Citizen E610 Instruction Manual page 62

If you frequently wear long sleeves, the fabric
u
may cover the watch and prevent it from being
exposed to light resulting in the watch becoming
insufficiently charged. It is recommended to charge
the watch once a month by exposing the dial to
direct sunlight.
[Note] Avoid charging the watch at locations that reach a high
temperature such as an automobile dashboard.
When the watch is removed, try to place it in
u
as bright a location as possible such as near
a window so that sunlight shines onto the
watch dial. This will keep the watch charged
continuously and enable it to continue to run
properly at all times.
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