# VOXL PM v3 (MDK-M0041-1-B-03): VBAT INA231 @ 0x44 missing (only 0x45 seen) → no `battery_status`

Source: https://forum.modalai.com/topic/4667/voxl-pm-v3-mdk-m0041-1-b-03-vbat-ina231-0x44-missing-only-0x45-seen-no-battery_status
Category: General Questions (https://forum.modalai.com/category/2/general-questions)
Posted: 2025-08-11 19:46:48 UTC by hula
Replies: 0 · Views: 359

## hula · 2025-08-11 19:46:48 UTC

![IMG_20250810_121243176.jpg](https://forum.modalai.com/assets/uploads/files/1754941587158-img_20250810_121243176.jpg) 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: increasing

voxlpm 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
1) 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)?
2) Is there any production variant of this PM where U3 is DNI or strapped to a different address than 0x44?
3) 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?
4) 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:
 
![IMG_20250810_121216316_HDR.jpg](https://forum.modalai.com/assets/uploads/files/1754941598069-img_20250810_121216316_hdr.jpg) ![IMG_20250810_121243176.jpg](https://forum.modalai.com/assets/uploads/files/1754941601260-img_20250810_121243176.jpg)