Casio 2790 Battery, Reference, Auto return features, Scrolling, Illumination Precautions

Operation Guide 2790

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	Solar cell
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.

•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.

Exposure Level	Approximate Exposure Time
(Brightness)
	Level 4		Level 3	Level 2	Level 1
Outdoor Sunlight (50,000 lux)	46 hours			20 hours	19 hours
Sunlight Through a Window	230 hours			100 hours	93 hours
(10,000 lux)
Daylight Through a Window on a		– – –		202 hours	189 hours
Cloudy Day (5,000 lux)

•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.

• 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.

	Level	Battery Power	Function Status
		indicator
Battery power indicator	1		All functions enabled.
	2	or	All functions enabled.

Power Saving on indicator

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.

	Beeper tone, display
	illumination, display, and
3	buttons are disabled. Though
	the hands of the watch do not
	move, time continues to be
(Charge Soon Alert)	kept internally.
4	All functions, including
	timekeeping, are disabled.

•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)	Approximate
	Exposure Time
Outdoor Sunlight (50,000 lux)	5 minutes
Sunlight Through a Window (10,000 lux)	24 minutes
Daylight Through a Window on a Cloudy Day (5,000 lux)	48 minutes
Indoor Fluorescent Lighting (500 lux)	8 hours

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

Elapsed Time in	Display	Operation
Dark
About one hour	Blank, with	• Display is off.
	PS flashing	• All functions and analog timekeeping are
		enabled.
		• Timekeeping is maintained.
6 or 7 days	Blank, with	• Display is off.
	PS not flashing	• Beeper is disabled.
		• Analog timekeeping is disabled, with
		hands positioned at 12 o’clock.
		• Digital timekeeping is maintained.

•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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