> ## Documentation Index
> Fetch the complete documentation index at: https://docs.altnautica.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Power and Runtime

> How to power the ADOS Ground Agent from wall adapters, USB-C power banks, and field power sources.

# Power and Runtime

The ADOS Ground Agent is designed to stay compact. It does not need an internal battery to work in the field. Power it from USB-C using a wall adapter, a USB-C PD power bank, a vehicle adapter, or another regulated field power source.

This keeps the ground node small and lets you choose the runtime you need for each job.

## Recommended power sources

| Source                           | Use it for                           | Notes                                                                                                 |
| -------------------------------- | ------------------------------------ | ----------------------------------------------------------------------------------------------------- |
| USB-C wall adapter               | Bench work, lab testing, fixed setup | Use a supply that can sustain the board's required output under load.                                 |
| USB-C PD power bank              | Field operation                      | Best portable option. Pick a bank with sustained output, not only a high peak rating.                 |
| Vehicle or field battery adapter | Long sessions                        | Use only regulated USB-C output. Avoid bare battery leads into the board.                             |
| Laptop USB-C power               | Short setup only                     | Some laptops limit current. Use separate power when video, WiFi AP, HDMI, or extra radios are active. |

<Warning>
  Do not judge power banks only by the mAh label. Most banks print mAh at internal cell voltage, not at USB output. Runtime should be estimated in watt-hours.
</Warning>

## Expected draw

Use these bands for planning:

| Ground Agent mode        | Expected draw | Plan for                                                    |
| ------------------------ | ------------: | ----------------------------------------------------------- |
| Direct/headless node     |       \~7.5 W | One radio, no HDMI kiosk, normal local clients              |
| Kiosk or dual-radio node |      \~9-11 W | HDMI, browser kiosk, extra radio, or heavier uplink use     |
| Supply ceiling           |          15 W | Power-supply sizing and brownout margin, not normal runtime |

The ceiling matters because weak supplies can reset USB radios during spikes. It is not the number to use for average runtime unless you want a worst-case estimate.

## Runtime estimates

These estimates assume 75-85% usable energy after USB conversion losses.

| Power bank label | Usable energy | \~7.5 W direct/headless | \~10 W kiosk/dual-radio | 15 W ceiling |
| ---------------- | ------------: | ----------------------: | ----------------------: | -----------: |
| 10,000 mAh       |    \~28-31 Wh |             \~3.7-4.1 h |             \~2.8-3.1 h |  \~1.9-2.1 h |
| 20,000 mAh       |    \~56-63 Wh |             \~7.5-8.4 h |             \~5.6-6.3 h |  \~3.7-4.2 h |
| 30,000 mAh       |    \~83-94 Wh |           \~11.1-12.5 h |             \~8.3-9.4 h |  \~5.5-6.3 h |
| 99 Wh PD bank    |    \~74-84 Wh |            \~9.9-11.2 h |             \~7.4-8.4 h |  \~5.0-5.6 h |

Old banks, thin cables, hot weather, and extra devices powered from the same bank reduce runtime.

## USB tether power

USB tether is a data path first. A laptop may also power the Ground Agent, but that is not the recommended field setup.

For reliable USB tether:

* Power the Ground Agent from a wall adapter or USB-C power bank.
* Use a separate USB-C cable that is explicitly data-capable.
* Treat laptop back-power as a short setup convenience only.
* If video freezes or the USB network drops under load, test again with a known-good power source before changing radio settings.

## Brownout symptoms

Power problems often look like radio or network problems:

| Symptom                                     | Likely cause                        | First fix                                  |
| ------------------------------------------- | ----------------------------------- | ------------------------------------------ |
| USB tether appears and disappears           | Host power limit or bad cable       | Use separate power and a known data cable  |
| Video freezes when more clients join        | Supply sag under WiFi load          | Use a stronger USB-C source                |
| Radio adapter disappears from diagnostics   | Brownout on the USB bus             | Change power source and cable              |
| HDMI kiosk works, then drops video          | Load spike from display and browser | Use a higher-output USB-C source           |
| Works on wall power but not on a power bank | Bank cannot sustain output          | Use a PD bank with sustained output rating |

## Field checklist

* Use a USB-C source that can sustain the required output.
* Carry one known-good data cable and one known-good power cable.
* Keep the power bank out of direct sun when possible.
* Start long sessions with the bank fully charged.
* For USB tether, separate power from data whenever the hardware allows it.

## What is next

* [USB Tether](/ground-agent/usb-tether) for wired laptop setup
* [Supported Hardware](/ground-agent/supported-hardware) for board and accessory requirements
* [Troubleshooting](/ground-agent/troubleshooting) for power-related symptoms