OpenBeken battery sensor voltage readings show 0.000000 – BL0937, BL0942, BAT_ADC setup and calibration

User question

How do i get voltage readings from my battery sensor?
getreadings command shows:

Info:CMD:Readings are 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000
Info:CMD:[WebApp Cmd 'GetReadings' Result] OK

Artificial Intelligence Response

Direct answer to the question

• “Readings are 0.000000 …” means the measurement path isn’t configured or the sensor isn’t being sampled. In OpenBeken, GetReadings only returns non‑zero values when a supported power/energy driver is active and producing data. For a battery ADC input you must enable and configure the Battery driver (BAT_ADC, optional BAT_Relay) and its calibration; for BL09xx/HW metering chips you must start the correct driver and calibrate it. (github.com)
• Action: decide which hardware you have (energy‑meter IC vs. simple ADC divider) and follow the matching setup below. After correct setup, you’ll see voltage on the Web UI and/or MQTT instead of all zeros. (github.com)

Key points

• GetReadings reports voltage/current/power only if a measurement driver is running. Zeros imply “no data.” (github.com)
• For battery ADC: assign BAT_ADC (and BAT_Relay if present), then Battery_Setup and (optionally) Battery_cycle. Default ADC reference ≈2400 mV, 12‑bit (4096 counts). (elektroda.com)
• For BL0937/BL0942/…: start the matching driver and calibrate with VoltageSet/CurrentSet/PowerSet. (elektroda.com)

Detailed problem analysis

1) Identify your sensor path

• Energy‑meter IC (BL0937/BL0942/HLW/SPDIF‑style): The chip streams V/I/P to the MCU. GetReadings is intended for this path; if the driver isn’t started or pins aren’t mapped, you’ll get zeros. (github.com)
• Battery ADC divider (typical on battery sensors): The battery is scaled by a resistor divider into a BK7231 ADC pin. This uses the Battery driver, not the energy driver; GetReadings isn’t the primary query path here. (elektroda.com)

2) Why zeros appear

• No driver active or wrong one selected (e.g., running GetReadings without a BL09xx driver). (github.com)
• ADC path not declared (BAT_ADC not assigned), so the Battery driver never runs/samples. (elektroda.com)
• Switched divider present but its control pin (BAT_Relay/Bat_Relay_n) isn’t assigned/used, so the ADC always sees 0 V. The Battery driver can toggle this pin automatically if you assign it. (elektroda.com)
• Calibration not set (divider factor), causing plausibly wrong values; raw still shouldn’t be all zeros if wiring is correct. (elektroda.com)

3) Electrical limits that must be respected

• BK7231 ADC reference is fixed ≈2400 mV; scale the highest battery voltage below this with divider Rtop/Rbottom. Vadc_max = Vbat_max × Rbottom/(Rtop+Rbottom) ≤ 2.4 V (add margin). Typical Tuya dividers are ~2.29:1 but vary—calibrate. (elektroda.com)

4) Where you’ll see the number once working

• Web UI: main page shows Battery/Voltage when the Battery driver runs. MQTT: device publishes “voltage” and “battery” topics periodically (default sampling ~10 s) unless you change Battery_cycle. (elektroda.com)

Current information and trends

• OpenBeken’s Battery driver autostarts when any GPIO is assigned BAT_ADC, optionally gating the divider via BAT_Relay/Bat_Relay_n, sampling every ~10 s by default. Battery_Setup sets vmin/vmax and calibration (divider, vref, ADC bits). (elektroda.com)
• GetReadings is a short command intended for power‑sensor stacks (returns V/I/P as a single ASCII line for easy parsing). (github.com)
• BL09xx energy devices require post‑flash calibration using VoltageSet/PowerSet/CurrentSet if factory values were lost. (elektroda.com)

Supporting explanations and details

• ADC chain math: Vadc = (raw/(2^N−1)) × Vref; Vbat = Vadc × vdivider. Default Vref ≈2400 mV, N=12 (4096). Divider “vdivider” is the ratio to reconstruct battery voltage. (elektroda.com)
• Switched dividers: many Tuya boards save battery by switching the top resistor with a FET. The driver asserts BAT_Relay, waits a short time, samples, then releases it. (elektroda.com)

Ethical and legal aspects

• Do not rely on simple voltage mapping for Li‑ion cell safety. Enforce proper cut‑off and use certified protection/charger ICs to meet safety standards (e.g., IEC 62133, UN 38.3). The firmware’s Battery_Setup only maps ADC to a %; it does not provide protection. (elektroda.com)

Practical guidelines

A) If your device uses an energy‑meter IC (GetReadings target path)

• Load the correct template or set pins, then start the driver for your chip (examples: BL0937/BL0942). Use the supported devices list or your device’s template for exact pins. (github.com)
• Calibrate: VoltageSet , CurrentSet , PowerSet . After this, GetReadings should return non‑zero V/I/P. (elektroda.com)

B) If your device is a battery ADC divider (most battery sensors)

1. Assign GPIO roles:
   • setPinRole BAT_ADC
   • If your PCB has a switched divider: setPinRole BAT_Relay or Bat_Relay_n (depends on polarity)
   • Optionally place them on a channel with setPinChannel, though the Battery driver will still work when BAT_ADC is assigned. (elektroda.com)
2. Start or confirm driver is running (usually autostarts with BAT_ADC):
   • startDriver Battery (harmless even if already running). (elektroda.com)
3. Calibrate and set chemistry window:
   • Battery_Setup [vdivider] [vref_mV] [adcbits]
   • 1S Li‑ion: Battery_Setup 3000 4200 4.03 2400 4096 (example for ~1M/330k divider)
   • 2×AAA alkaline: Battery_Setup 2000 3000 2.29 2400 4096
   • Adjust vdivider until the reported voltage matches your multimeter. (elektroda.com)
4. Control sampling:
   • Battery_cycle (default ≈10). Set 0 for “no periodic sampling” (one‑shot via scripts/wake). (elektroda.com)
5. Verify:
   • Watch the Web UI battery/voltage fields or subscribe to voltage/battery MQTT topics. You should now see non‑zero values. (elektroda.com)

Quick hardware sanity checks (common to both paths)

• Ensure battery negative and module GND are common.
• With a multimeter, check the ADC pin node while the divider is enabled; you should see a few hundred mV up to <2.4 V proportional to battery voltage (never exceed Vref). (elektroda.com)

Possible disclaimers or additional notes

• Divider tolerance directly shifts reported voltage; expect 1–5% error unless calibrated. (elektroda.com)
• Some firmware builds change Battery_Setup argument order; use the on‑device help/release notes for your exact version if a syntax error appears. (elektroda.com)

Suggestions for further research

• OpenBeken “GetReadings” and console usage overview (where it’s defined to return V/I/P). (github.com)
• Battery driver background, defaults, and command set (BAT_ADC, Battery_Setup, Battery_cycle). (elektroda.com)
• Energy‑meter calibration guide (VoltageSet/CurrentSet/PowerSet) for BL0937/BL0942 devices. (elektroda.com)
• If you don’t know your device pins, use the OpenBeken supported devices/template list for a ready‑made mapping. (github.com)

Brief summary

• GetReadings shows zeros because no measurement driver is producing data. If you have an energy‑meter IC, start/configure its driver and calibrate; if you have a battery ADC divider, assign BAT_ADC (+ optional BAT_Relay), run Battery_Setup, and then read voltage from the UI/MQTT. After these steps you will get non‑zero voltage readings. (github.com)

If you share your exact device model, sensor type (BL09xx vs. ADC divider), and which GPIOs are wired, I can give you a copy‑paste command set tailored to your board.