DJI Battery Cycles; Definition

[meierjn]

I have a DJI Mini 3 Fly more combo that came with 3 batteries. I cycle between batteries after every flight. I like to top-up the batteries before heading out even if they have only been sitting unused for a few days. This got me curious with what is the DJI definition of a battery cycle? I see in the controller that each battery cycle is counted but is a count every time it is charged or does the battery have to be below a certain point to be recorded as a battery cycle? I'd like to maximize each batteries lifespan so would like to try and keep each batteries cycle count close.

Thanks in advance!

 

[mark.pinskey]

I have a DJI Mini 3 Fly more combo that came with 3 batteries. I cycle between batteries after every flight. I like to top-up the batteries before heading out even if they have only been sitting unused for a few days. This got me curious with what is the DJI definition of a battery cycle? I see in the controller that each battery cycle is counted but is a count every time it is charged or does the battery have to be below a certain point to be recorded as a battery cycle? I'd like to maximize each batteries lifespan so would like to try and keep each batteries cycle count close.

Thanks in advance!

I will watch for answers as I always wondered about this myself. Thanks for asking the question….

 

[Felix le Chat]

With my mini 3 pro, I've noticed that after three or four days idle, the batteries are still showing 4 lights and if linked to the charger, will start to 'top up' whatever nominal charge has been lost, so an *estimate* would be that the charge has to drop to 82% and below before the BMS frees the battery to accept charge.

**ADDENDUM**
A little bit of experimentation tells me that batteries left in the charging block will self discharge more slowly than a battery housed in the drone. Drone battery showed four lights in-drone, but was down to 82% according to the FLY app.

When fitted in the charger, it still showed four lights, but began a top up charge cycle. The two in the charging block (charged at the same time as the third) showed 96% after 3 days storage and did not start to charge.

 

[moldorf]

as I understand it, a battery cycle is a re-charge after the battery has been discharged to a depth of 80%. But that's really an estimated discharge

"Life (in cycles) = (Capacity x 100) / (Discharge rate x Depth of discharge)

In this formula, capacity is the rated capacity of the battery in amp-hours (Ah), discharge rate is the rate at which the battery is discharged in amperes (A), and depth of discharge is the percentage of the battery’s capacity that is used before recharging."

how to estimate li-ion battery life – Mission Engineering

for me, if I don't fly for a month or so, I won't recharge batteries until the day(s) before I intend to fly. I have 5 Mavic 3 batteries. At an average of 300 cycles/battery, that's a theoretical cycle capacity of 1500. Obviously, the practical cycle capacity will be less, but with caution and care, not a lot less.

 

[waynorth]

Here is what DJI says about battery cycle:
"A battery cycle count is not the times that you charge a battery, but simply refers to the times that the battery consumption accumulates to 75% of the battery capacity. When the battery cycle count is over 200 times, battery performance will decline. In this case, it is recommended to replace the battery with a new one."

 

[meierjn]

Here is what DJI says about battery cycle:
"A battery cycle count is not the times that you charge a battery, but simply refers to the times that the battery consumption accumulates to 75% of the battery capacity. When the battery cycle count is over 200 times, battery performance will decline. In this case, it is recommended to replace the battery with a new one."

So, if I am understanding correctly a battery cycle will be registered if the battery is charged when depleted to 25% capacity or lower? Topping it up or charging at anything above 25% will not register as a charge cycle?

 

[FLDave]

So, if I am understanding correctly a battery cycle will be registered if the battery is charged when depleted to 25% capacity or lower? Topping it up or charging at anything above 25% will not register as a charge cycle?

Not correct. Read the DJI definition again.

 

[moldorf]

So, if I am understanding correctly a battery cycle will be registered if the battery is charged when depleted to 25% capacity or lower? Topping it up or charging at anything above 25% will not register as a charge cycle?

I might be wrong, but the way I read it, a cycle starts when the battery drops to 75% of capacity, or lower, and then is re-charged; that would be one cycle

it's probably safe to say that almost all drone flights will create 1 cycle for the battery used

 

[FLDave]

Each time total charge consumption equals 75 of total charge it is a cycle. Total consumption is what counts. So, if the battery charge drops to 50% and you charge only to 75% that is 25%; the the next time it drops to 50% you charge to 100% that is a 50% consumption amount; adding the 2 together is 75%: 1 cycle count for
DJI. If it drops to 25% and you change to 100%, that is 1 cycle count. If you charge at 75% up to 100% for 3 times, that will be the 75% total consumption for a single cycle count.

