Is it most battery efficient to fly as fast as possible?

[WithTheBirds]

From 20% you have a lot of range left. Fly by voltage after 0% and land it around 3.5v.

Don’t expect to get anywhere near typical service life from your batteries if you fly them dry with any regularity.

 

[parkgt]

I always wondered if the RTH speed was not this magic figure. Why else would they choose that specific speed?

 

[Meta4]

I always wondered if the RTH speed was not this magic figure. Why else would they choose that specific speed?

RTH speed is quite a bit slower than the optimum speed for greatest distance.
It's also too slow to help much if you have to RTH against a decent headwind.
There's no good explanation for DJI's choice of a slow RTH speed.

 

[RayOZ]

From 20% you have a lot of range left. Fly by voltage after 0% and land it around 3.5v.

My old MP batteries % drops really quickly once it’s below 15%. Even while hovering. I wouldn’t risk my drone being to far away from me when it’s below 20%.

 

[WithTheBirds]

RTH speed is quite a bit slower than the optimum speed for greatest distance.
It's also too slow to help much if you have to RTH against a decent headwind.
There's no good explanation for DJI's choice of a slow RTH speed.

Isn’t RTH ground speed- that is tilt angle will continue to increase to maximum if required in an effort to fight the wind? The few occasions I have had a RTH kick in (lost signal) I have taken over as soon as connection was re-established so haven’t noticed.

 

[DanMan32]

I believe the attack angle is limited, particularly since it's based on P mode limits.

 

[WithTheBirds]

I believe the attack angle is limited, particularly since it's based on P mode limits.

Yes- I should have been clearer (there will be tilt limits set in the FC obviously). Allow me to rephrase- in RTH mode the mavic will maintain speed up to the point max airspeed is reached (that might well be P mode max). The point is it will attempt to fight the wind.

 

[DanMan32]

Anyone with access to a wind tunnel that doesn't block GPS?

 

[MaxHam]

At 50deg C cycle life is around half what you might expect at 20deg C. The battery will deliver good power though.

I found out that it's the other way around (or maybe I understand your term cycle life wrong) - and by far not so extreme:
The lower the cell temperatures of the battery the higher the internal resistance. Through that resistance energy is turned into heat = capacity loss.
See graph below. I asked some specialist who sent me this.

It makes sense. The max. distance according to the manual is 18km at full power (higher battery temp) in P-GPS.
All my trials at slower speeds were for nothing. ?
On my last trial I went out 9.03km at full power before I got scared and turned around at 59%. I landed at 7%.

I think I'm done with this now. Don't want to run a battery to 0%.

 

[WithTheBirds]

I found out that it's the other way around (or maybe I understand your term cycle life wrong) - and by far not so extreme:
The lower the cell temperatures of the battery the higher the internal resistance. Through that resistance energy is turned into heat = capacity loss.
See graph below. I asked some specialist who sent me this.

It makes sense. The max. distance according to the manual is 18km at full power (higher battery temp) in P-GPS.
All my trials at slower speeds were for nothing. ?
On my last trial I went out 9.03km at full power before I got scared and turned around at 59%. I landed at 7%.

I think I'm done with this now. Don't want to run a battery to 0%.

View attachment 86019

You understood wrong- by cycle life I mean reduce in usable capacity/number of charge/discharge cycles before the pack is retired.

As far as power delivery LiPO's love heat.

 

[paulatkin73]

to the topic - unless i forgot it completely - from what i recall of how to get the best distance in the practical way - you do it by setting degree of attack param to 42 deg and use ATTI mode to prevent any kind of course correction. that will drain battery at 8A-12A rate and should be optimal for covering long distances.

you can experiment easily setting higher angles for S mode and then look at the .dat log file on the ESC channels to see the current data and total current from the battery. above of 15A it drains battery and sags voltage pretty bad on those lipos - they have a pretty dismal C rating, IMHO. like, 10C top. or less, based on the way they behave and heat up.

 

[paulatkin73]

I believe the attack angle is limited, particularly since it's based on P mode limits.

you can set it to anything you want, why? every mode has its own param for this setting.