The most reliable way to create a "low battery alert" on the battery powered devices is to use the "Battery Good" flag.
Alert with Battery Good Flag
The Battery Good flag is sent by the device in the status bits of the device data. It takes into account the battery chemistry and device characteristics.
It is usually more reliable than simply setting an alert at a predefined voltage.
This article provides some more details on exactly how this flag works.
To do this in Telematics Guru, follow the "Low Battery" alert setup in the Alert Wizard. (see - Set up an Alert with the Wizard)
Or, under advanced, setup the conditions tab like this:
If not using TG, alert off the battery good status flag.
The Battery Good flag mentioned above is the preferred setup. However, it is also possible to create analogue based alerts. The alert could be based on a predefined battery voltage or battery percentage. This will work in most cases, but it does not take advantage of the smart firmware features, such as:
- Remora on LTC's use the Loaded Voltage, not the normal battery voltage. The Battery Good flag above takes this into account.
The alerts can be setup according to your requirements. See this article for a discussion of the various battery capacity indications and how they can be used.