10" Quadrotor Battery Life Very low - Brand New Battery

Hardware Multirotors
1

Hi there,

I am working on a 10" Quadrotor that has the following specs:
10x4.7 APC props
4x 18A ESC
4x 920Kv Motor ( max 16A)
11.1v 5000mAh GoldBat (Brand New)
Hover Current is 11-12A.

When I do some basic math I get about 20 min run-time. If I put these values as close as possible in eCalc I also get about 18-20 min (at 80%).

In real world I am currently getting 5-6 min. At this point the FC shows the battery consumption is just under 1000mAh.

Is this battery just low quality and not able to preform? Or will I get the same performance with Lumiere or Tattu.

Thanks,

2

Assuming your current sensor is calibrated properly, I would definitely say that the battery is the problem. I had no experience with GoldBat. I think a fresh Tattu or GNB would perform as expected.

Another possibility is that you have a calibration issue and a suboptimal tuning which consumes way too much current which is then displayed incorrectly. But if you can confirm that say 5A in logs correspond to 5A measured by an external tool, and 10A is 10A, then everything else is OK and you just need to replace the battery.

3

Hi there Max,

Thanks for the feedback, there is local vendor with GNB

First I will test the current sensor, It is Cube Orange + and I am using all the provided values but I will test.

4

So the issue is the current sensor.

At Idle the Cube reads 0.0A, but I can see it is drawing 2.1A, and the Voltage drop shows this.

I set it to CUBE HV Power Module and Cube Orange. ( this has AMP/Volt at 39.9, I can try and adjust this but Iā€™m not sure of the correct value)

The manual shows a complete different set of values. But they gave incorrect readings too. Its all very unclear.

5

Itā€™s simple to determine. Go here:
Calibrating current sensor

1 Like
6

So I did this but its still completely out of wack.

Original value is 39.9
Calculated value was 69
I have even tried 200, this was close but the current is all over the place (4, then 6 then 8 then 4. other meters show 8A consistent.)

What could be the issue, it seems it is related to some kind of calculation, on startup the Cube is drawing 600ma, Shows 0.01A, way off. Then when armed the values goes to 0 and shows nothing. ( but meters show 2.1A) is it defective? why would the current show less when the motors start.

Thanks.

7

Sometimes a cheap charger can cause your original issue, short flight time, because the battery is never fully charged.

Ignore very low current readings below say 5amps - that sort of sensor and many like it can not measure accurately down low. Thatā€™s why the real current calibration is performed with hover flights.
Also check and accurately set your voltage multiplier, calibrate it at a low voltage not with a fully charged battery.
Use these battery related settings if you havent already - do not adjust them to try and gain more flight time or the battery just gets damaged.

BATT_ARM_VOLT,11.00
BATT_CRT_VOLT,10.50
BATT_LOW_VOLT,10.80
MOT_BAT_VOLT_MAX,12.60
MOT_BAT_VOLT_MIN,9.90
1 Like
8

Hi there Shawn,

Yes the failsafe is set and I donā€™t plan to change.

I will do some tests with 10A and see the results but I suspect the 11A that was logged is not correct, but if the capacity is correct then possibly the calibration is ok.

So far I have not found many vendors to make batteries in this size, the only options are Gens Ace , Lumenier, or GNB. all~5000mAh.

9

Did you find the current calibration procedure in that other thread? We use that because most people dont have current meters that can do more than 10amps, and it becomes tricky to draw that much current on the bench when youā€™ve already got your copter built.
You do need a charger that reports the number of milliamp hours returned to the battery.
This procedure gives a surprisingly accurate result.

