Battery and Power Management

Battery and Power Management

This guide covers battery monitoring, power limiting, and related features in INAV. For complete technical details, see the official Battery documentation. This wiki page is a draft - feel free to edit if you see anything incorrect or unclear.

Quick Start Checklist

• Enable VBAT feature for voltage monitoring
• Enable CURRENT_METER feature if you have a current sensor
• Calibrate voltage scale (vbat_scale)
• Calibrate current sensor (current_meter_scale, current_meter_offset)
• Set battery capacity (battery_capacity)
• Configure power limits to protect your battery (optional)
• Add battery OSD elements for monitoring

Battery Voltage Monitoring

Setup

1. Enable voltage monitoring:

   feature VBAT
   

2. Calibrate voltage - Measure your battery voltage with a multimeter, then adjust:

   set vbat_scale = 1100    # Adjust until FC matches multimeter reading
   

3. Configure cell voltages (in 0.01V units):

   set vbat_max_cell_voltage = 420      # 4.20V - fully charged (LiPo)
   set vbat_warning_cell_voltage = 350  # 3.50V - warning alarm
   set vbat_min_cell_voltage = 330      # 3.30V - critical alarm
   

INAV will auto-detect the number of cells when you plug in the battery.

Sag Compensation

Battery voltage drops under load (sag). INAV can calculate the unloaded voltage:

set bat_voltage_source = SAG_COMP    # Use sag-compensated voltage (recommended)
# or
set bat_voltage_source = RAW         # Use raw measured voltage

Sag compensation provides more stable readings for alarms and telemetry.

Current Monitoring

Hardware Current Sensor

1. Enable current monitoring:

   feature CURRENT_METER
   set current_meter_type = ADC
   

2. Calibrate - Use a multimeter in series or check against charger data:

   set current_meter_scale = 400    # Adjust for your sensor
   set current_meter_offset = 0     # Offset at zero current
   

Virtual Current Sensor

If you don't have a hardware sensor, INAV can estimate current from throttle:

set current_meter_type = VIRTUAL
set current_meter_scale = 200       # Calibrate based on actual mAh usage
set current_meter_offset = 100      # Current when disarmed

Calibration method: Fly a battery, note INAV's reported mAh, charge the battery noting actual mAh, then:

new_scale = (reported_mAh / actual_mAh) * old_scale

Battery Capacity Monitoring

Track remaining capacity in mAh or mWh:

set battery_capacity_unit = MAH          # or MWH for energy
set battery_capacity = 2200              # Your battery capacity in mAh
set battery_capacity_warning = 660       # Warning at 30% (660mAh left)
set battery_capacity_critical = 440      # Critical at 20% (440mAh left)

The OSD battery gauge will show remaining capacity. The battery must be full when plugged in (>= 4.1V per cell for LiPo).

Power Limiting (Protect Your Battery!)

Automatically limit throttle to protect your from over-current.

Why Use It?

• Prevents exceeding battery C-rating
• Avoids damaging voltage sag
• Extends battery life
• Prevents ESC overheating
• Meets power-limited racing class rules

How It Works

Power limiting uses "continuous" and "burst" limits:

• Burst: High power allowed for short time (punch-outs, climbs)
• Continuous: Sustained power limit for normal flight

When you exceed continuous, you use "burst reserve". When reserve runs out, throttle reduces smoothly back to continuous limit.

Basic Setup

Example: Protect a 1500mAh 4S 50C battery (75A burst, 50A continuous):

battery_profile 1

set limit_cont_current = 500         # 50A continuous (500 deci-amps)
set limit_burst_current = 750        # 75A burst
set limit_burst_current_time = 100   # 10 seconds burst (100 deci-seconds)
set limit_burst_current_falldown_time = 20   # 2s smooth ramp-down

Calculate your limits:

Continuous limit (dA) = battery_mAh × continuous_C_rating / 100
Burst limit (dA) = battery_mAh × burst_C_rating / 100

Example for 1500mAh 50C/75C battery:

Continuous = 1500 × 50 / 100 = 750 dA = 75A (but use 500 = 50A for safety margin)
Burst = 1500 × 75 / 100 = 1125 dA = 112.5A (use 750 = 75A for safety margin)

Power Limiting (Alternative to Current)

Limit by watts instead of amps (useful for racing classes):

set limit_cont_power = 8000          # 800W continuous (8000 deci-watts)
set limit_burst_power = 10000        # 1000W burst
set limit_burst_power_time = 50      # 5 seconds

You can use both current AND power limits together - the most restrictive applies.

