Research – Serenity Lake Communications

Over the last 14 years, a remote unheated off-grid cabin has been monitored using a variety of hardware and software solutions. The problems of limited sun and cold temperatures at the Alaska location have been solved using both custom and commercially available equipment.

A custom solution using a low power linux computer with a cellular module was developed by Serenity Lake Communications. This custom solution had the advantage of very low data consumption and very low power usage. For hourly monitoring of 50 data points, data consumption averaged 1/2 megabyte per month. Average power consumption was 1/4 watt.

For full industrial temperature ratings (-40 C to +85 C), the line of equipment from Morningstar Corporation is an excellent solution. Morningstar Corporation provides guidance for cellular or satellite connected monitoring of their equipment. The actual implementation of monitoring is left to the end user. Serenity Lake Communications has developed solutions for monitoring the Morningstar Corporation equipment as well as weather stations, cameras, heating systems and limited security systems.

Rechargeable Lithium batteries are not suitable for use in unheated locations. Lead-Acid batteries have limited power available at low temperatures; however, with proper management, they can be used down to temperatures below -40 C. In multiple year testing at temperatures down to -40 C, extended periods of low sunlight and low temperatures will require reduction of loads to near zero.

Ongoing research is focused on extremely low power and low data usage applications. The available cellular modules have built-in support for PPP, QMI, HTTP(S), FTP(S), SSL, UDP, CoAP, LwM2M, email, SMS and NoIP communications as well as additional features like GPS and special low power modes. In the near future, modules will be available with seamless transition from cellular to satellite communication. Final goal is development of 10 year lifetime with $10 lifetime communications cost (cellular) and 10 year life on 3 AA batteries.

The solar power monitoring system primarily uses cellular data. Satellite transmission of the same or similar data has been tested and developed for use with Iridium Short Burst Data and Swarm (SpaceX VHF data system). Satellite costs are much higher than cellular.