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Apr 24, 2019, 10:50 AM
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Bob AZ's Avatar
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Discussion

What's wrong with this picture?


I recently got back to flying copters after a work related hiatus of 4 years. I have an ammo can full of batteries stored at storage charge and an F450 quad and F550 hex plus an unfinished tarot 680 hex. I also have a box of new motors, Sunnysky 2212 980KV and T-Motor 2212 920kv, and and another box full of 1045 Gemfan props.

I recently completed the 680 using the T-motors and 1045s and also a new Tarot 650 quad using the Sunnyskys and the 1045 props. I know these are not the ideal motors and props but I though I'd at least get a couple of usable copters. AUW is 1250gm (With battery)

New to the mix is Yaapu's excellent lua scripts that give me real time cell voltages and I have been following the 3.5 volt minimums religiously. I have been getting 2-3 minute flight times before I drop below 3.5 volts. There are no cameras or gimbals and not other devices besides a Pixhawk, FRsky radio and a 915 mhz telemetry radio. I decided the old battery were shot even though internal resistance was no higher than 4 or 5 on the SkyRC charger. I purchase a new 5200 3S 50C battery and this morning I had almost identical results. A level 1 warning (1.75v) immediately after take off and a level 2 warning (1.5v) a minute or so later.

The SkyRC replaced 1030 MAh or almost exactly 20% of the fully charged battery.

I am waiting for some 1245 and 1345 props to arrive but I can't imagine they would make a huge difference. I would order new motors but want to understand what is happening with the short flight times before I blow a bunch of money on new motors.

Any insights, comments or suggestions would be most welcome.

This is the auto analyze of this mornings log:

Log File C:\Users\bob\Documents\Mission Planner\logs\QUADROTOR\1\2019-04-24 07-56-52.log
Size (kb) 5099.322265625
No of lines 61007
Duration 0:02:59
Vehicletype ArduCopter
Firmware Version V3.6.7
Firmware Hash 38b8af17
Hardware Type
Free Mem 0
Skipped Lines 0
Test: Autotune = UNKNOWN - No ATUN log data
Test: Brownout = GOOD -
Test: Compass = GOOD - mag_field interference within limits (3.02%)

Test: Dupe Log Data = GOOD -
Test: Empty = GOOD -
Test: Event/Failsafe = FAIL - ERR found: FLT_MODE
Test: GPS = GOOD -
Test: IMU Mismatch = GOOD - (Mismatch: 0.18, WARN: 0.75, FAIL: 1.50)
Test: Motor Balance = WARN - Motor channel averages = [1670, 1624, 1582, 1569]
Average motor output = 1611
Difference between min and max motor averages = 101
Test: NaNs = FAIL - Found NaN in CTUN.DSAlt

Test: OpticalFlow = FAIL - FAIL: no optical flow data

Test: Parameters = FAIL - 'THR_MIN' not found
Test: PM = GOOD -
Test: Pitch/Roll = GOOD -
Test: Thrust = GOOD -
Test: VCC = UNKNOWN - No CURR log data
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Apr 24, 2019, 07:34 PM
Registered User
dkemxr's Avatar
The Auto Analyze function in MP is way behind the current firmware and is of little value. Flight logs will likely uncover something.

Quote:
Originally Posted by Bob AZ
I recently got back to flying copters after a work related hiatus of 4 years. I have an ammo can full of batteries stored at storage charge and an F450 quad and F550 hex plus an unfinished tarot 680 hex. I also have a box of new motors, Sunnysky 2212 980KV and T-Motor 2212 920kv, and and another box full of 1045 Gemfan props.

I recently completed the 680 using the T-motors and 1045s and also a new Tarot 650 quad using the Sunnyskys and the 1045 props. I know these are not the ideal motors and props but I though I'd at least get a couple of usable copters. AUW is 1250gm (With battery)

New to the mix is Yaapu's excellent lua scripts that give me real time cell voltages and I have been following the 3.5 volt minimums religiously. I have been getting 2-3 minute flight times before I drop below 3.5 volts. There are no cameras or gimbals and not other devices besides a Pixhawk, FRsky radio and a 915 mhz telemetry radio. I decided the old battery were shot even though internal resistance was no higher than 4 or 5 on the SkyRC charger. I purchase a new 5200 3S 50C battery and this morning I had almost identical results. A level 1 warning (1.75v) immediately after take off and a level 2 warning (1.5v) a minute or so later.

