Battery Level Indicator
It is the LED or audible warning that tells the operator how much energy is left in the handheld unit. The indicator mostly interprets the terminal voltage; because the discharge curve of a lithium cell is flat over a wide range, the state-of-charge reading is approximate and drops rapidly in the final part.
A voltage-based indicator compares the cell's voltage under load against thresholds. Because the voltage of a lithium cell changes very little over most of its capacity, the indicator looks full for a long time and then falls to empty in a short time. On an alkaline cell the curve is steeper and the reading is relatively linear; however, in the cold the voltage drops on both and makes the indicator show worse than the actual state.
- Operating rule: do not use the indicator like a remaining-time clock; when it gives a warning, plan to change the unit rather than to continue the shift.
- Misleading case: the level that looks low on a unit coming in from the cold partly recovers once the unit warms up.
- In maintenance: a unit that shows the same level but runs for a shorter time each occasion is a typical sign of capacity loss.
Since battery capacity and operating time are not stated in the product data for the ST/SF sets, it is more reliable to base field planning on keeping records rather than on the indicator.
The context in which this term is used: Wireless Crane Remote Control Selection Guide