Canon SPEEDLITE EL-1 Advanced User's Manual page 29

For safety reasons, recharging in low temperatures (5-10°C / 41-50°F) will take longer
(up to approx. 4 hr.).
The battery is not charged at the time of purchase.
Please charge it before use.
Charging should be done on the day of use or a day earlier.
Even when charged and stored, the capacity of the battery gradually decreases due to
natural discharge.
When charging is completed, remove the battery and disconnect the plug from
the outlet.
You can know whether the battery is fully charged or depleted by the mounting
direction of the protective cover.
The attached protective cover can change its color when seen through the window
< > of the protection cover depending on the mounting direction. You can judge the
status of the battery by pre-determining the charged and used colors.
Remove the battery when not using the flash.
If the battery is left in the flash for a long period of time, a small amount of current will
flow, resulting in over-discharging and shortening the battery life. Attach the battery
protection cover and store it. In addition, the performance may be reduced when the unit
is stored with the battery fully charged.
The charger can be used overseas too.
The charger is compatible with a household power supply of 100V to 240V 50/60 Hz.
Use a commercially available power plug conversion adapter that is compatible with
your country or region. Do not connect the charger to an electronic transformer for
overseas travel as this may damage the charger.
If you can't use it immediately after charging it fully, this means the battery has
reached the end of its life.
Check the battery deterioration before purchasing a new battery.
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