials. Going forward I won't be discharging below 25%. Many thanks @WithTheBirds for the reference.

 

[WithTheBirds]

Now that's what I'm talking about - the author certainly does have outstanding credentials. Going forward I won't be discharging below 25%. Many thanks @WithTheBirds for the reference.

The biggest advantage with this is if your flying regularly you can just leave the packs to charge untill just before your next flight.... Storing at 20+% isn’t a problem.

 

[kabs]

They are called intelligent as there is circuitry in the battery that causes a discharge to storage voltage after a programmed delay setting, and they have an activate button to display the current charge %.

Unfortunately the intelligence circuitry monitors the battery voltage. The act of monitoring actually very slowly drains the battery. This is why the battery safety manual recommends a cycle every 3 months. Leaving the battery to discharge longer than this time will result in battery damage.

There is no absolute safety automation in the drone that auto lands that can not be overridden by the operator. The low battery RTH can be aborted by the operator. The "Must Land Now" auto landing can be overridden by the operator by holding the throttle stick up. Usually done to prevent an auto landing over water.

BRJ981S thanks for the elucidation, I am beginning to see that I have to depend on these forums to help me get insider knowledge as part of my advance in my new and exciting hobby.

 

[BJR981S]

In standby mode the micro controller draws 0.5 uA at a VCC of 2.2V so it would take a long time to take the pack down to a level it might be damaged. The self discharge of the cells is almost certainly a greater contributing factor.

That is an assumption based on the Micro-controller itself. Not the complete circuitry to implement the micro-controller function. DJI have done some strange things over the years with their implementations.

I have 8 Mavic Pro batteries. After 3 months of storage the press the button display shows 2 lights 50% charged as you would expect. But putting them on the charger only the first light flashes showing a <25% charge.

So at least an additional 25% of the charge is drawn down while in storage passed the 50% expected after 3 months. I suspect why the manual states that it needs to be depleted and re charged every 3 months.

I don't know if you ever owned a DJI Phantom 2 Vision Plus. They had to be flown or at least powered up within 6 months otherwise the Firmware in the Vision transmitter would erase.

My Nephew has had issues with one of his Mavic Pro batteries after it was not used for an extended time. After charging it would report battery error in the Go 4 App and one cell was marginally lower than the others. By fully discharging and recharging it would work OK but he cannot do a basic from storage to full charge anymore. He has to go through the Full discharge every time now. I suspect that one cell got damaged in the extended storage. Other people have reported the same issue with the Pro batteries.

I have many Walkera drone smart batteries and the "Smart" (not as smart as DJI) circuitry for this is driven off cell 1 of the pack. Causing balancing issues. You have to charge the batteries for these with the pack turned on. But they do have a physical switch that disconnects the smart cct so they can be safely storage charge, stored for 12 months plus.

I have several standard LiHv batteries and smart chargers that support them the default charge voltage on them is 4.4 Volts. I think 4.35 is the "relaxed voltage" that the batteries display after they quiesce post charge. My LiPos drop to about 4.15V within an hour of charge. Interestingly enough still well balanced.

I have thought about overcharging them slightly to increase the quiesced charged state but its not worth the risk of an expensive model.

Cheers

 

[WithTheBirds]

If you want the correct procedure for care of DJI batteries then read the DJI battery safety guidelines for your relevant drone.

Don't listen to any of us or google or anything other than what the manufacturer recommends.

The battery safety manuals are available in the download links for each DJI drone product.

Older DJI batteries are LiPos newer are LiHvs. Everyone will advise based on what products they have owned. Internet reference will always provide generic information and do not take into account how the battery technology is implemented.

For instance my Phantom 2 had 6 Lipo Cells as they were 3S2P packs. So even if a cell completely failed the parallel cell would keep the drone aloft so you could land it. The new Inspire 2s have parallel packs for the same reason.

Take the guesswork out of the equation and download the safety manual relevant to your drone from the DJI website. And operate to the manufacturers procedures.

