Milesight AM102 vs AM102L vs AM103: which ambience sensor?

Short answer: All three are Milesight LoRaWAN indoor ambience sensors in the same 68 × 65 × 20.5 mm housing, with identical temperature and humidity sensing (typ. ±0.2°C from 0–60°C, ±2% RH) and the same EU868 Class A radio. The AM102L has no display. The AM102 is the same sensor with a 2.13-inch black and white E-Ink screen. The AM103 adds NDIR CO2 measurement from 400 to 5000 ppm and a traffic-light indicator. Two questions decide it: does anyone in the room need to read the value off the wall, and do you need CO2?

Which Milesight ambience sensor do I actually need?

Choose the AM102L if the readings will only ever be looked at in software — a BMS, a dashboard, a compliance log. Nobody standing in the room needs the number, so a screen would go unread. It is the cheapest of the three and rated for over 9 years on its two replaceable ER14505 batteries at SF7 on EU868, which makes it the one to specify when you are fitting a lot of rooms.

Choose the AM102 if a person on site has to see the reading without opening an app — a tenant querying their office temperature, a nurse checking a store room, an auditor walking a site. The E-Ink screen is the entire difference, and it costs battery life: over 7 years at SF7 on EU868 rather than over 9.

Choose the AM103 if the question is ventilation or air quality rather than comfort. It is the only one of the three that measures CO2, using an NDIR sensor over 400–5000 ppm at ±(30 ppm + 3% of reading), and it carries a traffic-light LED so a room shows its own CO2 alarm state with no dashboard involved. Battery life falls to around 4.5 years at SF7 on EU868. An AM103L appears on the same datasheet: same sensor, no screen.

What does the L in AM102L actually mean?

The L is the screen, not the sensing. The AM102L is not a lower-accuracy or cut-down AM102. Temperature range and accuracy, humidity range and accuracy, resolution, LoRaWAN radio, IP30 rating, enclosure size, NFC configuration and 1,280 entries of onboard storage are identical on both. The published specifications do not distinguish the two models on any measurement axis. The only differences in the data are the display and the resulting battery life. The AM103 and AM103L follow the same convention.

One consequence before you order the screened version: the sensor is rated −20°C to 60°C, but the E-Ink screen is rated only 0°C to 40°C. In a cold store, an unheated plant room or a loading bay the sensor is inside its range and the screen is not — an argument for the AM102L in exactly the places people assume they want a display.

Is the CO2 on the AM103 worth it?

CO2 is the only measurement the AM103 adds. The measured parameters of the AM102 and AM102L are temperature and humidity, so no setting or downlink will make them report air quality. The trade is real: onboard storage halves from 1,280 entries to 640, battery life roughly halves, and you could fit around three AM102L for the price of one AM103. A common compromise is AM102L throughout for temperature and humidity, with an AM103 in the meeting rooms and classrooms where occupancy drives ventilation.

All three are LoRaWAN Class A devices with internal antennas. None of them is a Wi-Fi sensor — they report to a LoRaWAN gateway on EU868 in the UK, and you need one on site before any of them will send a reading.

Milesight AM102 Indoor Ambience Monitoring Sensor

AM102-868M

£47.88 ex VAT (£57.46 inc. VAT)

DisplayAM102: 2.13-inch Black & White E-Ink Screen (AM102L: Not Support)

View the AM102-868M

Milesight AM102L Indoor Ambience Monitoring Sensor

AM102L-868M

£38.90 ex VAT (£46.68 inc. VAT)

DisplayAM102L: Not Support (the AM102 in the same datasheet carries a 2.13-inch black & white E-Ink screen)

View the AM102L-868M

Milesight AM103 / AM103L Indoor Ambience Monitoring Sensor

AM103

£127.19 – £142.15Price range: £127.19 through £142.15 ex VAT (£152.63 – £170.58 inc. VAT)

DisplayAM103: 2.13-inch Black & White E-Ink Screen (AM103L: Not Support)

View the AM103