I’m doing a hexacopter build with two 4-in-1 ESCs. One of them is from the flight controller manufacturer and its current sense wire is connected in the standard way. I want to connect the current sense wire of the second one to a spare Rx, then configure it so that the sum of both is displayed as my current draw. (and used to calculate mAh used) My understanding is that this can be done but I wanted to confirm for sure and ask if someone can help me configure this properly.
Spare Rx? I belive current sense wire is analog signal, and You need FC with second analog input for that.
You could use just one analog current sense from one ESC but double (or x1.5 for 6 motors) the Amps per volt value to approximate double the current.
OR
Just use the DSHOT data and set the battery monitor accordingly. In that case voltages are averaged and currents are summed.
All of that depends on what flight controller you have, and exactly which ESCs.
Please provide more details.
This is exactly what I want, averaged voltage and summed current values.
Hardware is FC: MicoAir743V2
ESC1-4 MicoAir Bluejay-4IN1-60A
ESC 5-6 RuiBet 55A Bluejay JHEMCU RuiBet 55A 3-6S Dshot600 BLHELI_ S four in one electric regulator FPV
I don’t think I have another anolog input on my UARTs.
Something which is a little confusing to me is that the MicoAir 743v2 lists UART 7’s RX as being ESC telemetry (is this what’s used for the current sensing?) and says it’s pin PE7 on the FC, but I don’t see PE7 being connected to an ADC (for analog input) in the H743 pinout I found online. (Maybe, the pinout I’m looking at is wrong and I do have other analog Rx pins.)
Normally for ESC You have 8 lines:
2 lines for power
4 lines for each motor
1 line for serial port (not sure what is actually transmitted there)
1 line for current sensing.
And in the mentioned FC specs:
Soo… I guess no more ADCs available, and dshot would be the only option to get actual current readings.
Not sure how much You want to stick to FC You havem but there are FC with second set of voltage/current lines - like MATEK H743-SLIM V3 - it has Vbat2 and Curr2 pins for that purpose (not sure if arducopter makes use of them, needs to be verified. EDIT: Just checked, and it does work)
Mmm, BlueJay ESCs dont have the telem data output 
Even a lot of BLHELI32 or AM32 ESCs dont output the current data, only the analog current like you already have.
I’m starting to think your best bet is to use the analog current output from the ESC used for 4 of the motors, and adjust the multiplier to give an approximation of the current draw of all 6 motors.
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Use one I2C battery monitor on the battery lead.
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I think this is the route I’ll go with. Can you please let me know how to adjust the multiplier?
I’m probably going to stick with the current FC. The build is basically done besides closing the frame and putting on the props. Lot of wiring splices already done just to get everything connected to the FC. (it uses connectors for EVERYTHING)
Change BATT_AMP_PERVLT
Probably multiply the default value by 1.5
This is how you get it quite accurate:
- Plug in a fresh battery and do a hover flight for 5 minutes or until you’ve used a significant amount of battery capacity
- Immediately unplug the battery and charge it, note how many mah’s it took to charge. Let’s say that was 1,500 mah
- Download your log and look at maximum Bat.CurrTot. Let’s say it was 1,300 mah
- Get your existing BATT_AMP_PERVOLT setting from Mission Planner, let’s say 17
- NEW_AMPS_PER_VOLT = OLD_AMPS_PER_VOLT x CHARGED_MAH / LOGGED_MAH
With my example numbers, you’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 you’re happy the new value gives consistent readings
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Thanks, I did that. Will hopefully give it its Maiden Flight in a few days.
edit: MicoAir* gives current output as * Current Sensor Output: 12.75mV/A
so I’m guessing I should set it to 1.5 * 78.43 A/V So about 117.6.
Yes you are on the right track.
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Good idea Dave!
There’s no calibration to be done 
and there’s a few around now
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Yea, those Matek boards seem to be popular. Can’t beat 150A, 8S for ~$20 with an I2C interface!
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Those sensors could fit my build perfectly. (6S Voltage, 6x 3115 900kv motor, 10x5x3 prop, shouldn’t go over 150A when spraying the garden (<2A pump and <7kg AUW with a gallon of water)) And my both my I2C AND CAN ports/busses are totally free/unused right now. At some point in the future, I might throw one of these current sensors into the build. Thanks for letting me know about them!