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.
     

3691258132?profile=original

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.

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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.

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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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Replies

  • Never got an answer about the I2C... 

    and also is there a plan for a 400A sensor?

    Guy Tzoler said:

    Hi 

    I noticed a I2C port on the hub is it working? can I use it instead of the analog ?

  • For the power modules are now adapter cables available for the Pixhawk 2, with Molex Clik-Mate 6p 2.0mm.
    http://www.mauch-electronic.com/apps/webstore/

    3702279119?profile=original

  • I've been looking at this sensor combo since having a heck of a time getting the calibration correct on my cheapo eBay power module. I finally pulled the trigger after this thread popped back up to the top of the forum and I've read how pleased everyone has been with the product and seller.

    Can't wait to receive it and I'll report back after it's installed. Looking forward to accurate readings and I'm really hoping it reduces the voltage drop I'm seeing under load (1.5V @ 30A hover). Thanks for all the hard work Christian.

  • Hi Sandy... we should not summarize the max. current of the ESC's. Instead, we should look at the estimated hovering current with full payload (AUW).
    Then we use the following rule:
    Current 10-30A = 50A Sensor
    Current 30-60A = 100A Sensor
    Current 60-120A = 200A Sensor or 2x 100A with Sensor Hub X2 (2x LiPo parallel)
    Current 120-???A = 2x 200A Sensor with Sensor Hub X2 (2x LiPo parallel)
     
    So you should select the correct sensor according your UAV... sorry I do not know the hovering current of the 3DR UAV's. However, it sounds a bit strange to me, that they use only a 60A sensor for both UAV's.
     
    REM: Pixhawk will always have the full measurement range same as the attached current sensor. This means with an HS-200-LV, you have a current range from 0-200A = 0.0 - 3.3V



    Sandy Sound said:

    Am I right in thinking a quad using 20amp ESC's needs the 100amp version and an x8 (using 20amp ESC's would need the 200?). I am currently flying the 2014 3DR DIY Quad stock and thinking to upgrade to the X8+ (DIY styles) and want a more accurate power module. I am a little confused because the Quad came with the power module that can read max 60amps (I think) with Pixhawk, but is also fitted on their x8's even though it is double the ESC's. And would the Pixhawk be able to read more than the 60amp limit using your product?
  • Hi 

    I noticed a I2C port on the hub is it working? can I use it instead of the analog ?

  • Am I right in thinking a quad using 20amp ESC's needs the 100amp version and an x8 (using 20amp ESC's would need the 200?). I am currently flying the 2014 3DR DIY Quad stock and thinking to upgrade to the X8+ (DIY styles) and want a more accurate power module. I am a little confused because the Quad came with the power module that can read max 60amps (I think) with Pixhawk, but is also fitted on their x8's even though it is double the ESC's. And would the Pixhawk be able to read more than the 60amp limit using your product?
  • A half year has passed since I introduced the Sensor board and I sold quite a number... thanks to everybody !

    Anyhow, the cable standard or all sensors (50A, 100A and 200A) was 2x 10cm 12AWG wires and only a few guys requested a change to 10AWG. But a 200A sensor with AWG12 is unreasonable and the minimum should be 10AWG or even 8AWG.

    Therefore, I changed the standard for the 200A sensor to 2x 10cm 10AWG, with an option to upgrade to 2x 15cm 8AWG.

    3702260180?profile=original

    • I just wanted to let everyone here know that the service and quality on Christian Mauch's products is stellar. Today I had a 2 wires come lose from my BEC to Sensor board when installing in a new quad. Not being sure of the pin outs, I email him requesting assistance. Literally; within 2 hours, he sent me a diagram and offered to replace the wire harness. He also let me know he is now manufacturing his own wire harness and spent a ton of money on the equipment to do so. Even sent a picture of the machines. Impressive. I hope everyone can appreciate the work and effort he puts into his products and will support him buy buying and using his gear. Nice to see this kind of dedication to service and quality in this age of "make it cheaper and to hell with quality" as with so many other items I have purchased in the past. Some not so cheap either.

  • The 12.0V version of the 4-14S HYB-BEC for FPV is now available !

    3702253052?profile=original

  • I want to use 2 sensors on the same battery to get up to 400A readings from it ... it is a big LIPO :)...

    the dual board should work the same in such case, right?

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