 

[3rdof5]

I have been flying DJI drones since the Phantom 2. The consensus since day 1 is that a battery cycle is equal to a full charge cycle from depleted to full. Meaning, if you discharge your battery to 50% and charge it fully twice, it will count up 1 cycle.
All batteries have a limited amount of charge cycles before they start to degrade. There is no advantage or need to cycle your DJI batteries. Best practice is to never store them below 50% charge, charge them fully after use (and after they have cooled) and let the autodischarge function do it's job and you will have no issues and best life. And never start a fresh flight with a partially charged battery.

 

[meierjn]

Thank you all for the explanations!

 

[Droning on and on...]

And never start a fresh flight with a partially charged battery.

Why? The only issue is a shorter flight.

 

[quaddamage]

DJI has its own definition? That's surprising, considering they use chips based on SBS Specification.

The SBS Specification is public:

Smart Battery Data Specification
SBS Implementers Forum -Page 32- Revision 1.1

5.1.22. CycleCount() (0x17)
Description:
Returns the number of cycles the battery has experienced. A cycle is defined as:
An amount of discharge approximately equal to the value of DesignCapacity.
Purpose:
The CycleCount() function provides a means to determine their battery's wear. It may be used to give
advanced warning that the battery is nearing its end of life. The CycleCount returned value multiplied by
the DesignCapacity value can give an approximate “odometer” reading for the total capacity delivered by
the Smart Battery.
SMBus Protocol: Read Word
Output: unsigned int -- count of charge/discharge cycles the battery has experienced
Units: cycle
Range: 0 to 65,534 cycles
65,535 indicates battery has experienced 65,535 or more
cycles.
Granularity: 1 cycle
Accuracy: absolute count

The TI BQ-series chips which DJI uses do expand on that definition, introducing Cycle Count Percentage and Cycle Capacity Type:

The value of CycleCount() increments when an accumulated discharge is more than Cycle Count Percentage of
FullChargeCapacity() (if [CCT] = 1) or Design Capacity (if [CCT] = 0).

So I guess what DJI did was to just set the "Cycle Count Percentage" to 75, in a solution previously prepared by western companies.

 

[3rdof5]

Why? The only issue is a shorter flight.

That's not the only issue, I have seen instances where the reported battery level in the app is higher than what is actually available in the battery leading to a sudden and unexpected low voltage situation. Starting a fresh new flight with a full battery eliminates this issue. I haven't seen this problem if you start full, land at 70% for example, shut down and swap an sd card, and then take off again, but that's not technically a new fresh flight.

 

[Droning on and on...]

That's not the only issue, I have seen instances where the reported battery level in the app is higher than what is actually available in the battery leading to a sudden and unexpected low voltage situation. Starting a fresh new flight with a full battery eliminates this issue. I haven't seen this problem if you start full, land at 70% for example, shut down and swap an sd card, and then take off again, but that's not technically a new fresh flight.

Good point... I wasn't including long-dormant batteries in my thinking.

 

[riterb97]

This what DJI admin Natalia said regarding the Battery definition: Hi there, thank you for reaching out. The battery cycle is typically considered a full discharge and recharge of a battery. However for the Li-ion 4s in Air 3, it will be counted once when the battery level is 75% consumed of the capacity mentioned in the official manual, including consumption by the battery’s self-discharge. To check the capacity, you may refer to the " specifications" in User Manual.

The tests that I have done on the Air 3 batteries prove otherwise. My Cycles go hand in hand with the AMOUNT OF RECHARGING, irrespective of the % discharge. I received my % discharge from Airdata UAV (Unless they are at fault, which I doubt) and according to the LED'son the battery.

A 2 will mean 2 LED's on, A 2+ means 2 on + 1 flashing

Batt No1 Discharge values
67% ; LED 2+; Recharged 3x; Cycle count 3
34%; LED 1+; Recharged 4x; Cycle Count 4
43%; LED 2; Recharged 5x; Cycle Count 5

Batt No2 Discharge values
23% ; LED 1; Recharged 3x; Cycle count 3
55%; LED 2+; Recharged 4x; Cycle Count 4
34%; LED 1+; Recharged 5x; Cycle Count 5
94% LED 4; Recharged 6x; Cycle Count 5

The above indicates to me that to keep the cycle count as low as possible, I should deplete my batteries as low as possible- which of course do not make sense! I get no further proper answer from DJI on this!!