Good battery management?

[OnlyMavic]

OK... let me see if I have a good system running here. Tell me where I might be going wrong.

I have three (3) Mavic Air 2 Intelligent Flight Battery for my lovely MA2.
I have numbered them with a Sharpie: 1, 2, and 3.
Initially, before doing any flying at all, I charged #1 to 100% with the single battery charger (not the hub).
I flew #1 to about 45% and came home.
I set #1 aside in a cool dry place.
For next flight, I charged #2 to 100% the same way.
I flew #2 to about 50% and came home.
I set #2 aside in a cool dry place.
I repeated the above steps for battery #3.
When I was ready to fly for the fourth time, I re-charged battery #1 to 100%, and flew it immediately.
I flew #1 to about 55% and came home.

Following this management scheme, will I be getting the maximum life out of these three batteries? Or is there something else I could be doing to extend their life even further?

TIA for your input!

 

[sloopjonb]

That seems like a good schedule but don't stress yourself out about it. The drone uses smart batteries so it will reduce its charge to 96% after 24 hours and then 60% after 5 days to preserve the battery cells.

 

[OnlyMavic]

That seems like a good schedule but don't stress yourself out about it. The drone uses smart batteries so it will reduce its charge to 96% after 24 hours and then 60% after 5 days to preserve the battery cells.

Oh, really?! If I keep a 100% charged battery un-flown for 5 days, it will intelligently reduce its charge level to 60%, on its own? I did not know that. I had gleaned from here and elsewhere that best practice was to charge a battery from a storage level of 50-60% up to 100% just prior to flight, and that discharge through flight use was the best way to discharge the battery back down to storage levels. I was reading somewhere that storing a 100% charged battery without using it was a good way to reduce its effective lifespan.

 

[itsneedtokno]

I fly from 100% to 10-30%
Leave them off charge for a couple hours then charge all three, will definitely fly one (if only for sunset) two will be in the morning (likely for sunrise) and three will be a "maybe later" but will at least be used for sunset (weather permitting, i don't have a wetsuit yet, so i cant fly confidently in the rain).

I work four 15 hour days. when i work i only charge one battery a day (cycling them).

I have flown over 150 flights since May 25th. my batteries seem to be in good shape.

happy flying!

 

[dawgpilot]

Oh, really?! If I keep a 100% charged battery un-flown for 5 days, it will intelligently reduce its charge level to 60%, on its own? I did not know that. I had gleaned from here and elsewhere that best practice was to charge a battery from a storage level of 50-60% up to 100% just prior to flight, and that discharge through flight use was the best way to discharge the battery back down to storage levels. I was reading somewhere that storing a 100% charged battery without using it was a good way to reduce its effective lifespan.

It's explained more in the user manual, but you are right that you should minimize the time the batteries are around 100 percent if you can. The self-discharge will still result with a fully charged battery sitting at 96 percent for nearly 5 days otherwise.

I either fly my drone until the batteries are at 50-60 percent, or use the USB adapter to charge some of my other electronics to lower the level.

 

[itsneedtokno]

I either fly my drone until the batteries are at 50-60 percent, or use the USB adapter to charge some of my other electronics to lower the level.

i love this idea... i never thought id see a use for the adapter

 

[OnlyMavic]

I either fly my drone until the batteries are at 50-60 percent, or use the USB adapter to charge some of my other electronics to lower the level.

Ahh, I like that idea. If I have a 100% battery, and no plans to fly soon, then I should drop it onto the Power Bank Adaptor and charge something else with it. Good tactic.

I also note that the User Manual states:
• It is recommended to discharge the Intelligent Flight Batteries to 30% or lower. This can be done by flying the aircraft outdoors until there is less than 30% charge left.

So, the best non-flight storage level seems to be 30% or lower. I'll happily fly my aircraft until the battery charge is at 25%, and then take it back up to 100% just prior to flight.

 

[dawgpilot]

Ahh, I like that idea. If I have a 100% battery, and no plans to fly soon, then I should drop it onto the Power Bank Adaptor and charge something else with it. Good tactic.

I also note that the User Manual states:
• It is recommended to discharge the Intelligent Flight Batteries to 30% or lower. This can be done by flying the aircraft outdoors until there is less than 30% charge left.

So, the best non-flight storage level seems to be 30% or lower. I'll happily fly my aircraft until the battery charge is at 25%, and then take it back up to 100% just prior to flight.

I noticed that 30 percent level mentioned in the manual too. I'm not quite sure why they would only self discharge to 60 percent then... only DJI knows why they do what they do, I guess.

 

[E90RAW]

OK... let me see if I have a good system running here. Tell me where I might be going wrong.

I have three (3) Mavic Air 2 Intelligent Flight Battery for my lovely MA2.
I have numbered them with a Sharpie: 1, 2, and 3.
Initially, before doing any flying at all, I charged #1 to 100% with the single battery charger (not the hub).
I flew #1 to about 45% and came home.
I set #1 aside in a cool dry place.
For next flight, I charged #2 to 100% the same way.
I flew #2 to about 50% and came home.
I set #2 aside in a cool dry place.
I repeated the above steps for battery #3.
When I was ready to fly for the fourth time, I re-charged battery #1 to 100%, and flew it immediately.
I flew #1 to about 55% and came home.

