Setup and Requirements
Measuring the average power consumption of a radio device, such as a Meshtastic node, requires some equipment and knowledge.
Power Meter
You need a way to measure power. This could be a bench power supply that shows voltage and current readings, a dedicated USB power meter, or another similar tool. The key point is that you must be able to read either volts and amps or watts over time. (Measuring over time means tracking power consumption continuously, not just taking instant readings.) Also, make sure your meter is sensitive enough to measure the low currents your device may draw—for example, some nodes consume as low as 0.005A at 5V. The most important feature is that the meter can record amp-hours or watt-hours, as a typical multimeter does not have this capability.
What Are We Measuring?
Power is measured in watts. To find out how much power your device consumes, you multiply volts by amps to get watts. For example, 5V multiplied by 50mA equals 250mW (or 5V x 0.05A = 0.25W). This number represents power consumption at a particular instant and technically means the power consumed over one hour. However, this snapshot isn’t enough because radio devices like Meshtastic nodes spend most time receiving and less time transmitting, with transmissions drawing considerably more power. Measuring only the receive power and assuming that constant consumption would ignore the higher power used in transmissions. Hence, what’s needed is the average power consumption over time, which is expressed in watt-hours. For instance, if a device consumes 250mW for one hour, over a 24-hour period it consumes 24 x 250mW = 6000mWh, or 6Wh.
Duty Cycle
Radios use less power when receiving, and significantly more when transmitting. Duty cycle defines the percentage of time the radio is transmitting during a given period. This could be 5%, 10%, 25%, or another value, depending on your application. Instead of calculating average power based on datasheet values for receive and transmit modes, it’s better to perform a real test measuring power consumption over time. Run the test for at least one hour; longer tests (2-6 hours) provide more accurate results if they reflect real operating conditions.
Test Conditions
Testing is simple but requires understanding how Meshtastic works behind the scenes.
Background Network Activity
Meshtastic nodes regularly send data packets in the background. These are not user messages but network beacons that indicate a node's presence and location (for GPS-enabled nodes). Other nodes acknowledge these beacons. This baseline network traffic consumes power through both receiving and transmitting, regardless of manual message sending. Some of these transmissions can be disabled or reduced, but they must be considered as ongoing power use.
Simulated Testing
To simulate actual message traffic, adjust how often the device broadcasts GPS location updates—this mimics manual messages on the network. The default broadcast interval is 2 minutes for GPS nodes and 15 minutes for nodes with fixed positions. Shortening this interval increases transmission frequency, which increases power use. This setting can be adjusted via mobile apps or CLI. Use this feature to simulate message traffic automatically during the test.
Fixed Position Broadcast Interval
Solar base stations often lack GPS modules because their location is fixed, and GPS consumes considerable power. In Meshtastic, you can manually set a node’s fixed coordinates. Nodes with fixed locations broadcast their position every 15 minutes by default (four updates per hour). To simulate more messages—for example, 16 per hour—reduce the broadcast interval to 3 minutes; for 56 messages per hour, set it to 1 minute.
Example Test Condition With Node Settings
Testing requires at least two nodes: the test node and another node. For realism, use three or four nodes. A "chatty" network setup might be:
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Three nodes in the network.
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One node broadcasting location every 60 seconds (disable smart location).
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Test node paired to a phone via Bluetooth.
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Test node set with a fixed GPS position.
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Test node broadcasting location every 60 seconds (disable smart location).
Start the test at a round time (for example, on the hour or quarter-hour) and note the start time. Reset any prior measurements on your power meter before beginning. After the test duration, note the stop time and the total power consumed.
Results
Your meter should report total power used in watt-hours. Divide this value by the test duration in hours to get the average power consumption in watt-hours or milliwatt-hours. Keep this result for the next step—calculating solar panel size.
If your meter reports amp-hours, convert to watt-hours by multiplying by the test voltage. For example, if over a 3-hour test at 5.1V the meter shows 142mAh, then total energy used is 5.1V x 142mAh = 724.2mWh. Divide by 3 hours to get 241.4mW average consumption. Save this figure for further calculations.
Detailed Power Consumption and Battery Life Comparison
Here is a focused comparison between the nRF52840 and ESP32 in terms of power consumption and expected battery life using a 1000mAh battery (assuming a 3.7V Li-ion cell):
| Parameter | nRF52840 | ESP32 |
| CPU Clock Speed | 64 MHz | Up to 240 MHz |
| Active Mode Current | ~5.3 mA (CPU active) | 80-260 mA (Wi-Fi transmission peak) |
| Deep Sleep Mode Current | As low as 0.4 µA | 10-150 µA (deep sleep mode) |
| Bluetooth Low Energy (BLE) Tx | ~4.6 mA | ~30 mA |
| Wi-Fi Active Current | None (no Wi-Fi module) | 80-260 mA |
Using these typical current draws, we can estimate battery life as follows:
| Scenario | Estimated Current (mA) | Estimated Runtime with 1000mAh Battery (hours) |
| nRF52840 Normal Operation | 5 mA | 200 hours (approx. 8.3 days) |
| nRF52840 Deep Sleep | 0.0004 mA (0.4 µA) | 2,500,000 hours (theoretical limit) |
| ESP32 Wi-Fi Active | 150 mA | 6.7 hours |
| ESP32 Deep Sleep | 0.1 mA (100 µA) | 10,000 hours (approx. 416 days) |