As we like to describe it in the IT business. RTFM.

There is good information in this thread regarding the generic principles that you should read like the points on discharge depth and battery longevity. These are basic guideline on letting you determine your priorities of flight times over battery longevity.

Cheers

Have you read the safety guidelines... it’s not all good. They state batteries must be fully discharged to take in an aircraft- wrong. No airline enforces or required this for cabbin baggage. Air cargo has specific requirements yes. They also say ideal storage temp is 22-28 deg. No. The cooler the better for best life. And it goes on.

 

[BJR981S]

BRJ981S thanks for the elucidation, I am beginning to see that I have to depend on these forums to help me get insider knowledge as part of my advance in my new and exciting hobby.

You're welcome.

I started flying fixed wing nitro RC about 40 years ago and you needed to join a club to fly. Club instructors were the source of knowledge and education. When I first turned up for my first flight I had the elevators reversed. I thought that that was they way they needed to be. With drones the requirement to join clubs to learn to fly has been eliminated. But that leaves a big gap in the education process. With club instructors they had to earn their instructor wings and pass complex knowledge and practical flight tests. It was also mandatory that all members joined the MAAA (international model association) and held public liability insurance.

That leaves forums like this to gather information. Unfortunately there is no knowledge test to pass to give information on the forums. So it is a mixed bag.

Once you have been a member for a while you will be able to pick the members that provide good advice. But even they sometimes make mistakes as the technology and implementations change so quickly. I myself have been caught out many times by being gapped by a new technology that I have not experienced before. I guess this is what makes this hobby so exciting.

Enjoy the hobby. My advice to newcomers is to buy a cheap drone and actually learn to fly. The automation on these camera drones at some time will fail you. If you can fly manually you have a much better chance of rescuing your expensive camera drone in an emergency.

Or buy a WLToys V911 helicopter. You can fly that indoors and it has no automation other than a flybar and a gyro. It will teach you to fly very competently.

Helicopters and Drones share the same stick controls. Fixed wing is completely different.


Cheers Brian

 

[WithTheBirds]

That is an assumption based on the Micro-controller itself. Not the complete circuitry to implement the micro-controller function. DJI have done some strange things over the years with their implementations.

I have 8 Mavic Pro batteries. After 3 months of storage the press the button display shows 2 lights 50% charged as you would expect. But putting them on the charger only the first light flashes showing a <25% charge.

So at least an additional 25% of the charge is drawn down while in storage passed the 50% expected after 3 months. I suspect why the manual states that it needs to be depleted and re charged every 3 months.

I don't know if you ever owned a DJI Phantom 2 Vision Plus. They had to be flown or at least powered up within 6 months otherwise the Firmware in the Vision transmitter would erase.

My Nephew has had issues with one of his Mavic Pro batteries after it was not used for an extended time. After charging it would report battery error in the Go 4 App and one cell was marginally lower than the others. By fully discharging and recharging it would work OK but he cannot do a basic from storage to full charge anymore. He has to go through the Full discharge every time now. I suspect that one cell got damaged in the extended storage. Other people have reported the same issue with the Pro batteries.

I have many Walkera drone smart batteries and the "Smart" (not as smart as DJI) circuitry for this is driven off cell 1 of the pack. Causing balancing issues. You have to charge the batteries for these with the pack turned on. But they do have a physical switch that disconnects the smart cct so they can be safely storage charge, stored for 12 months plus.

I have several standard LiHv batteries and smart chargers that support them the default charge voltage on them is 4.4 Volts. I think 4.35 is the "relaxed voltage" that the batteries display after they quiesce post charge. My LiPos drop to about 4.15V within an hour of charge. Interestingly enough still well balanced.

I have thought about overcharging them slightly to increase the quiesced charged state but its not worth the risk of an expensive model.

