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# Home Assistant + Shelly on 12V DC: Smart Automation for RVs and Boats
- URL: https://www.goodkit.io/home-assistant-shelly-on-12v-dc-smart-automation-for-rvs-and-boats/
- Published: 2026-03-28T16:57:19.000Z
- Updated: 2026-09-06T01:59:14.000Z
- Description: Most smart home gear is AC-only. Shelly devices work natively on 12V DC — wire them directly to your RV or boat system and control everything through Home Assistant.
- Author: goodkit crew
- Tags: RV, Marine, Sensors, Electrical, Guides

At a glance

Select the relay before planning the automation.

For a 12V circuit, do not buy the AC-powered Mini based on its DC contact rating. Start with the exact model manual and a non-critical load.

[Shelly 1 Gen4 · manufacturer](https://us.shelly.com/products/shelly-1-gen4?ref=goodkit.io)

Most smart home gear runs on AC power. That's fine for a house, but useless on a boat or RV where everything runs on 12V DC.

Some Shelly models support DC power; others do not. Match the exact supply range and relay contact rating to the circuit before buying. Home Assistant can add convenient local automation, but it is not a replacement for independent controls on essential boat systems.

Here's what works, what doesn't, and how to set it up.

## Which Shelly Devices Work on 12V DC

Start by separating the voltage that powers a device from the voltage and current its contacts may switch:

| Model                     | Power / switching distinction                                                                                           |
| ------------------------- | ----------------------------------------------------------------------------------------------------------------------- |
| Shelly 1 Gen4 (full-size) | Stabilized 12V DC or 24–48V DC supply; DC contact limit 10A at 30V. Verify the load and exact manual.                   |
| Shelly 1 Mini Gen3 / Gen4 | AC-powered. Do not buy these for direct 12V battery power.                                                              |
| Other Shelly generations  | Check the exact model’s supply, contact ratings and terminal diagram. Similar names do not mean interchangeable wiring. |

Do not generalize across the Shelly range. Similar-looking devices and different generations can have different power requirements.

## Selecting a Relay for a 12V Circuit

Consider the full-size Shelly 1 Gen4 only if its supply requirements and DC contact ratings fit your circuit. For its stabilized 12V input, a boat’s nominal 12V bus is not automatically a suitable regulated supply.

- Begin with non-critical cabin or courtesy lighting
- Account for motor starting current, not just running current
- Retain independent operation of essential equipment

Budget for appropriate regulation, circuit protection, enclosure and wiring—not just the relay.

The relay supply and dry contacts are separate parts of the circuit. Do not treat this as a universal in-line two-wire accessory.

### Wiring (12V DC)

Use the [manufacturer’s exact-model DC wiring diagrams](https://us.shelly.com/blogs/documentation/shelly-1-gen4?ref=goodkit.io). The generic L/N diagram previously shown here was incorrect for the Mini devices and has been removed. Do not use a diagram from another model or supply mode.

Follow the exact manual for switch-input wiring and configuration. Local switch operation without Wi-Fi still depends on a powered, functioning relay.

Do not use an AC current rating to size a DC load. For motors, heaters or higher-current loads, have a competent installer select the switching hardware, protection and cable.

## The Shelly Plus RGBW PM: LED Lighting Done Right

For LED strips, use a compatible controller and check its per-channel and total ratings at your supply voltage. We discuss the Shelly RGBW approach here, but do not treat a power figure for one voltage as universal.

**Use cases:**

- Dim cabin lights to 10% at night automatically
- Set warm white during evening, cool white during day
- Under-cabinet accent lighting
- Cockpit/exterior lighting with color options

For LED controllers, confirm the strip voltage, channel current, total current and terminal layout against the exact controller manual.

**Pro tip:** Pair it with a [quality 12V LED strip](https://www.amazon.com/s?k=12v+led+strip+warm+white+marine&tag=goodkit08-20&ref=goodkit.io) and you've got better lighting than most factory RV setups for under $40 total.

## The Shelly UNI: Sensor Bridge

The [Shelly UNI](https://www.amazon.com/dp/B08QY35KNR?tag=goodkit08-20&ref=goodkit.io) is different from the relay devices — it's designed for sensor input and low-power switching. It has:

- 2 dry contact outputs (low current only — for triggering other relays, not driving loads directly)
- 1 ADC input (analog-to-digital converter — reads 0-30V)
- Temperature sensor input (DS18B20 compatible)

**RV/boat use cases:**

- Use sensor inputs only within the exact device’s voltage and interface limits.
- A resistive tank sender needs an appropriate interface; it is not a direct voltage source.
- For our tank setup, see the [GX Tank 140 review](https://www.goodkit.io/victron-gx-tank-140-review-put-your-tanks-online/), which distinguishes pressure senders from resistive inputs.