Hereā€™s how to adjust your Amps Per Volt

  • Plug in a fresh battery and do a hover flight for 5 minutes or until youā€™ve used a significant amount of battery capacity
  • Immediately unplug the battery and charge it, note how many mahā€™s it took to charge. Letā€™s say that was 1,500 mah
  • Download your log and look at maximum CurrTot. Letā€™s say it was 1,300 mah
  • Get your existing BATT_AMP_PERVOLT setting from Mission Planner, letā€™s say 17
  • NEW_AMPS_PER_VOLT = OLD_AMPS_PER_VOLT x CHARGED_MAH / LOGGED_MAH
    With my example numbers, youā€™d get
    NEW_AMPS_PER_VOLT = 17 x 1,500 / 1,300 = 19.61
  • Set the new value in the BATT_AMP_PERVOLT parameter and save to your copter
  • Fly to check, repeat until youā€™re happy the new value gives consistent readings
1 Like
10

So I did some flights and closely monitored the mAh.

To get the changer and FC to be close the amp_per_volt was set to 70. this means the copter is using 20A at hover! This seems like alot and much higher than ecalc shows for (similar) motors.

I suspect the low Flight time is due to the low C rating of this battery (25C) and I will try and get some 50 or 100C ones to test.

11

Post a link to a flight log after you set the amp/v to 70.

12

@Tristan_Redish , I donā€™t think that your flight tim is due to low C rating as you said.
For your battery 25C means that you can throw up to 25 * 5000mA = 25 * 5 A = 125A but your power consumtion ist only 20A at hover meaning only 4C.
If your power consumption is higher as expected the reason is somewhere else but not the battery from my understanding.

13

@dkemxr Log attached here.

@Juergen-Fahlbusch I agree that the actual load is only 4C, but the performance of 25c vs 50c battery will be quite different.

When the Copter is in flight the battery alarm triggers after going below 10.5V. (about 6 min) When this happens after disarm the battery voltage returns to ~11.3 and when charged the battery is showing ~1600mAh charge. ( this is a 5000mAh battery), showing that the battery is not fully depleted but it cannot sustain 4C at 11.3 static voltage. ( My hope is that a 50C battery can maintain 4C load for a longer time).

Please correct me if Iā€™m incorrect about this.

First log is with Default Cube Power Sensor settings.

2nd log is with Amp_Per_Volt set to 70.

14

@Tristan_Redish if it is true, that you recharge 1600mAh after 6 min flighttime you throw about 14.5-15.0 A. If this is the case you are right a Battery with more ā€˜Cā€™ might be better but still this is not the initial problem, the main problem is why your drone is taking so much power in that case. And also did you checked the battery voltage parallel with a multimeter directly to the contacts at the battery. Probable you also have to much lost on your cables.

15

Can you supply a couple of photos of your wiring?

16

@xfacta, You can see this main power wiring in this picture.

The battery goes directly to the power sensor then to the PD board. ( wires in grommet on middle shelf)

Battery voltage is matching what the FC is reading so there is no issue there.

Any ideas are greatly appreciated, Thanks.

17

Ah yes - I remember this one. Maybe time to lose those big ā€œfeetā€.

Maybe the battery capacity is not as advertised - you should get at least double that mAh used.
Set BATT_FS_VOLTSRC,1 to use the sag-compensated voltage and see how that goes.

18

How much does your machine weigh?

19

@geofrancis

The quad weights 990g without battery and 1380g with battery.

I have tested the battery on a load tester @18A and the voltage sag still isnā€™t as bad as what is seen during flight. (I do lots of indoor flights so in that case Iā€™m willing to push the battery a bit further.) its clear that with wind and only 6 min of runtime, outdoors will not be ideal for this quad.

I have thought about going to 4s to gain a bit more thrust with a bigger battery but I have to see if all the components are rated for 4s.

Still donā€™t really understand why the quad draws 25A at hover though, seems high. ( and yes still prop gaurds and landing feet.)

20

Those propellers might be a bit big for the motors, they are 10" but they are really wide slo-fly propellers. I would try something a little smaller like 9045.

The foam feet will be catching a lot of prop wash try without them to see how much the power consumption drops.

1.4kg is right on the edge of what i would try and fly on 3s. 4s will be better but you will need to fit smaller 9 inch propellers.