Canon MARK IV User Manual (en)

Charging the Battery
Recharge the battery on the day before or on the day it is to be used.
Even during storage, a charged battery will gradually discharge and 
lose its power.
After recharging the battery, detach it and unplug the power 
cord from the power outlet.
When not using the battery and charger, attach the protective covers.
Use the battery in an ambient temperature range of 0°C - 45°C / 
32°F - 113°F.
To attain best battery performance, an ambient temperature of 10°C - 
30°C / 50°F - 86°F is recommended. In cold locations such as snowy 
areas, battery performance and operation time may temporarily decrease.
When not using the camera, remove the battery.
If the battery is left in the camera for a prolonged period, a small 
amount of power current is released, resulting in excess discharge 
and shorter battery life. Take out the battery from the camera and 
attach the protective cover before storing. Storing the battery after it 
is fully charged can lower the battery’s performance.
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 
<PERFORMANCE> button to check the battery’s 
performance level indicated by the Charge level indicator.
   (Green) : 
Battery performance is fine.
(Green) :
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.247) and purchase a new battery.
Tips for Using the Battery and Charger