IOT project to monitor two trailer batteries

Wireless & IoT
1

I have 12V lighting in two enclosed trailers and I want to set up an IOT project to monitor their voltages. Call the trailers T1 and T2. The setup in T1 should upload data to the cloud using a 4G cellular network and T2 should send its readings to T1 wirelessly. Since the trailers normally sit right next to each other, bluetooth can be used. Is there a cellular board that also has bluetooth so that it can accept data from another, simpler board?

Using Sparkfun boards, what do I need to buy?

I’m in Ontario, Canada.

2

We don’t carry much cellular/LTE stuff these days, but Xbee might a good option for ya. For the cell you could use Digi XBee® 3 Low-Power LTE-M/NB-IoT, GNSS, no SIM - SparkFun Electronics and another module such as Digi XBee® RR Module - PCB Antenna - SparkFun Electronics for the other side of things (note you may need a programmer and/or antenna, depending on the model selected)