The Time Machine includes a sophisticated Power Monitor that manages charging and protects the system from over-voltage (greater than 15V input) and being connected in reverse polarity. It also protects the battery from being flattened too much, beyond which the battery could be damaged, by shutting down at 10.5V.
The Power Monitor provides system messages on its health, which can be used by those who wish to write more sophisticated Event Timing software.
When a Smart Charger or Constant Potential charger is connected to the Time Machine, the Power Monitor displays the status of the charging process.
Note that, from a dead-flat battery state, it will take about 4 hours to fully charge the Time Machines’ internal battery. The behavior you will observe during the charge process is explained below.
When the system is on charge the voltage supplied by the charger will be between 13.8 and 14.2 volts. The Power Monitor therefore sees greater than 12.6V so the top green LED will always be lit.
If current is flowing into the battery from the charger, the Blue LED will also be solidly lit.
When the battery is nearing the point where it is full, the Blue LED will start to blink. It is now on a trickle-charge and it will continue to ‘trickle’ until completely full.
When the battery is completely full, the Blue LED will extinguish because no current is flowing from the charger into the battery.
If you remove the charger before the battery is full, the Power Monitor will adjust the LEDs (downwards) to show how much charge has been achieved up to the point when you removed the charger.
So, in summary:
- If the charger is connected and turned on, and the Blue LED has extinguished, the battery is completely full.
- If the charger is connected and turned on, and the Blue LED is blinking, the battery is very nearly completely full (and is just being topped up). The smart-charger manages the top-up charge process to optimise the energy density of the battery.
- If the charger is connected and turned on, and the Blue LED is fully lit, the battery is still charging. It needs to be left on charge until at least it starts blinking, and preferably until extinguished.
- If you remove the charger its actual battery voltage will be shown by the Power Monitor.
- A full charge takes about 4 hours.
- Batteries should be topped up regularly (two-weekly or constantly) if the Time machine is not being used to extend their working life.