To know if your battery is almost empty, there are various ways to check the charge status. Here are some methods you can use:

1. Battery Indicator: Many devices and vehicles have a built-in battery indicator, such as a battery icon on a display or an LED light. This indicator usually shows the current charge status of the battery, for instance using bars or percentages.

2. Measuring Voltage: You can measure the voltage of the battery with a voltmeter or a multimeter. Refer to the specifications of your battery or the device's manual to determine which voltage is considered "empty." A significant drop in voltage can indicate an almost empty battery.

3. Device Performance: If the battery is almost empty, the device may perform less well than normal. For example, you might notice that the speed of an electric scooter or the power of an electric tool decreases. This can be an indication that the battery is almost empty.

4. Charging Time: If you charge the battery regularly, you can get an idea of the usual charging time. If the charging time becomes significantly shorter, this may indicate that the battery is almost empty and has less capacity to charge.

It is important to note that the precise way in which the charge status is indicated can vary depending on the type of battery and the device in which it is used. Always refer to the manual or instructions from the battery or device manufacturer for specific information about checking the charge status and interpreting the results.