Cheers

Correct- I am relying on the SOC specs. I haven't seen anywhere near that level of discharge on any of my packs. I don't think I have left them three months though. I have the luxury of being able to pretty much fly all year round where I am.

I suspect you are right re your Nephews battery- as you likely know once a cell drops below a certain voltage (varies but 2.5V seems to be the point for most liPO's) it doesn't have to stay there long before it is irreversibly damaged. It may seem to charge ok and even be balanced with respect to the other cells in the pack but the IR will be higher and the voltage will drop faster than the other cells once the pack is loaded.

I wouldn't deliberately charge a LiPO above the manufacturer voltage rating- it is probably asking for trouble.

My first DJI quad was a P3P... I flew mainly RC Helis prior to that, dumb LiPO's. That how I learnt, the hard way in many cases, how to get the most out of them. They were ridiculously expensive when I first started using them, the batteries are big and if you get 60 flights you are lucky- that is doing everything right (10C min discharge rate usually).

 

[WithTheBirds]

You're welcome.

I started flying fixed wing nitro RC about 40 years ago and you needed to join a club to fly. Club instructors were the source of knowledge and education. When I first turned up for my first flight I had the elevators reversed. I thought that that was they way they needed to be. With drones the requirement to join clubs to learn to fly has been eliminated. But that leaves a big gap in the education process. With club instructors they had to earn their instructor wings and pass complex knowledge and practical flight tests. It was also mandatory that all members joined the MAAA (international model association) and held public liability insurance.

That leaves forums like this to gather information. Unfortunately there is no knowledge test to pass to give information on the forums. So it is a mixed bag.

Once you have been a member for a while you will be able to pick the members that provide good advice. But even they sometimes make mistakes as the technology and implementations change so quickly. I myself have been caught out many times by being gapped by a new technology that I have not experienced before. I guess this is what makes this hobby so exciting.

Enjoy the hobby. My advice to newcomers is to buy a cheap drone and actually learn to fly. The automation on these camera drones at some time will fail you. If you can fly manually you have a much better chance of rescuing your expensive camera drone in an emergency.

Or buy a WLToys V911 helicopter. You can fly that indoors and it has no automation other than a flybar and a gyro. It will teach you to fly very competently.

Helicopters and Drones share the same stick controls. Fixed wing is completely different.


Cheers Brian

Remember your first phantom flight? I couldn't stop laughing at how strange it felt- took a while to grasp the concept that I could let go of the sticks and the thing would just sit there. The helis were a maximum of three miscalculations and maybe 7 sec (if you were lucky) away from crashing the whole time you had them in the air. You probably never turn just using rudder input either. I don't miss having to fly the same pattern as the fixed wings with no hovering when at a club field though.

 

[BJR981S]

Have you read the safety guidelines... it’s not all good. They state batteries must be fully discharged to take in an aircraft- wrong. No airline enforces or required this for cabbin baggage. Air cargo has specific requirements yes. They also say ideal storage temp is 22-28 deg. No. The cooler the better for best life. And it goes on.

I think that you will find DJI are relying on common sense for Drone batteries. The airlines cannot advise that LiPo batteries must be discharged for flight as cabin baggage as that would include Laptops, Cellphone tablets etc. Most airlines actually provide USB charging for these devices.

DJI are not differentiating on your behalf the choice of cabin baggage or checked baggage.

The rules for Lithium batteries (all Chemistries) for travel in Cargo holds (Includes Checked Baggage) is Global. Hence stated by DJI.

The rules for checked and cabin baggage is up to the individual airline to impose additional safety requirements if they deem appropriate. So DJI don't state an airline by airline policy. Just the generic international one.

Qantas policy is that No lithium batteries are allowed to be included in checked baggage. They must be brought on board as cabin baggage. This is to allow cabin staff to address any issues that my entail.

They (Qantas) do not specify that the batteries must be at storage charge or below. They also don't state that overcharged batteries are disallowed.

They assume that we are responsible travellers and do not want to put ourselves or the aircraft at risk. We are drone pilots not terrorists.

