SmartHome in the motorhome

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Updated – November 1, 2023

Why SmartHome in a motorhome? The question is legitimate. On the face of it, one would rather assume that this doesn't really make any sense. But, as is so often the case, a second look is crucial. And only when you know that something can be done with relatively little effort does a task arise here and there.

The programming of the functions presented is here linked.

Floor lighting (outside) on driver and passenger side

If you are not on a camping site, but somewhere in no man's land, i.e. far away from street or square lighting, it is helpful if the motorhome lights up in a friendly way when you get into the area of the previously defined "virtual fence".

The lighting is provided by two waterproof 5m LED strips, which are attached below the surrounding apron. The wiring is done separately on the driver and passenger sides. The two LED strips are each connected to one channel of the Homematic 4-way relay module HM-LC-Sw4-WM.

Geofence – lighting control

Homematic / RaspberryMatic have been offering their own geofencing for some time.

A variable is set, the status of which can be queried using a small program and thus the lighting can be activated. Since the geofence can have a radius of around 100m or more, the lighting duration in the program is set to 4...5 minutes, which is usually enough to reach the motorhome, unlock it and get in.

SmartHome also for the dog house in the rear garage

Depending on the temperature prevailing in the dog house compared to the outside temperature, a fan can be switched on, which always promotes cooler air. If you install a polarity-dependent fan, its direction of rotation can be changed according to the temperatures or it can be switched on and off by controlling a suitable relay circuit.

Switching of additional headlights via SmartHome

The vehicle's own reversing "headlights" often don't deserve their name. However, additional headlights may not be connected together with the reversing lights. So you switch it on via your smart home depending on the darkness and an activating click on your cell phone, tablet or manual button.

Two mounted on the side of the trailer coupling are used HELLA additional headlightsthat about a BOSCH relay with a switching capacity of 30A from one channel of the above-mentioned 4-fold relay module.

Thermostatic heating control

Another heating control, most readers will now ask. If you have an ALDE central heating system and do not heat with gas or diesel, but rather with electricity, which is equipped with two switchable levels, the existing thermostat control reaches its limits.

During the transition period, level 1 is often sufficient during the day, while level 2 is required in the evening or at night. However, people often simply forget to turn the heating up as a prophylactic measure. So it would be nice if you just set the temperature and don't have to worry about anything else.

This can be achieved again with the 4-fold relay module mentioned above and a small program. The module's potential-free relay contacts are connected to the switching contacts of the ALDE switching panel and the thermostat contact.

Depending on the temperature difference set and measured on the Homematic wall thermostat, heating level 2 is switched on and the thermostat contact is closed in order to reach the set temperature. If the target temperature corresponds to the actual temperature, the system switches back to level 1. If the target temperature is exceeded, level 1 is switched off.

In this way, in electric operation, rapid heating and maintenance of the target temperature is ensured at the lowest possible level with an accuracy of 0.5 °C.

Selective switching off/on of consumers

In addition to the electric heater, the largest electrical consumer installed as standard in the motorhome is the refrigerator. Depending on the model, it consumes up to around 300 W at 230 V with a duty cycle of around 66 %, corresponding to around 4.75 kW / 24 h.

Together with a 1.5 kW or 2 kW electric heater, such as the ALDE, 1.8 ... 2.3 kW are achieved. A voltage supply on a campsite that is fused with only 10 A, or supply cables that are too long / cable cross-sections that are too small will quickly cause the fuse to respond.

The necessary cross-section of copper cables for DC applications can be calculated here, as can the voltage drop. The yellow fields are editable:

Using the Homematic DIN rail switching actuator with power measurement of type HM-ES-PMSw1-DR current consumption can be determined.

The refrigerator's connection panel is easily accessible from the outside via the lower ventilation opening. There, of course after disconnecting the 230 V power supply, a Homematic 1-channel switching actuator in a top-hat rail housing of type HM-LC-Sw1-DR looped into the phase and the neutral conductor of the supply line.

Since the refrigerator resumes operation without further switching after the 230 V supply is removed and it is reapplied, not only can the heating level be reduced, but the refrigerator can also be switched off, depending on the total load determined.
Exceptional load increases are generally not the norm and therefore switching off the refrigerator for a short period of time is not critical.

Windscreen ventilation depending on the humidity

Niessmann & Bischoff vehicles usually have a roller shutter that separates the windshield from the inside.

Depending on the weather, when the roller shutter is lowered, condensation forms in the lower area of the windshield.

A Homematic type temperature/humidity sensor HM-WDS40-TH-I-2 reports the air humidity and switches on the vehicle's own fan via a free channel of the Homematic 4-way relay module (the level can be selected as desired, the direction of flow should be set towards the windscreen) if a set value is exceeded. Likewise, if the value falls below the relevant value, the ventilation is switched off again.