Monitoring Power Limits

Add these OSD elements to see limiting in action:

• Remaining Burst Time: Shows how much burst reserve is left
• Active Current Limit: Shows current limit (blinks when limiting)
• Active Power Limit: Shows power limit (blinks when limiting)

When you see blinking, the system is actively reducing throttle to protect your battery!

Disable Power Limiting

set limit_cont_current = 0     # Disables current limiting
set limit_cont_power = 0       # Disables power limiting

Battery Profiles

INAV supports up to 3 battery profiles. Use different profiles for different batteries:

battery_profile 1
set bat_cells = 3
set battery_capacity = 2200
set limit_cont_current = 500

battery_profile 2
set bat_cells = 4
set battery_capacity = 1500
set limit_cont_current = 600

Switch profiles:

• In Configurator GUI (Battery tab)
• Via OSD menu
• CLI command: battery_profile 1
• Stick commands (see Controls)

Auto-switching: Enable BAT_PROF_AUTOSWITCH feature to auto-select based on cell count:

feature BAT_PROF_AUTOSWITCH

Configurator Setup

Configuration Tab → Battery Section

1. Voltage: Enable voltage monitoring, set scale and cell voltages
2. Current: Select sensor type (None/ADC/Virtual), calibrate
3. Capacity: Set capacity and warning/critical thresholds
4. Power Limits: Configure current/power limits (continuous and burst)
5. Battery Profiles: Create profiles for different batteries

Common Issues

OSD shows "NF" (Not Full):

• Battery isn't considered full on plugin (< 4.1V/cell for LiPo)
• Charge battery fully or reduce vbat_max_cell_voltage - 140mV threshold

Capacity drains too fast:

• Calibrate current sensor using charger method
• Check for interference affecting current readings

Power limiting too aggressive:

• Reduce limit_pi_p and limit_pi_i in advanced settings
• Increase continuous limit if battery can handle it

Power limiting causes oscillation:

• Decrease limit_pi_p for smoother response
• Increase limit_attn_filter_cutoff to reduce noise

Advanced Features

Throttle Compensation (THR_VBAT_COMP)

Maintains constant thrust as battery voltage drops:

feature THR_VBAT_COMP
set thr_comp_weight = 1.0

Remaining Flight Time (Fixed Wing)

Estimates time/distance until RTH needed (requires GPS, current sensor, capacity in mWh):

set battery_capacity_unit = MWH
set idle_power = 50       # Power at zero throttle (5.0W)
set cruise_power = 1200   # Power at cruise throttle (120W)

Quick Reference

Feature	CLI Command	Configurator Tab
Voltage monitoring	feature VBAT	Configuration → Battery
Current sensor	feature CURRENT_METER	Configuration → Battery
Auto battery switching	feature BAT_PROF_AUTOSWITCH	Configuration → Battery
Throttle compensation	feature THR_VBAT_COMP	Configuration → Battery

See Also

• Official Battery Documentation - Complete technical reference
• OSD Configuration - Add battery elements to OSD
• Controls - Stick commands for battery profiles
• Settings Reference - All battery-related settings

Tips

1. Always calibrate voltage and current sensors with real measurements
2. Start conservative with power limits, increase gradually
3. Use mWh for capacity if you want accurate flight time estimates
4. Monitor in flight using OSD elements to verify settings
5. Set limits to protect, not restrict - 80-90% of max spec is good practice
6. Test on bench before flying with new power limit settings