Do we need to be advised for everything that we do in proscriptive legal terms? Do we take unsafe actions because we are not obliged to by proscriptive legal terms?

Common sense is always a good guide for our behaviour. Although I must admit some drone pilots stretch that idea of common sense to the breaking point. Like flying above the clouds at ridiculous altitudes. Or in cities next to helicopter landing pads.

Where did you read the cooler the better? I have not seen that reference.

Cheers

 

[WithTheBirds]

I think that you will find DJI are relying on common sense for Drone batteries. The airlines cannot advise that LiPo batteries must be discharged for flight as cabin baggage as that would include Laptops, Cellphone tablets etc. Most airlines actually provide USB charging for these devices.

DJI are not differentiating on your behalf the choice of cabin baggage or checked baggage.

The rules for Lithium batteries (all Chemistries) for travel in Cargo holds (Includes Checked Baggage) is Global. Hence stated by DJI.

The rules for checked and cabin baggage is up to the individual airline to impose additional safety requirements if they deem appropriate. So DJI don't state an airline by airline policy. Just the generic international one.

Qantas policy is that No lithium batteries are allowed to be included in checked baggage. They must be brought on board as cabin baggage. This is to allow cabin staff to address any issues that my entail.

They (Qantas) do not specify that the batteries must be at storage charge or below. They also don't state that overcharged batteries are disallowed.

They assume that we are responsible travellers and do not want to put ourselves or the aircraft at risk. We are drone pilots not terrorists.

Do we need to be advised for everything that we do in proscriptive legal terms? Do we take unsafe actions because we are not obliged to by proscriptive legal terms?

Common sense is always a good guide for our behaviour. Although I must admit some drone pilots stretch that idea of common sense to the braking point. Like flying above the clouds at ridiculous altitudes. Or in cities next to helicopter landing pads.

Where did you read the cooler the better? I have not seen that reference.

Cheers

As you probably know LiPO’s tend to become less stable when fully discharged although the outcome is more likely they might simply puff up rather than perform an unscheduled rapid and spectacular deconstruction as can be the case when fully charged.

I can’t seem to locate the paper I read in temp and aging, my recollection it was from LG or Panasonic research. I did find the table from battery university which I have copied here. I did recall seeing higher numbers on the other research I read.

These numbers are for 12 months storage with the exception, where noted, if the effect of keeping a LiPO at 100% SOC at 60deg C (an unlikely event).

 

[BJR981S]

Remember your first phantom flight? I couldn't stop laughing at how strange it felt- took a while to grasp the concept that I could let go of the sticks and the thing would just sit there. The helis were a maximum of three miscalculations and maybe 7 sec (if you were lucky) away from crashing the whole time you had them in the air. You probably never turn just using rudder input either. I don't miss having to fly the same pattern as the fixed wings with no hovering when at a club field though.

Hey a fellow helicopter pilot. Cool. Your a buddy now. That would explain your knowledge of this hobby.

Before DJI created the Phantom they built flight controllers for helicopters. The A1 was about $10K USD. But then they introduced the Wookong H $2.5K USD and the Naza H $800 USD.

I have 2 Wookong H for my scale helis and 11 Naza H for others (F3C and 3D). You can fly them like the original Phantom with GPS locked hover. Very useful when you are at a club and flying in the same flight line as fixed wing. When they went out of production I scoured the planet and bought the last 6 I could find. I also have 2 Skookum GPS Heli FCs and 2 Align GPS controllers. At some stage I am going to attempt a follow the heli with one of my Mavics.

Here is a pic of one of my DJI Naza Helis with GPS. All ready for its calibration flight. Futaba 18MZ WC, Sbus 2 FAST Rx, Castle edge ESC with Sbus 2 telemetry adapter. Futaba GPS/ Vario sensor and Futaba Motor Temp Sensor So I get everything related to the battery in flight with voice status and warnings. Current, Mah used, Horizontal GPS ground speed, rate of climb / descent battery voltage BEC voltage even the noise on the battery voltage.

