After I had a few problems with the standard power module from 3DR and the ones from Hobbyking, like falling off resistors (overheated) and burned out BEC from voltage spikes, I finally designed my own PM modules. The sensor boards are compatible to Pixhawk, APM, Pixhawk lite, AUAV-X2, DroTek und CUAV Pixhack.

These modules are based on a true hall current sensor, so heat is no more an issue !!!

The sensors boards are able for continuous current of 100A for HS-100-V2 and 200A for HS-200-V2 (no time limit), the maximum over current is 1200A@25'C and 800A@85'C for 1 second.

Here some details:

Sensor Board:

  • Current sensor is a “true hall sensor” up to 200A (ACS758-200U) or 100A (ACS758-100U)
  • Ultra-low noise power supply (LP2985-4.0) for current sensor and offset shifting circuit.
  • Microchip MCP601 operational amplifier for offset shifting.
  • LiPo voltage measurement with 1% resistor divider in factor 9:1.
  • 2x10cm / AWG12 cable soldered to current sensor as standard size (Up to AWG8 possible).
  • 6 pol cable connection to Pixhawk / APM (both sides DF-13 connector).
  • 1x 10cm and 1x 20cm / 6 pole cable in the box to select a different cable length if necessary.
  • 18mm x 29mm x 11mm / 7g without cables and shrinking tube.
     

BEC:

  • Input 2-6S LiPo / max. 28V
  • Output 5.35V / 3A -> +/- 0.05V –> Ripple 10mV (0.2%) at 1.5A output current.
  • Input wrong polarity protection, as well as Panasonic FM 220uF/35V input capacitor to prevent burn out of BEC from voltage spikes.
  • 4 pole cable to sensor board with DF-13 connector.
  • 47mm x 18mm x 11mm / 8g with cables and shrinking tube.

Installation:

The Sensor board is installed only into the positive main battery wire and the BEC should be installed as close as possible to the battery connector.

Quality control of the finished product:

To post here all the quality control during the production would be a very long story, so all I can say is, that it is carried out and recorded.

The final QC before the boards are shipped, is a setup with an FC (Pixhawk) and connected to MissionPlanner to check the calibration values for current and voltage measurement.
This final test result will be passed to the customer together with the order confirmation and shipment tracking number by e-mail.

REM: Which power module supplier out there actually use the PM to power up a real FC before shipment ?

So I hope everybody understands, that if I say "safety first"... then I mean it.

FAQ:

Why Hall sensor ?

  • The measurement over a normal shunt resistor is not accurate at lower current (<3.0A). For a Hall sensor the measurement starts at 0.5A with an accuracy of +/-0.5A over the whole range up to 200A !
  • A shunt resistor create heat due to the voltage drop, the hall sensor has only an internal resistance of 100uOhm, so there is no power loss.
  • Due to the heat created by a shunt resistor and the power cable, the measurement of the current is not linear and depends on the temperature. This is not happened to a hall sensor, a temperature change (created by the main LiPo cable) will not influence the measurement.
  • The current flows only through the hall sensor and NOT through the PCB. Most other current measurement boards has the main cable soldered to the PCB and then it goes to the shunt resistor -> these boards can’t handle over 60A constant current ?

 
Why only a few supplier use a true hall sensor for current measurement in an MR ?

  • Hall sensors are very expensive, compared to a normal shunt resistor and not everybody out there wants to spend the money to top up for a good measurement system. So the sales quantity and profit will not be within the target.


Why output voltage to Pixhawk /APM is 5.35V and not 5.0V ?

  • Pixhawk has internally a 3-way power selector over an ideal diode chip. The 3-ways are USB, power connector (6pin) and the Output PWM rail on the back of the FC. So it is possible to power up the FC with either one of this power sources, but how do we know which power source right know is powering up our FC if there is USB, a PM module as well as an backup BEC connected to the output (ESC/Servo) rail ?
    The answer is easy: Whichever voltage is higher by 0.25V to any other power source is selected as the internal power supply, as long as this voltage do not exceed 5.70V !
    The result in practice on the field can be different, as there are many components connected to the FC like, GPS, Servos, opto ESC’s… etc., the power consumed by the system is not stable, which means the supplied voltage is not stable as well. The reason for this is the loss in voltage due to small power supply cables and maybe many connectors.
    To prevent the internal ideal diode to switch too often between different power sources, we choose a bit unusual high voltage (5.35V) as a main power supply. Which means only if any other power supply (USB or PWM rail) is in the small range of 5.35V+0.25V=5.60V and the maximum voltage of 5.70V, then the diode would switch over to the other source.


Why the cable from UBEC to the sensor board is 4 pol ?

  • To reduce the resistance in the power line and increase the safety, or should we ask, why does the DF-13 power input of the Pixhawk has +/+/I/U/-/- ?
    There are also two wires, for positive and negative, used to reduce the risk of failure.


Why sensor board and UBEC are separated ?

  • A switching power supply can be a very “noisy” part in the power supply chain and it is very difficult to shield the coils (1.5MHz) from the current measurement board. So it was decided to keep the two away from each other.


 Why is there an additional capacitor installed at the input of the UBEC ?