Following this management scheme, will I be getting the maximum life out of these three batteries? Or is there something else I could be doing to extend their life even further?

TIA for your input!

I have a particular interest in battery technology and have a couple posts on this site. Its good to see another OCD pilot on board. Numbering is good for you but the batteries will tell you how many cycles they have on them if you mix it up. Quick overview:
1. LiPo are finicky animals. You should not discharge them to below 3 volts/cell whether during flight or maintenance. The "HUB" will not over charge them and will turn off once capacity is reached. Capacity cannot be measured so it is some number of volts, likely 4 or 5/cell.
2. Forget about %battery remaining and instead focus on volts and temperature during flight. Generally do not go below 3.3 volts/cell or 55 degrees Celsius. You should be checking periodically just like an airplane pilot would check fuel gauge and consumption. DJI has pretty conservative algorithms and so it would be difficult to go that low, but it can happen.
3. The hub will NOT charge the battery if it is hot as a protective mechanism. Do NOT charge when battery is hot which you are doing.(I recommend the hub strongly as it protects the batteries).
4. Unfortunately LiPo's are good for between 150-250 cycles of charging, as opposed to NiMH which are good for 1000 cycles. Discharging to below 3 volts/cell or high temperatures will cause lithium oxide formation and eventual early failure. I get worried when the batts are above 50 degrees Celsius. In addition LiPo's are prone to conflagration with excessive Li2O formation.(NiMH do not conflagrate).
5. The problem with all batteries is that we really don't know what their capacity is(especially DJI batteries), ie, we don't know how full they are. So we rely on proxy's such as volts, which approximates pretty closely. In the RC industry capacity is measured in Milliamp hours, but with DJI products we don't know this number.
I hope that helps you make appropriate decisions.

 

[Airmaxx23]

I have a particular interest in battery technology and have a couple posts on this site. Its good to see another OCD pilot on board. Numbering is good for you but the batteries will tell you how many cycles they have on them if you mix it up. Quick overview:
1. LiPo are finicky animals. You should not discharge them to below 3 volts/cell whether during flight or maintenance. The "HUB" will not over charge them and will turn off once capacity is reached. Capacity cannot be measured so it is some number of volts, likely 4 or 5/cell.
2. Forget about %battery remaining and instead focus on volts and temperature during flight. Generally do not go below 3.3 volts/cell or 55 degrees Celsius. You should be checking periodically just like an airplane pilot would check fuel gauge and consumption. DJI has pretty conservative algorithms and so it would be difficult to go that low, but it can happen.
3. The hub will NOT charge the battery if it is hot as a protective mechanism. Do NOT charge when battery is hot which you are doing.(I recommend the hub strongly as it protects the batteries).
4. Unfortunately LiPo's are good for between 150-250 cycles of charging, as opposed to NiMH which are good for 1000 cycles. Discharging to below 3 volts/cell or high temperatures will cause lithium oxide formation and eventual early failure. I get worried when the batts are above 50 degrees Celsius. In addition LiPo's are prone to conflagration with excessive Li2O formation.(NiMH do not conflagrate).
5. The problem with all batteries is that we really don't know what their capacity is(especially DJI batteries), ie, we don't know how full they are. So we rely on proxy's such as volts, which approximates pretty closely. In the RC industry capacity is measured in Milliamp hours, but with DJI products we don't know this number.
I hope that helps you make appropriate decisions.

The DJI packs for the Air 2 are listed as 3500mAh but we have no way of knowing how many mAh we've used during a flight or put back into the pack when charging.

 

[E90RAW]

The DJI packs for the Air 2 are listed as 3500mAh but we have no way of knowing how many mAh we've used during a flight or put back into the pack when charging.

This is why they use volts which is a pretty close approximation to capacity. Once the volts start dropping off you know the capacity(tank) is low. Also the temp starts going up as internal resistance starts going up as volts go down. Another good thing to watch. The capacity would be calculable(is that a word?) if we knew the speed of the motor and discharge rating and internal resistance. The motors are usually(in RC world) rated as 3500Kv or 3500RPM/volt delivered. I have a felling that drones are much higher. But ostensible you divide the mAmps by the RPM/volt to get an approximate number. The discharge rating is how fast the battery lets the energy out without damaging itself, That is like a speed re stricter on a golf cart. That would be in the equation as well. With RC cars you can actually calculate the number but with airplanes/drones no one wants to trust the consumer with a bad calculation.

 

[E90RAW]

Ahh, I like that idea. If I have a 100% battery, and no plans to fly soon, then I should drop it onto the Power Bank Adaptor and charge something else with it. Good tactic.

I also note that the User Manual states:
• It is recommended to discharge the Intelligent Flight Batteries to 30% or lower. This can be done by flying the aircraft outdoors until there is less than 30% charge left.

