I decided to upgrade my previous GPS logger project by adding SIM800L module so that the device can log real-time data into previously created web service ( ).
I had quite a few problems with the SIM800L module. The first module I received was broken and couldn't identify the SIM card. After receiving a replacement module, I had some power issues. The module uses a lot of power when connecting to a network. I measured a current draw of almost 2A during the initial startup of the SIM800L module and current spikes may have been even more. The module would reboot after a few seconds, but that was mainly caused by the cheap battery. If you have a battery with a decent C rating, it can provide the required 2A. I would still suggest using thick short wires from the battery to the SIM module so that the wire resistance can be ignored. Also, it's a good idea to add a 10uF-20uF capacitor just in case to cut down the worst current spikes.
Otherwise, the project was pretty simple wiring between 18650 cell, Arduino pro mini, step up USB PSU, SIM800L module, and NEO-6M module. Notice that protected 18650 cell should be used as the circuit doesn't protect against low voltage.
The current source code does not handle error situations properly. E.g. if mobile network is not available when starting it will never recover even when the mobile network becomes available. However, adding proper error handling should be pretty easy and I may do that during the next weeks.
Project codes can be found from module, eBay: module, eBay: Pro mini, eBay: Boost up PSU, eBay:
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