Battery

On a lamp with a battery, its level is shown on the lamp's page, together with an estimate of the time it has left at the current brightness and effect. The estimate changes as you change the brightness or the effect - brighter and busier means shorter.

The level follows how these lamps' batteries actually run down, measured on full charges from full to empty, so it falls evenly to the end rather than sitting high and then dropping.

A few seconds after the lamp is switched on, it shows a first, rough level, which the readings that follow put right.

The lamp never switches its light off by itself because the battery is low: it keeps shining until the battery is empty. In a group that syncs through the cloud, a lamp that goes off as its battery runs out does not switch the other lamps off.

Making it last until a set time

In the cloud panel you can ask a lamp - or every lamp of a group - to last until a time you choose: see Runtime. A target can be up to 10 hours away, and no shorter than the lamp lasts at full brightness with the effect it shows - for a group, the lamp with the emptiest battery. The lamp then dims itself very slowly, so you hardly notice, just enough to make it. It is never brighter than you set it, and never darker than a tenth. Each lamp goes by its own battery, so in a group a fuller lamp dims less.

The lamp keeps the time itself, so it carries on after a restart, and it needs no connection to the cloud to do it - only the time, which it gets from the internet whenever it can. When the time comes it goes back to the brightness you set. If even the dimmest light will not get there, the panel says the time is out of reach.

The lamp's page shows the time in its runtime line, and how far it has dimmed.

Switching a lamp off on its page or in the cloud panel only turns its light off - it stays on Wi-Fi and keeps using its battery. To save the battery, switch it off completely after use; how is under Lamp models.