So, the best non-flight storage level seems to be 30% or lower. I'll happily fly my aircraft until the battery charge is at 25%, and then take it back up to 100% just prior to flight.

read below

 

[Airmaxx23]

This is why they use volts which is a pretty close approximation to capacity. Once the volts start dropping off you know the capacity(tank) is low. Also the temp starts going up as internal resistance starts going up as volts go down. Another good thing to watch. The capacity would be calculable(is that a word?) if we knew the speed of the motor and discharge rating and internal resistance. The motors are usually(in RC world) rated as 3500Kv or 3500RPM/volt delivered. I have a felling that drones are much higher. But ostensible you divide the mAmps by the RPM/volt to get an approximate number. The discharge rating is how fast the battery lets the energy out without damaging itself, That is like a speed re stricter on a golf cart. That would be in the equation as well. With RC cars you can actually calculate the number but with airplanes/drones no one wants to trust the consumer with a bad calculation.

That's one of the things I like about the quads I build that use BetaFlight, you can setup mAh consumption to more closely monitor your packs. It has to be calibrated but then it's accurate to within a few mAh as far as what the quad used and what the charger puts back into the pack.

 

[Airmaxx23]

read below

I don't know where they're coming up with 30% as a storage voltage. LiPo packs should be stored at 3.85v/cell.

 

[E90RAW]

I don't know where they're coming up with 30% as a storage voltage. LiPo packs should be stored at 3.85v/cell.

You are absolutely correct. A LiPo should never be allowed to go below 3 volts storage or flight time, and conservatively higher. Once below 3 volts they are rarely recoverable. 3.85 is probable the nominal value(the average so to speak) and you can store below that. Forget the %, a useless number.

 

[OnlyMavic]

One quick direct response now, and then more later...

Do NOT charge when battery is hot which you are doing.

I am not doing that. As I described, I am taking the battery from my aircraft after a flight and setting aside to cool. I never charge a battery while it still feels even slightly warm to the touch. In my three battery rotation and my current flight schedule, the battery that just flew won't fly again until the next day. Plenty of time to cool, and then get recharged for another flight.

 

[OnlyMavic]

To get to the nut of it...

Forget the %, a useless number.

Got it. Will do. Percentage is dead to me now. I will pay more attention to voltages and temperature. If I see the voltage hit 3.3V or the temp hit 50C, I'm coming home. I just wish there was a way to switch the readout for battery info on the main flight screen of the DJI Fly app over to voltage and temperature, instead of percentage and flight time. We have to keep tapping that battery info icon up there to see the voltage and temp. Kind of distracting to have to do that.

The "HUB" will not over charge them and will turn off once capacity is reached.

I'm finding the hub charger unnecessary. According to my flight schedule, I don't have a burning need to charge up more than one battery at a time. Why bother with the hub charger at all?

 

[DavidT_ NZ]

OK... let me see if I have a good system running here. Tell me where I might be going wrong.

I have three (3) Mavic Air 2 Intelligent Flight Battery for my lovely MA2.
I have numbered them with a Sharpie: 1, 2, and 3.
Initially, before doing any flying at all, I charged #1 to 100% with the single battery charger (not the hub).
I flew #1 to about 45% and came home.
I set #1 aside in a cool dry place.
For next flight, I charged #2 to 100% the same way.
I flew #2 to about 50% and came home.
I set #2 aside in a cool dry place.
I repeated the above steps for battery #3.
When I was ready to fly for the fourth time, I re-charged battery #1 to 100%, and flew it immediately.
I flew #1 to about 55% and came home.

Following this management scheme, will I be getting the maximum life out of these three batteries? Or is there something else I could be doing to extend their life even further?

TIA for your input!

I do the same with the same kit but tend to fly close to Home for the end of flight and I run the batteries down to about 10% before landing. One advantage of the Air 2 is its extra flying time. If you have it, why not use it? ??

 

[PimV]

To judge the (remaining) charge from the voltage with any battery has always been a tricky business (with some battery systems more, with some less). Therefore IC-manufacturers all the time design better and more accurate battery-management Ic's, which don't only use the voltage of the cells but also the amount of current going in and out and the temperature. DJI calls these batteries "Intelligent Flight Batteries", so I think it is fair to assume they have incorporated these modern battery-management IC's in their design. Therefore I am inclined to letting the system do the job and not to spoil my flying pleasure, by checking battery voltages and temperatures all the time. That time can better be spend to wacht the safety of the flight and to make nice photo's and video's.

 

[OnlyMavic]

That time can better be spend to [watch] the safety of the flight and to make nice photo's and video's.

Quite agree. But... these Intelligent Flight Batteries are an investment, just like everything else that goes into become a drone pilot. One wants to get a higher return on investment, if one can do anything at all about it. I want to be just as smart as these batteries think they are, and not do stupid, careless things that diminish their useful lifespan, and force me to buy new ones sooner than I might otherwise have to. Much can be said about the ability of these batteries to manage themselves. But that only goes so far. Beyond their abilities lies our ability to care for them. I just want to be sure I'm doing the right things. A grain of obsessiveness can yield a pound of pleasure.