Archive for Casio solar pro trek battery CTL1616

How to change the battery on a Casio ProTrek Solar Powered watch

Posted in Uncategorized with tags , on December 30, 2008 by gtouser

In my opinion it shouldn’t be necessary to change the battery on a solar powered watch for obvious reasons but searching on teh internet it seems that these watches are prone to battery failure. The battery is a Cobalt Titanium Lithium Rechargeable battery CTL1616 made by Panasonic and also SONY. Mine has already been replaced under waranty but when it failed again less than two years later Casio wanted more to change it than I can buy a new watch so I decided to do it myself.
First remove the strap by using a pin to compress the two pins in the usual way for any watch.

Now remove the four screws and take the back off


remove the rubber sheet to expose the battery cover, note this is not the battery but a sheet metal cover


Inser a needle into the cavity at the 12 o clock position and release the metal clip so the cover can be lifted and the battery slid out as shown in next photo


Slide the battery out. My battery had brown ooze at the join which doesn’t look healthy.


Put your new battery in observing polarity.

I found a link online for a comany that can supply them it is or get there from  BTW I have no connection with either company, information only.


Update : –  I fitted a non-rechargeable battery last October cost 20 pence on ebay (pack of 5 for £1) and it is still going strong with a “full charge” showing on the display after nearly a year of use

Summary: I wouldn’t bother with the expensive rechargeable CTL1616 when you can get this performance from a throwaway replacement cell.

Here is some data for the battery below for those that are interested





Nominal Capacity 18mAh


Nominal Voltage 2.3V


Standard Discharge Condition 1.0mA


Standard Charge Condition
(Constant Voltage and Constant Current Method)
Voltage 2.6V
Current 3.0mA
Time 24h


Cathode Active Material Lithium Cobalt Oxide


Anode Active Material Lithium Titanium Oxide


Energy Density per Volume 129Wh/l


Energy Density per Mass 38Wh/kg


Cycle characteristics(100%DOD)* More than 100 cycles


Operating temperature range -10~60�C


Weight 1.1g
* More than 70% capacity
discharge capacity versus load current

discharge capacity versus load current

Charge Characteristics

Charge Characteristics

more graphical data in the gallery below