Low battery
A low-battery rule alerts you when a tag's battery drops below a voltage you set, so you can replace or recharge tags before they go dark and stop reporting.
Low-battery rules work with any tag that reports its battery voltage. See position history and sensor data for how sensor readings arrive.
How it works
You set a threshold voltage in volts. When a tag's latest battery reading falls below it, the rule raises an alert. The alert clears automatically once the battery recovers — but to stop it flapping on and off while the voltage hovers around the threshold, recovery uses a small buffer: an active alert clears only once the voltage rises 0.1 V above the threshold.
Battery voltage is a better early warning than a percentage: most BLE tags run from about 3.6 V when full down to roughly 2.0 V when flat, and the voltage drops off sharply near the end. A threshold of around 2.6–2.9 V gives you time to act before a tag dies.
The alert message names the tag and the reading, for example:
Battery voltage 2.85V is below threshold 2.90V
Parameters
| Parameter | Description |
|---|---|
| Threshold voltage | Alert when the tag's battery falls below this voltage (default 2.9 V). |
| Auto-resolve | On by default: the alert resolves once the battery rises back above the threshold (plus the 0.1 V recovery buffer). Turn it off to keep the alert open until you resolve it manually. |
See the rule types reference for the full parameter specification.
Example: keeping a fleet of labels alive
A warehouse tracks pallets with battery-powered smart labels.
- Create a low-battery rule with a 2.7 V threshold, at medium severity.
- Add a webhook or email notification to the maintenance team.
- As labels age, each one raises an alert while it still has enough charge to be swapped, so pallets never go untracked.