## Setting Up Home Assistant

### Step 1: Install Home Assistant on a Pi

Install Home Assistant on supported hardware with an appropriate power supply. Follow the [current official installation instructions](https://www.home-assistant.io/installation/?ref=goodkit.io) for your hardware rather than an old command copied from a guide.

Home Assistant OS is the straightforward dedicated-device route. Back up the configuration before making changes.

If you prefer Home Assistant Container, follow its current installation documentation and understand the differences from Home Assistant OS.

Connect the host and Shelly devices to the same trusted local network. Keep them off the public internet.

### Step 2: Connect Shelly Devices to WiFi

Each Shelly device creates its own WiFi hotspot on first power-up:

1. Use the exact device manual for initial access.
2. Join your trusted local Wi-Fi network.
3. Keep the device and Home Assistant reachable on that network.
4. Use the Shelly integration in Home Assistant to discover and configure it.

### Step 3: Auto-Discovery in Home Assistant

Home Assistant's Shelly integration auto-discovers Shelly devices on your network. You should see a notification:

**Settings → Devices & Services → Shelly → Configure**

Accept the discovery and your Shelly appears as a switch entity. That's it — no MQTT, no YAML, no configuration files.

### Step 4: Build Automations

Now the fun part. Some practical automations for RV/boat:

Start with non-critical cabin lighting:

Build a simple on/off automation using your real entity names. Test it locally, then test loss of Wi-Fi and a restart before relying on it.

Monitor essential systems without replacing their independent controls:

Home Assistant alerts are supplementary. Do not put a bilge pump’s only control path through Wi-Fi, Home Assistant or a small smart relay.

**Dim lights at night:**

```yaml
automation:
  - alias: "Dim cabin lights after 10pm"
    trigger:
      - platform: time
        at: "22:00:00"
    action:
      - service: light.turn_on
        entity_id: light.shelly_cabin_leds
        data:
          brightness_pct: 15
          color_temp: 400

```

**Battery voltage monitoring (Shelly UNI):**

```yaml
automation:
  - alias: "Low battery alert"
    trigger:
      - platform: numeric_state
        entity_id: sensor.shelly_uni_adc
        below: 12.2
        for: "00:10:00"
    action:
      - service: notify.mobile_app
        data:
          message: "House battery voltage below 12.2V — start charging"

```

## WiFi Considerations

Shelly devices need WiFi. On a boat or RV, that means:

- **Your own router/access point** — A small [GL.iNet travel router](https://www.amazon.com/dp/B073TSK26W?tag=goodkit08-20&ref=goodkit.io) (\~$25) running your own network. Shelly connects to this, Home Assistant connects to this. No internet required for local control.
- **Range** — Shelly devices have decent WiFi radios, but fiberglass and metal hulls can attenuate signal. Place your router centrally.
- **No internet needed** — Everything runs locally. Shelly works without cloud, Home Assistant works without cloud. You can automate your boat at anchor with zero cell signal.

## What About Zigbee or Z-Wave?

Wi-Fi, Zigbee and Bluetooth are different protocols. For example, stock Xiaomi LYWSD03MMC sensors use Bluetooth, not Zigbee. Match the receiver and Home Assistant integration to the device’s actual firmware.

If you're already running Zigbee for temperature sensors, you can mix both protocols in Home Assistant — Zigbee sensors for monitoring, Shelly relays for control.

## Shopping List

Build a parts list for your actual circuit. These are starting points, not a complete installation bill of materials:

## Hardware starting points

- [Shelly 1 Gen4 — full-size model and specifications](https://us.shelly.com/products/shelly-1-gen4?ref=goodkit.io)
- [Home Assistant Green — official hardware and retailers](https://www.home-assistant.io/green/?ref=goodkit.io)

Also allow for a suitable supply, protection, enclosure and wiring. Confirm compatibility before ordering.

A low relay price is useful only if the complete installation meets the job. Compare complete systems, including manual fallback and environmental protection.

## The Bottom Line

Shelly and Home Assistant can make a useful local automation system. The important qualifier is hardware selection: only some models support DC power, and supply voltage is not the same as switching capability.

Start with a non-critical light and verify power, controls and recovery after a restart. Keep independent manual control of essential equipment, including navigation lights and bilge pumps.

Starting from scratch? Our [Home Assistant on a boat or RV setup guide](https://www.goodkit.io/home-assistant-boat-rv-setup-guide/) covers the full picture — install, the integrations worth adding first, and the AI shortcut for writing automations.