OK, so I have brought this up in other contexts, but you have not responded, and today was really enough, I'm done, its over., it never worked, we're through..........

Four 5" freestyle quads.  ONE has vastly inferior flight time to the other three, and I DO mean vast. The culprit struggles to fly for 4 minutes, even flown around gently with no aero moves.  Today it was managing a miserly pathetic at best 3m 45s of very unsatisfactory dull performance.  The best of the four quads was today managing over 8 minutes of spirited freestyle aero, power loops, reversals, etc. And the other two were 6-7 minutes. 

Its done this from new, NOTHING I have tried has made it noticeably worse or better.  Its capable of flying like the others, but then the duration is under two minutes. Does it think its a ruddy brushed motor Inductrix??  

Its not battery related. Proven.
Its the same on matching 4S or 6S to the others.
Its not weight related. Proven.
Its not prop related (or at least alterable by changing). Proven.

VTX is set to the same power draw (all on Vista, same settings)

I'd be up for changing motors or ECB board if I had ANY confidence it would be worth it, but I haven't. Yes, this is the highly rated Nazgul Evoque  DJI with FrSky.

This is SO frustrating!!

I kind of have the inverse of that problem with my main 5" quads but always assumed it was the FPVCycle 25mm motors that were eating the battery. On the flip side my Nazgul v2 can nearly pull double the time. Pretty sure they used a different motor than the evoque. They say Xing-E 1800kv

To be fair I've not done scientific tests with them and I'm pretty sure I don't fly the Nazgul as hard for whatever reason. Like I have a tendency to fly smoother with the Nazgul and harder with the AOS which has a little bit more aggressive camera angle.

The Evoque is sold with unmarked motors so its not certain WHAT they put on it!

From what I can find on the google, the evoque has:
Xing2 2207 motors, in either 2750kv (if 4s version) or 1750kv (if 6s version).

I’m assuming you have the 6s version since you said you’ve tried 6s on it.

Given everything you’ve ruled out, I’d say it’s the motors being ridiculously power hungry.
I couldn’t find a motor datasheet (I didn’t try too hard), but iFlight says peak current is 36.3A / 46.05A.

Something like the RCinPower Bison 22.5-7 1800kv pulls significantly less current (25A max), but they are 2.5g heavier so maybe there’s a better option.
https://pyrodrone.com/collections/22xx/p...-gun-metal

Edit- you’re an experienced builder and flyer so I’m assuming you’ve already done this, but just in case- make sure you’ve calibrated your voltage sensor in betaflight so that you’re not landing before you need to.

Thanks, yes. They chose not to mark them on the Evoque though, so I was suspicious that as this was made at the height of the initial COVID induced shortages that they'd just slapped any old motors on it. It's "supposed" to be a 4S version. But runs 4S and 6S with no changes whatsoever with equal disappointment in terms of flight time. The fact its perfectly happy on 6S unaltered suggests I am right, its a 6S set up sold as a 4S. Except, neither alters its poor duration to any noticable effect.

Flown as I want to (smooth freestyle) its flight ability is OK but duration is rubbish. 2 mins something is IMO unacceptable when the similar weight GEPRC Mk5 goes at LEAST two minutes more, even when hammered.

I have used in 4S - 1350, 1500, 1550, 1700, and 1800. And in 6S - 1350, 1550. So not pack weight. Nor 4S/6S.

I keep thinking there might be a filter or other setting that could help...............

Running a couple of older "test" packs I no longer care much about, but are still good for duration on other quads, I have tried, as well as my normal 3.5v at landing, running it to 3.0v per cell, and on landing checking the pack with a couple of BATTGO's, and the packs have recovered voltage to a level you'd expect from those packs, what they do on other quads, so even ignoring the on quad feedback, its desperately short on duration when compared. (and that makes the quad indication about right) Good thought, but the packs are genuinely "done".

Its so frustrating as it handles well, I actually like the Polar Starlight camera even in sunny daylight, and overall its very well made.

SO many times recently I have hovered over the key to order some motors, but that's £80 which could easily be wasted if no change. I do have a set of BBB-R race 4S motors that I removed from a now defunct quad way back as they were SO current hungry and frankly too powerful (!), so maybe I should bite the bullet and fit them, they have short wiring as they were arm ESCs, and so the work needed (even to remove the side shielding and get near the ESC board terminals) is high and it seems unlikely they, as already cell sucking monsters, would help!!

What I could do with is people with a Evoque 4S and a 6S they are happy with to supply their dump files for me to try. In fact, I'll ask in a clearly worded title for that directly in another thread!

You’ve got these blacked out motors, yeah?
https://shop.iflight-rc.com/motors-cat88...F5-pro1610

4s or 6s, those motors suck amperage like a MF-er.

Total average amp draw has a direct impact on flight time- that average can be hover time, 3/4 throttle, whatever- the more current your quad is sucking, the less flight time you’re gonna have if your constant is the same battery (same cell count, same capacity, same c rating- same battery.)

If you don’t wanna buy a new thing- try putting the motors from one of your 3 other 5” quads onto this bird and see if it makes a difference in flight time- I’d be willing to bet that it will.

There’s not a setting in betaflight that will fix it. Someone else’s dump or diff won’t fix it.

It being able to run on 6s when it was sold as a 4s just means the esc is overrated- that’s a good thing, it also means that they overbuilt/underrated the motors, which is also a good thing- but that has more to do with the gauge of magnet wire they used in the motor. None of this stops or reduces the amperage these motors will pull- being overbuilt means they’re less likely to burn out, but, based on their specs, they’re clearly less efficient.

I wouldn’t bother fitting those spare current hungry motors- that’s the opposite of what you want if you’re trying to increase flight time. Try fitting a set of motors from one of your 5” quads that get an acceptable flight time.

Ooooh No, I really don't want to play with what I have that works well!  

OK, given that the GEPRC Mk5 BNF I have is roughly the same weight, and manages consistently way WAY more flight time for the same level of aggression flying, easily more than double, it seemed only logical that if I WAS going to splash the cash on motors it'd be for more of them as a known quantity. They are GEPRC (of course) SpeedX2 1960kV 2107.5.

NO suppliers popped up for UK stock (damn) ,  so have ordered GEPRC direct.  I bought the Mk5 ELRS/DJI direct from them and it arrived in a much shorter time than they stated likely, so I hope that response time follows for these.

At the very least I'll have spares for the Mk5, right?  

As I'm going to have to heavily dismantle the Evoque to get near the motor connections, I'll admit I will be tempted to leave the ineffective as lighting LED side plates off, but should not as that would be changing two things at once, and ATM the one thing the Evoque does have going for it is its better water droplet protection from prop spin off and landing contact when the grass is wet (this IS the UK, and even when its not been raining, we get lots of very dew laden grass in the mornings!!!)

There will now be a (shipping) intermission.

Cool beans.

Yeah, probably best to not mess with what works.

Let us know how it goes whenever they arrive.