Battery, Operation guide 2790 – Casio 2790 User Manual

Page 3

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Operation Guide 2790

3

Level 1

19 hours

93 hours

189 hours

Level 2

20 hours

100 hours

202 hours

Level 4

Level 3

46 hours

230 hours

– – –

Approximate Exposure Time

Exposure Level
(Brightness)

Outdoor Sunlight (50,000 lux)

Sunlight Through a Window
(10,000 lux)

Daylight Through a Window on a
Cloudy Day (5,000 lux)

Power Saving on
indicator

Elapsed Time in

Dark

About one hour

6 or 7 days

Display

Blank, with
PS flashing

Blank, with
PS not flashing

Operation

Display is off.

All functions and analog timekeeping are
enabled.

Timekeeping is maintained.

Display is off.

Beeper is disabled.

Analog timekeeping is disabled, with
hands positioned at 12 o’clock.

Digital timekeeping is maintained.

Battery

This watch is equipped with a solar cell and a rechargeable battery (secondary
battery) that is charged by the electrical power produced by the solar cell. The
illustration shown below shows how you should position the watch for charging.

Example: Orient the watch so its

face is pointing at a
light source.

Note that charging efficiency
drops when any part of the
solar cell is blocked by clothing,
etc.

The illustration shows how to
position a watch with a resin
band.

Important!

Storing the watch for long periods in an area where there is no light or wearing it in
such a way that it is blocked from exposure to bright light can cause rechargeable
battery power to run down. Be sure that the watch is normally exposed to bright light
whenever possible.

This watch employs a solar cell that converts light into electricity, which charges a
built-in rechargeable battery. Normally, the rechargeable battery should not need
replacement, but after very long use over a number of years, the rechargeable
battery may lose its ability to achieve a full charge. Should you notice problems with
getting the rechargeable battery to a full charge, contact your dealer or CASIO
distributor about having the rechargeable battery replaced.

The rechargeable battery should be replaced with a CASIO-specified ML2016
battery only. Other rechargeable batteries can cause damage to the watch.

All data stored in memory is deleted, and the current time and all other settings
return to their initial factory defaults whenever battery power drops to Level 4 and
when you have the battery replaced.

Turn on the watch’s Power Saving function and keep it in an area normally exposed
to bright light when storing it for long periods. This helps to keep the rechargeable
battery from going dead.

Battery Power Indicator
The battery power indicator on the display shows you the current status of the
rechargeable battery’s power.

Solar cell

Level

1

2

3

4

Battery Power
indicator

or

(Charge Soon Alert)

Function Status

All functions enabled.

All functions enabled.

Beeper tone, display
illumination, display, and
buttons are disabled. Though
the hands of the watch do not
move, time continues to be
kept internally.

All functions, including
timekeeping, are disabled.

Battery power indicator

If the MID indicator starts to flash a few minutes after the display is illuminated or
after the beeper sounds, it means that the battery level is about to go from Level 2
to Level 3. If this happens, avoid using display illumination and the beeper, and
expose the watch to bright light to charge its battery.

The flashing LO C indicator at Level 3 tells you that battery power is very low, and
that exposure to bright light for charging is required as soon as possible.

At Level 4, all functions are disabled and settings return to their initial factory
defaults. Functions are enabled once again after the rechargeable battery is
charged, but you need to set the digital time and date after the battery reaches
Level 3 (indicated by flashing LO C indicator) from Level 4. You will not be able to
set any of the other settings until the battery reaches Level 2 (no LO C indicator)
after dropping to Level 4. When the battery returns to Level 2, the watch will
automatically adjust the analog time setting to match the digital time.

Leaving the watch in direct sunlight or some other very strong light source can
cause the battery power indicator to temporarily show a reading that is higher than
the actual battery level. The correct battery power indicator should appear after a
few minutes.

If you use illumination or any of the alarm functions a number of times during a short
period, the recover (R) indicator appears on the display and the following operations
become disabled until battery power recovers.