Way off topic but as you are a Heli pilot. though you may find interesting.

 

[BJR981S]

As you probably know LiPO’s tend to become less stable when fully discharged although the outcome is more likely they might simply puff up rather than perform an unscheduled rapid and spectacular deconstruction as can be the case when fully charged.

I can’t seem to locate the paper I read in temp and aging, my recollection it was from LG or Panasonic research. I did find the table from battery university which I have copied here. I did recall seeing higher numbers on the other research I read.

These numbers are for 12 months storage with the exception, where noted, if the effect of keeping a LiPO at 100% SOC at 60deg C (an unlikely event).

View attachment 50993

Thanks,

It's an interesting reference but this relates to LiCo (LiOn) batteries. The chemistry is completely different. They can be trickle charged and kept at Full charge for extended periods. Same as my LiFe Transmitter batteries in my Graupner Radios.

It would be interesting if you can find the LiPo / LiHv temp stats. I have about 200 standard LiPos I store and keep them at about 25-30 Degrees in storage. It would be good to know if I need to keep them colder.

Cheers

 

[WithTheBirds]

Thanks,

It's an interesting reference but this relates to LiCo (LiOn) batteries. The chemistry is completely different. They can be trickle charged and kept at Full charge for extended periods. Same as my LiFe Transmitter batteries in my Graupner Radios.

It would be interesting if you can find the LiPo / LiHv temp stats. I have about 200 standard LiPos I store and keep them at about 25-30 Degrees in storage. It would be good to know if I need to keep them colder.

Cheers

I will find the article. It will come to me. Im betting it was from Panasonic from memory. I use LiFePO4 prism cells for remote power, heavier for the capacity but are more robust. While the chemistry is different they are all forms of LiION. The practical recommended temp for all seems to be rated at 20 degC by the manufacturers.

 

[WithTheBirds]

Hey a fellow helicopter pilot. Cool. Your a buddy now. That would explain your knowledge of this hobby.

Before DJI created the Phantom they built flight controllers for helicopters. The A1 was about $10K USD. But then they introduced the Wookong H $2.5K USD and the Naza H $800 USD.

I have 2 Wookong H for my scale helis and 11 Naza H for others (F3C and 3D). You can fly them like the original Phantom with GPS locked hover. Very useful when you are at a club and flying in the same flight line as fixed wing. When they went out of production I scoured the planet and bought the last 6 I could find. I also have 2 Skookum GPS Heli FCs and 2 Align GPS controllers. At some stage I am going to attempt a follow the heli with one of my Mavics.

Here is a pic of one of my DJI Naza Helis with GPS. All ready for its calibration flight. Futaba 18MZ WC, Sbus 2 FAST Rx, Castle edge ESC with Sbus 2 telemetry adapter. Futaba GPS/ Vario sensor and Futaba Motor Temp Sensor So I get everything related to the battery in flight with voice status and warnings. Current, Mah used, Horizontal GPS ground speed, rate of climb / descent battery voltage BEC voltage even the noise on the battery voltage.

Way off topic but as you are a Heli pilot. though you may find interesting.

VERY Cool!!! Thanks for sharing. I got to 600 size in electrics but never got to a FBL head or GPS or any other flight assistance. My biggest investment was in tail gyros. I have nothing flying atm other than a hobbyking 450 knockoff that is a more scary than fun but I definitely will get back to it.

 

[Martin Czernik]

I find the best way to discharge a battery is to fly it until it's down below 60%. If you cant fly it, the battery will self-discharge in a number of days according to the setting you have in DJI Go.

Question: where do I find that setting in DJI GO?

 

[msinger]

Question: where do I find that setting in DJI GO?

That setting is not available for the Mavic 2. It defaults to 10 days.

 

[dekip]

Thanks Doc