Canon EOS-1D X Mark II DSLR Camera (Body Only) - Manual (Page 44)

Charging the Battery
44
The battery charger can also be used in foreign countries.
The battery charger is compatible with a 100 V AC to 240 V AC 50/
60 Hz power source. If necessary, attach a commercially-available
plug adapter for the respective country or region. Do not attach any
portable voltage transformer to the battery charger. Doing so can
damage the battery charger.
Check the battery performance.
While the battery is recharging, press the charger’s
<
PERFORMANCE > button to check the battery’s performance level
indicated by the charge level indicator.
: Battery’s recharge performance is fine.
: Battery’s recharge performance is slightly degraded.
: Purchasing a new battery is recommended.
If the battery becomes exhausted quickly even after being fully
charged, the battery has reached the end of its service life.
Check the battery’s recharge performance (p.44, 484) and purchase
a new battery.