Illumination; Beeper tone
Manual adjustment of the analog time in the Hand Setting Mode

After some time, battery power will recover and the recover (R) indicator will
disappear, indicating that the above functions are enabled again.

Charging Precautions
Certain charging conditions can cause the watch to become very hot. Avoid leaving
the watch in the areas described below whenever charging its rechargeable battery.
Also note that allowing the watch to become very hot can cause its liquid crystal
display to black out. The appearance of the LCD should become normal again when
the watch returns to a lower temperature.

Warning!
Leaving the watch in bright light to charge its rechargeable battery can cause it
to become quite hot. Take care when handling the watch to avoid burn injury.
The watch can become particularly hot when exposed to the following
conditions for long periods.

On the dashboard of a car parked in direct sunlight

Too close to an incandescent lamp

Under direct sunlight

Charging Guide
After a full charge, timekeeping remains enabled for up to about 11 months.

The following table shows the amount of time the watch needs to be exposed to
light each day in order to generate enough power for normal daily operations.

Exposure Level (Brightness)

Outdoor Sunlight (50,000 lux)

Sunlight Through a Window (10,000 lux)

Daylight Through a Window on a Cloudy Day (5,000 lux)

Indoor Fluorescent Lighting (500 lux)

Approximate
Exposure Time

5 minutes

24 minutes

48 minutes

8 hours

Since these are the specs, we can include all the technical details.

Watch is not exposed to light

Internal timekeeping

Display on 18 hours per day, sleep state 6 hours per day

1 light operation (1.5 seconds) per day

10 seconds of alarm operation per day

Stable operation is promoted by frequent charging.

Recovery Times
The table below shows the amount of exposure that is required to take the battery
from one level to the next.

The above exposure time values are all for reference only. Actual required exposure
times depend on lighting conditions.

Reference

This section contains more detailed and technical information about watch operation.
It also contains important precautions and notes about the various features and
functions of this watch.

Power Saving Function
When turned on, the Power Saving function automatically
puts the watch into a sleep state whenever it is left in an
area where it is dark while the Timekeeping Mode or Dual
Time Mode is selected.

The watch does not enter the sleep state while the
Stopwatch Mode is selected.

The watch does not enter the sleep state while the
Alarm Mode or Hand Setting Mode is selected.
However, if you leave the watch in either of these
modes, it will automatically revert to the Timekeeping
Mode after a preset amount of time. After that it will be
able to enter the sleep state.

The table below shows how watch functions are affected by the Power Saving
function.

Wearing the watch inside the sleeve of clothing can cause it to enter the sleep state.

The watch will not enter the sleep state between 6:00 AM and 9:59 PM. If the watch
is already in the sleep state when 6:00 AM arrives, however, it will remain in the
sleep state.

To recover from the sleep state

Perform any one of the following operations.

Move the watch to a well-lit area.

Press any button.

Angle the watch towards your face for reading.

To turn Power Saving on and off

In the Timekeeping Mode, hold down

C

for about two

seconds to toggle Power Saving on (PS indicator
displayed) and off (PS indicator not displayed).

Note that pressing

C

also toggles between 12-hour

timekeeping and 24-hour timekeeping.

The Power Saving on indicator (PS) is on the display in
all modes while the Power Saving is turned on.

Auto return features

If you leave a screen with flashing digits for two or three minutes without performing
any operation, the watch automatically saves anything you have input up to that
point and exits the setting screen.

The watch automatically returns to the Timekeeping Mode if you do not perform any
button operation for two or three minutes in the Alarm or Hand Setting Mode.

Scrolling

The

C

button is used to scroll through setting screen data on the display. Holding

down this button during a scroll operation scrolls through the data at high speed.

Illumination Precautions

The illumination provided by the light may be hard to see when viewed under direct
sunlight.

Illumination automatically turns off whenever an alarm sounds.

Frequent use of the light shortens the battery operating time.

Note that illumination is disabled while the analog hands are in motion to adjust in
accordance with a change made to the digital time setting in the Timekeeping Mode.

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