The SkyRC replaced 1030 MAh or almost exactly 20% of the fully charged battery.

I am waiting for some 1245 and 1345 props to arrive but I can't imagine they would make a huge difference. I would order new motors but want to understand what is happening with the short flight times before I blow a bunch of money on new motors.

Any insights, comments or suggestions would be most welcome.

This is the auto analyze of this mornings log:

Log File C:\Users\bob\Documents\Mission Planner\logs\QUADROTOR\1\2019-04-24 07-56-52.log
Size (kb) 5099.322265625
No of lines 61007
Duration 0:02:59
Vehicletype ArduCopter
Firmware Version V3.6.7
Firmware Hash 38b8af17
Hardware Type
Free Mem 0
Skipped Lines 0
Test: Autotune = UNKNOWN - No ATUN log data
Test: Brownout = GOOD -
Test: Compass = GOOD - mag_field interference within limits (3.02%)

Test: Dupe Log Data = GOOD -
Test: Empty = GOOD -
Test: Event/Failsafe = FAIL - ERR found: FLT_MODE
Test: GPS = GOOD -
Test: IMU Mismatch = GOOD - (Mismatch: 0.18, WARN: 0.75, FAIL: 1.50)
Test: Motor Balance = WARN - Motor channel averages = [1670, 1624, 1582, 1569]
Average motor output = 1611
Difference between min and max motor averages = 101
Test: NaNs = FAIL - Found NaN in CTUN.DSAlt

Test: OpticalFlow = FAIL - FAIL: no optical flow data

Test: Parameters = FAIL - 'THR_MIN' not found
Test: PM = GOOD -
Test: Pitch/Roll = GOOD -
Test: Thrust = GOOD -
Test: VCC = UNKNOWN - No CURR log data
Apr 24, 2019, 07:49 PM
Registered User
Bob AZ's Avatar
Thread OP
.
I thought the auto analyze might reveal something I overlooked. The graph is from the log. The concern is the major drop in voltage triggering a low battery alarm almost immediately.

My 1245 Carbon t-style props arrived tonight. I'll test tomorrow and see if that helps any. I'll switch to T-motors.

Bob
Apr 24, 2019, 08:31 PM
Registered User
dkemxr's Avatar
Some of those errors shown in Auto Analyze are because those parameter names don't exist in Arducopter latest stable. Will your hardware handle 4S? I don't have much flying on 3S any longer. 4S even on the little 130 and 250 size quads, 6S on the larger ones.

Quote:
Originally Posted by Bob AZ
.
I thought the auto analyze might reveal something I overlooked. The graph is from the log. The concern is the major drop in voltage triggering a low battery alarm almost immediately.

My 1245 Carbon t-style props arrived tonight. I'll test tomorrow and see if that helps any. I'll switch to T-motors.

Bob
Apr 24, 2019, 09:04 PM
Registered User
Bob AZ's Avatar
Thread OP
I do have a few 4S and have not noticed a significant difference in flight times. of course the props spin faster and the copter is a bit over responsive. I figured with the 980 and 920 KV motors, a 3S would make more sense. If I'm not able to use my existing motor stock then I'll buy new ones..

I have attached the voltage graph from a 5200 mAh 4S
Bob
Last edited by Bob AZ; Apr 24, 2019 at 09:35 PM.
Apr 25, 2019, 12:44 PM
Registered User
Bob AZ's Avatar
Thread OP
I swapped motors to 920KV T-motor 2212s and mounted 1345 carbon props and with a brand new 5200 mAh fully charged battery getting 4 minutes maximum flight time until my cell voltage drops below 3.5v.

This mornings test flight was hovering at 15 amps , and 3.75v warning went off almost immediately after take off. The battery was at 11.8v when put on the charger and took 1130 mAh of charge, almost 20% of capacity.

I am at a total loss here. Am I being too conservative with voltages. 4 years ago I didn't have the level of telemetry I have today, but I seem to remember significantly longer flight times. Do I need slower motors? The T-Motor 2212s seem to be moderately efficient.

I have attached the voltage graph and the log.

Any suggestions will be sincerely appreciated.

