Quad lifts off and lands (crashes) immediatly [solved: was bad battery]

ArduCopter Copter 4.0
1

Hi, I’m quite a newbie so please forgive errors and inaccuracies.

In a few words, the problem is that my Quad lifts off 1m /1,5m at full throttle and after seconds lands/crashes.

…with more detail:

During setup, I followed carefully and exactly the steps described in Arducopter documentation, how to’s videos and did ESC calibration many times… but the result was always the same, little take-off and then a crash, like if the Quad were too heavy for the provided motors/propellers.

I repeat: it lifts off 1.5 meters only at full throttle.

I tried to look in this forum for similar problems as well but without success. Also, the collected logs look still a little unfamiliar to me. :slightly_frowning_face:

I’m asking for hints, controls to do, suggestions or whatever I have to do in this case to troubleshoot this problem and let this Quad fly :slight_smile:

to give you more specs

Thank you in advance for any help.

Francesco

2

Please collect and provide logs :slightly_smiling_face:
Here is details about: https://ardupilot.org/copter/docs/common-downloading-and-analyzing-data-logs-in-mission-planner.html

3

Thanks!

Here are the .bin files of 3 yesterday crashes… I can provide the .log too if needed or better…

https://drive.google.com/file/d/1zVDuRag1ywwDJr-kDCCgOw8puYc2qFBx/view?usp=sharing

https://drive.google.com/file/d/1rDRGytjTJMks2mhoWH3P7X-M8u5eKEZR/view?usp=sharing

https://drive.google.com/file/d/15uTgb8YNZaAA0dKLHKZxkP4c0JwPBysa/view?usp=sharing

F.

4

@Francesco_S Sir,
1.PSC_ACCZ_P=0.4( * PSC_ACCZ_I to 2 x MOT_THST_HOVER)
2.PSC_ACCZ_I=0.8 ( * PSC_ACCZ_P to MOT_THST_HOVER)
Make this change and do the test again Sir.
Source is https://ardupilot.org/copter/docs/tuning-process-instructions.html#test-althold

Thanks and regards
Mohan

5

Your motors are commanded to Max, battery voltage sags to <2.8V/cell and it’s not flying. Over loaded/ Under powered.

Rcout
Rcout1699×601 84.5 KB

What motors, props and Take Off Weight?

6

Thank you!

I’ll try it out and come back!

F.

7

Here are the specs:

  • Motors - 2216 KV880（ V2 Update）
  • Propeller 1045（ V2 Update）
  • Take Off Weight 1400g (battery included)

Thanks!

8

That should get off the ground but it will be underpowered. Or your weight estimate is off. It’s a HolyBro kit? They say it weights 1320g w/o a battery. Anyway it’s underpowered, no amount of parameter fiddling will fix the basic problem. Buy a 4S battery that will bring the Take Off Weight to ~1700g and you should be good,

9

Thank you Dave,

I weighed the Quad by myself right now, it is equipped with a 4S/5000mAh/50C battery and confirm that it weight is 1430g battery included (503g)

F.

10

OK, then you have a battery problem if it’s a 4S battery or your battery monitoring is way off. Look at the battery voltage in your logs. They start ~11V (2.75 V/Cell for 4s) and drops to ~8.5V (2.1 V/cell or dead) under load. Was the battery supposed to be fully charged when these logs started?

11

@dkemxr probably voltage divider is wrong? but anyways sag is tooooo big

12

When I started battery was around 14,5 V :thinking: … effectively I’ve to investigate in that direction!

Thanks

13

Well, it would be a good idea to start with a fully charged battery…

1 Like
14

The voltage multiplier is at the default value (18.182) for a Pixhawk 4 so not sure.

15

Voltage Divider seems correct… (18.182)

for “sag” you mean the potential difference (10.5 -> 8.5) during the throttle increase? (sorry I’m not native english)

effectively everything seems going toward a battery failure…

16

Yes. 10.5V is already way too low for a 4S battery and the sag is in dead territory. This is why I assumed you were on 3S. So yes, I would suspect the battery as well.

1 Like
17

dkemxr is 100% correct. You have a SERIOUS problem with that battery.

18

battery changed… everything flies as it should :star_struck: :pray:

Thank you all