  • Many people complain that the UBEC seems to be bit big, but fact is that he is only 22mm x 17mm. What makes him BIG are the safety capacitors at the input and output !
    We all had the issues before that any ESC burned out due to the “hammer effect” in the supply lines, but do we consider that the UBEC is sitting on the same voltage source ?
    Does anybody ask himself so far why suddenly his BEC burned out ?
    Why does some people add some capacitors onto the ESC’s to reduce the risk of failure, but in the same time they forget that there is also anywhere an BEC in the supply line which might need some protection too ?
    How good is it if your ESC’s survive a voltage spike, but your BEC didn’t and the MR crashes ?
    If you can answer some of the questions by yourself, then you will also figure out why this UBEC is a bit bigger than others.


 How can I get one of these boards ?

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The information in the Product Guide is updated and includes now Pixhawk 2, to make it easier to select the correct parts for your system.

I offer now 10% discount for anyone who want to be ready for the Pixhawk 2 release.
Just enter the Coupon Code PX2 during checkout to enjoy the offer.
www.mauch-electronic.com

REM: Valid until 1st of November 2016

Hi Christian,

I received your 2-lipo kit for Pixhawk1 from the American supplier Craft and Theory a few days ago. When I assembled the wiring, I accidentally soldered the BEC leads to the Y point of the +, and the - parallel harness. Your diagram clearly shows that the BEC leads are soldered to the wires after the Y point. Will my solder job work, or should I rebuild the harness?

Thank you!

Hello Christian, 

I just bought three 200A Mauch sensors and have connected one up as you showed me.  I actually emailed you about it before buying, thanks for taking time responding.  I am having trouble getting the sensor calibrated.  I was reading previous posts and your bit about a serial number posted with each sensor giving a division reading, is that what it is?  Anyway I am running a Pix2.1 with 200A sensor and there was no BEC in stock so I am using the back up power BEC, I hope this is the same.  I am not certain how to measure the current properly to get the right reading or where to enter it.  My multi-meter reads 120 at full throttle and 2 at rest. Mission planner reads 40% at full charge but I just tested it and it took the battery under optimal voltage to 3.00V per cell.  I am not sure how to get this set up and it is very important with my copter at 7KG.  I have built many copters over the years but I have not been able to fully understand the Amps & Current readings. I will post pictures of my meter and the setting I am using etc. Obviously I have set something wrong or I am measuring it with the wrong setting on my meter.

Thanks For making the quality parts I have been having big problems with the Attopilot sensor.

Michael


Christian Mauch said:

The information in the Product Guide is updated and includes now Pixhawk 2, to make it easier to select the correct parts for your system.

I offer now 10% discount for anyone who want to be ready for the Pixhawk 2 release.
Just enter the Coupon Code PX2 during checkout to enjoy the offer.
www.mauch-electronic.com

REM: Valid until 1st of November 2016

Attachments:

I have entered the info on the included paper but I am not sure how to calculate other values.  Perhaps I am not measuring it correctly.  I included my multi meter connection above.  What else are you meant to measure?  How do I connect to calculate it?  What setting do I have on my multi-meter to read it? Where do I enter it in the mission planner page?  

Hi Michael... the setup is explained on my website: http://www.mauch-electronic.com/manual

Yes I have done it right. I will recheck what is going on now the correct values are in.  I thought I had to manually measure the current while throttle was at full.  Maybe not by how I understand the links instructions.  So it looks a lot easier than I first thought. Great thanks. 

Hello Christian, I managed to work out the minor difficulties setting up the divider measurements and now I am setting up my other drone with 2x 200A sensors with the X2 Hub.  I have it set up fine but as far as the alarm/buzzer goes I am a little unsure how to interpret the diagram.  

I can't understand what alarm can we use for this or is it like the standard piezo buzzer witch comes with a pixhawk/Pixhawk2.1 ?  Even if it is the peizo buzzer we are supposed to connect , the buzzer has a positive and a negative wire, yet on the hub diagram connector has a 5 pin plug.  I know the diagram has some words relating to +5.3v, alarm out/5.3v, relays contact's, GND but I still don't feel comfortablejust connecting to positive with my buzzer positive and GND to my buzzers negative wires and hope for the best, these parts are too expensive to go replacing and still not know the right way to connect it.   I also thought there was a safety feature on the X2hub which would land my multi rotor ir a single lipo in paralell dropped below 80% ?  I do not know where to find the documentation regards to what the LED indicator means  if it is solid blue I  take it it is ok, if it is flashing red I take it it is not happy, and yet I thought there was somthing somewhere I read that explained the LED status for each of the 100A 200A etc etc, sensors.  \

As usual I appreciate you helping with these technical difficulties I am having.

Thank you

Michael

 

Thanks

Hi Christian, 

Can you clarify something for me. 

I already am using your a single MAUCH_HS-200-HV on my pixhawk 2.1 Octo setup. 

I either use two batteries or 4 (2 in 2 groups)

I am wondering whether I should get an extra hs-200-hv for the other battery pack(s). And simply connect that to the second pixhawk power input. I'm not sure how the pixhawk will deal with this information but It looks like it will be a little more accurate having both packs to judge from.

I don't really see the benefit in using the the sensor hub as the pixhawk 2 can do pretty much the same job with ardupilot.  

And I'd rather not have to carry another item.

Your input would be appreciated, thanks!

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