Bob
Apr 25, 2019, 03:22 PM
Registered User
Is any part of your quad hot upon touchdown? Sounds like something is bleeding a LOT of energy. That setup should be getting 15 minutes min. Have your tried ecalc to see the theoretical flight time?
Apr 25, 2019, 06:59 PM
Registered User
Bob AZ's Avatar
Thread OP
Quote:
Originally Posted by too_oblivious
Is any part of your quad hot upon touchdown? Sounds like something is bleeding a LOT of energy. That setup should be getting 15 minutes min. Have your tried ecalc to see the theoretical flight time?
Nope, with the 1045s ESCs and motors are cool to the touch, with the 1355s the motors and ESCs are warm but not close to being hot. I'll give ecalc a shot but I don't have anything else but the Pixhawk, FRsky rx, Telemetry radio.

I am getting 3 minutes from 20% of a brand new 5200 3S battery. Makes no sense.!

Thanks!
Bob
Apr 25, 2019, 07:26 PM
Registered User
dkemxr's Avatar
What's the all up weight of this craft with that battery? I fly everything based on battery capacity and mostly ignore voltage and plan on being on the ground at 80-85% of pack capacity. The only time that has ever been a problem is with the 10c "Multisag" batteries from HK. But even then I have never had a crash from low battery. In fact my longest flight on a 550 quad (42 minutes) was with one of those batteries.

Quote:
Originally Posted by Bob AZ
Nope, with the 1045s ESCs and motors are cool to the touch, with the 1355s the motors and ESCs are warm but not close to being hot. I'll give ecalc a shot but I don't have anything else but the Pixhawk, FRsky rx, Telemetry radio.

I am getting 3 minutes from 20% of a brand new 5200 3S battery. Makes no sense.!

Thanks!
Bob
Apr 25, 2019, 08:00 PM
Registered User
Bob AZ's Avatar
Thread OP
Quote:
Originally Posted by dkemxr
What's the all up weight of this craft with that battery? I fly everything based on battery capacity and mostly ignore voltage and plan on being on the ground at 80-85% of pack capacity. The only time that has ever been a problem is with the 10c "Multisag" batteries from HK. But even then I have never had a crash from low battery. In fact my longest flight on a 550 quad (42 minutes) was with one of those batteries.
I just signed up and ran e-calc.

My AUW is 1462gm With a maximum battery discharge of 20% it projects a hover time of 3.4 minutes, which is about right. I noticed the default was 80% discharge. This is something I never used to worry too much about, as I used to fly on a timer. Am I under-utilizing the battery?? Should I be running an 80% discharge instead of 20%? Then I am at 15 minutes which is what I would expect.

I have been focused on cell voltage alarms ???

Thanks!
Apr 25, 2019, 08:15 PM
Registered User
dkemxr's Avatar
Yes, 80-85% discharge. I just monitor mah consumed on the Taranis. With that battery I would be close to landing at ~4100mah consumed.

Quote:
Originally Posted by Bob AZ
I just signed up and ran e-calc.

My AUW is 1462gm With a maximum battery discharge of 20% it projects a hover time of 3.4 minutes, which is about right. I noticed the default was 80% discharge. This is something I never used to worry too much about, as I used to fly on a timer. Am I under-utilizing the battery?? Should I be running an 80% discharge instead of 20%? Then I am at 15 minutes which is what I would expect.

I have been focused on cell voltage alarms ???

Thanks!
Apr 25, 2019, 08:35 PM
Registered User
Bob AZ's Avatar
Thread OP
Quote:
Originally Posted by dkemxr
Yes, 80-85% discharge. I just monitor mah consumed on the Taranis. With that battery I would be close to landing at ~4100mah consumed.
DUH!!! Thwack..Thwack.. Thwack...Thwack!!! (Sound of forehead hitting desk)
Apr 26, 2019, 07:45 AM
Registered User
Glad it was solved!
Apr 29, 2019, 12:06 AM
Registered User
Bob AZ's Avatar
Thread OP
Quote:
Originally Posted by too_oblivious
Glad it was solved!
Getting there. E-calc has been a real boon in selecting props for both the 650 quad and the 680 hex. I have projected flight times of around 11 and 12 minutes resp. on a 5200 mAh battery without overheating nor being under powered. I'm trying to get away with the 2212s , 920s and 980s, and have ordered a second new 5200 for a parallel hookup. I do have a bunch of 5200 3S which are old and possible a bit beat up. They tend to sag to 10.5 volts on take off while the new battery drops to around 11 1/4.

I am still hesitant to run the new batteries down to 20%, especially when the Tarannis bitch is yelling at me...but I'll take a couple of the old 5200s and run some tests checking on their capacities and IR over time.

Thanks everyone for the help!


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