VOXL PM v3 (MDK-M0041-1-B-03): VBAT INA231 @ 0x44 missing (only 0x45 seen) → no `battery_status`
-
Hardware- Flight controller: ModalAI Flight Core v2
- Power module: VOXL Power Module v3, P/N MDK-M0041-1-B-03 (silk: “MODALAI APM LITE / M0041 REV?”)
- Power applied via XT60 (battery), FC connected to PM on J13 (I²C back to FC).
Firmware
PX4 (ModalAI build). (I can provide the exact git tag if needed.)
Symptom
listener battery_status
-> never published
What I see
I²C scan on the PM bus (I²C3 / bus 3): 0x45 present, 0x44 absent.
voxlpm start -X -a 0x45 -T P5VDC
-> voxlpm #0 on I2C bus 3 (external) address 0x45
voxlpm status
-> - V3 (INA231) type: P5VDC
voltage: 5.0475 VDC
current: 0.4464 A
shunt: 2.5000 mV, 500.0000 mA
rsense: 0.005600 ohm, cal: 4993
sample: increasingvoxlpm start -b 3 -a 0x44 -T BATT
-> WARN [SPI_I2C] voxlpm: no instance started (no device on bus?)
Visual inspection
The INA231 near “BAT OUT” is marked U3 (expected VBAT monitor @ 0x44).
Nearby strap resistors/jumpers: R12 is not populated, R13 is present. Docs indicate U3 should be strapped A1=VS, A0=GND → 0x44.
Hypothesis
Either U3 (INA231) is unpopulated/failed or its address strap isn’t set for 0x44 (e.g., missing 0‑Ω link at R12 if that is A1→VS).
Since 0x45 (U4 / 5 V rail) works, the I²C path, driver (voxlpm), and power to the PM are good.
Questions for ModalAI- On MDK-M0041-1-B-03, can you confirm the intended A1/A0 strap for U3 and which designators implement those straps (e.g., R12 = A1→VS, R13 = A0→GND)?
- Is there any production variant of this PM where U3 is DNI or strapped to a different address than 0x44?
- Given the measurements above, do you recommend an RMA for this module, or is it acceptable to populate the missing strap (R12) to A1→VS to restore 0x44?
- Any additional checks you’d like me to run (specific test points for U3 VS, A0, A1)?
Attachments
Close-ups around U3, R12/R13, and the SDA/SCL/GND/5V header:

Reading along? Create a free ModalAI Forum account to join in.
With an account you can reply, ask your own question, get an email when a ModalAI engineer answers, and mark the reply that solved it. Your place in each thread is saved between visits.
Questions about VOXL, Flight Core, ESCs and ModalAI drones are answered here by the engineers who build them.
Register Login