Battery Question

[Zaiforce]

Hi all,

I am considering picking up a smart controller for the Mavic 2 Pro.

Just wondering one thing, with a fully charged smart controller how many Mavic 2 Pro batteries would you be able to get through on average before your controller battery is low?

If I had 4 batteries in my bird would I be able to use them all up on the one charge of the smart controller?

Thanks!

 

[WithTheBirds]

Yes.

 

[msinger]

If I had 4 batteries in my bird would I be able to use them all up on the one charge of the smart controller?

That should be doable if you're doing nothing but flying. Per the Smart Controller specs, it has a runtime of 2.5 hours.

 

[globetrotterdrone]

I have 4 batteries and the SC fully charged is able to cope with it.
I have experienced no more than 20 % with each battery (in this year's hot European summer), so 4 batteries give you enough headspace for at least 20, usually 25 % at the end.

 

[gnirtS]

I just got through 6 flights on full brightness plus some flight log upload time etc. Had about 20% remaining after that.

 

[Zaiforce]

Awesome, I am definitely picking one up then, thanks everyone.

 

[CanadaDrone]

After 3 batteries I usually have over 50% battery left on the SC. It will also depend somewhat on how bright you have the screen set, if you're also recording to an internal SD card, etc. which will affect power draw. This was also in temperatures around 0 celcius - the SC is really quite excellent.

 

[globetrotterdrone]

Just coming back from a trip, I've experienced that about 17 - 20 % seems right for the following "heavy use" scenario:

• temperature about 30 °C
• Flight time about 22 - 24 mins
• position in the shade, or half shade (20 % if standing in sun, which I try to avoid if possible)
• brightness on full (automatic)
• additional SD-card

4 batteries and some pre- and post-checks later, I ended up at about 15 %. Would be enough for another flight.

 

[Brewbud]

That brings up the question of how low will you take your controller down before recharging? Personally, I will not go below 25-30 %. Age and temperature can affect that battery curve and I don't want to risk it.

 

[WithTheBirds]

That brings up the question of how low will you take your controller down before recharging? Personally, I will not go below 25-30 %. Age and temperature can affect that battery curve and I don't want to risk it.

You mean should you be concerned that below 25-30% it may prematurely lower off?

If it is isn’t draining significantly faster from a full charge in use than the expected performance (having regard to how it was out of the box) it is unlikely to be a concern.

There is a significant difference between the potential impact of age and temperature on the performance of a drone battery and that in the the controller. Simply put it is the demand placed on the cells- your drone battery is above 2C where the controller battery is less that 1/4C. The fact that the drone demands 8 times the current from the battery provides that the effect of any age/use impact on internal resistance will be substantially mire significant. A flight battery that only provides a fraction of its rated capacity in flight might give close to the full nameplate rating powering a load at significantly lower current. There is another factor at play here also. The flight battery has series connected cells, the pack is only as good as the weakest cell and any significant imbalances in individual cell voltage will lead to it quickly collapsing under load. The controller only had a single cell so voltage balance can’t be an issue.

 

[DanMan32]

I wouldn't think using an SD card would impact battery usage.

 

[rbtmckny]

I get six flights with my Smart Controller with around 10% battery left. Sometimes a little less, sometimes a little more. You get a warning on your screen when it hits 10%.

 

[Brewbud]

You mean should you be concerned that below 25-30% it may prematurely lower off?

If it is isn’t draining significantly faster from a full charge in use than the expected performance (having regard to how it was out of the box) it is unlikely to be a concern.

There is a significant difference between the potential impact of age and temperature on the performance of a drone battery and that in the the controller. Simply put it is the demand placed on the cells- your drone battery is above 2C where the controller battery is less that 1/4C. The fact that the drone demands 8 times the current from the battery provides that the effect of any age/use impact on internal resistance will be substantially mire significant. A flight battery that only provides a fraction of its rated capacity in flight might give close to the full nameplate rating powering a load at significantly lower current. There is another factor at play here also. The flight battery has series connected cells, the pack is only as good as the weakest cell and any significant imbalances in individual cell voltage will lead to it quickly collapsing under load. The controller only had a single cell so voltage balance can’t be an issue.

I tend to agree with you for the most part. However, we designed in a single cell Lithium battery into one of our medical devices many years ago and have seen some history with this type of battery. Occasionally you will get a battery in for service where the discharge curve really sharpens. This throws the battery gauge algorithm off.

BTW - the smart controller battery is 5000 mAh @ 7.2 V. 7.2V is not a single cell. 2.5 hrs run time is a 2A draw.

 

[WithTheBirds]

I tend to agree with you for the most part. However, we designed in a single cell Lithium battery into one of our medical devices many years ago and have seen some history with this type of battery. Occasionally you will get a battery in for service where the discharge curve really sharpens. This throws the battery gauge algorithm off.

BTW - the smart controller battery is 5000 mAh @ 7.2 V. 7.2V is not a single cell. 2.5 hrs run time is a 2A draw.

Are you sure about the battery configuration? DJI specs for the M2 controller reveal 3.83V operating voltage with a battery capacity of 3950 MAh.

It wasn't that many years ago battery monitoring schemes were often fooled in the manner you describe by ageing cells. That isn't the case now where the battery monitoring SOC has moved well past simple coulomb counting- temp, voltage, average and current load, internal resistance and other factors inform the algorithm as to run time to empty and remaining capacity within 1% accuracy tolerance.

 

[Brewbud]

Are you sure about the battery configuration? DJI specs for the M2 controller reveal 3.83V operating voltage with a battery capacity of 3950 MAh.

It wasn't that many years ago battery monitoring schemes were often fooled in the manner you describe by ageing cells. That isn't the case now where the battery monitoring SOC has moved well past simple coulomb counting- temp, voltage, average and current load, internal resistance and other factors inform the algorithm as to run time to empty and remaining capacity within 1% accuracy tolerance.

I am referring to the Smart Controller. dji.com/smart-controller/specs

The supervisor IC we use is a newer one. It is just the problem of the battery curve changing to look like a cliff instead of a smooth curve for certain batteries.

 

[WithTheBirds]

I am referring to the Smart Controller. dji.com/smart-controller/specs

The supervisor IC we use is a newer one. It is just the problem of the battery curve changing to look like a cliff instead of a smooth curve for certain batteries.

There you go- my bad. I was thinking about the probable battery configuration for the M2 standard controller (I should have paid more attention to the thread title and OP).

Most of what I said still has relevance, I’m sure it has been your observation that aging LiION chemistry characteristics, particularly that of increased internal resistance, exhibit a greater limitation on actual performance at higher discharge rates. The newer BMS SOC implementations do account for changes in cell characteristics very well in my experience. If you aren’t familiar with the Texas Instruments implementations of what they call Impedence track and Gas Gauging the white papers are an interesting read. They have products certified for medical device implementation.

 

[Cpt.Barbossa1072]

 

[Thomas B]

@Cpt.Barbossa1072 ... point? A double battery setup?

 

[globetrotterdrone]

It reads 42 mins of time with this setup ...