The system itself

Two instincts point inwards, at Sensa rather than at the van. They are the ones that keep the others honest.

Sensor gone quiet

The instinct that guards the others. A wireless sensor running on a coin cell does not announce that its battery has died, it simply stops reporting, and every instinct relying on it quietly stops watching too. This one notices, and names the sensor that went quiet.

It covers every environment temperature sensor in the van. It deliberately does not fire at start-up, because everything wireless is briefly unreachable while the system boots, and it checks once an hour as a backstop so a sensor that died while the van was powered down is still caught.

Settings: Quiet for 30 min, range 10 to 240, in steps of 5.

Default: Alert.

You need: at least one wireless environment sensor.

Storage space

Sensa keeping its own house in order. It watches its storage and says something long before running out could become your problem.

This is the one instinct with two fixed levels instead of a Warn or Alert choice. It warns at the first threshold and raises a full alarm at the second. If you set the two the wrong way round, Sensa quietly puts them back in order so the alarm can never sit below the warning.

Settings: Warn above 80%, range 50 to 95. Alert above 90%, range 60 to 99.

Default: both levels, as described above. There is no Warn or Alert chooser on this one.

You need: nothing. This instinct is available on every system.