Replaced the battery in my Casio Pathfinder1500. After you replace it, you need to connect the + contact as shown on the watch metal plate with the negative side of the battery by the use of metal tweezers. This resets the watch. Also need to set altitude & re-calibrate the compass. Consult watch manual for instructions. Working perfectly & keeps a full charge.

After installing the battery on my GShock GW-500A, I let it charge under UV light for 24 hours. It read "medium" charge and I thought it would bump up to high after wearing it for the day. NOPE. Half way through the day I looked for the time annnnnd DEAD. The watch was completely dead. Back to square one disassembling to send back. Bummer.

My 10 year-old GW-800 g-shock's battery finally stopped retaining the charge so it was time to replace the battery. I would recommend watching "How to Change a CTL1616 Rechargeable Watch Battery in a Casio G-Shock" video on youtube.
Removal of the battery was a bit tricky and the new battery fit perfectly. The watch's main component popped out of the case for me as I was removing the old battery. After attempting to align it back properly into the case about 3 times, the buttons are functional, speaker works and most importantly, the battery works! The battery's charge level shows "H" all the time.

The battery on my solar rechargeable watch had died after 11 years of use and it wouldn't keep a charge. I contacted the Casio Service Center to buy a new battery for it and they wouldn't sell me one, but they couldn't tell me why. It would have cost me big $$ to send the watch back and have to pay their service charge to have them replace the battery and ship it back to me and no telling how long that would take. I found this exact same battery on Amazon, bought it at a reasonable price, received it in two days and took it to my watch repair store. They had a repairman that had experience with this type of battery. He installed it, returned it to me a few days later and my watch works just like the day I bought it and charges beautifully. All I had to do was reset the functions to my taste. I don't know what is going on with Casio that they won't sell the battery, but to a competent watch repairman, this is certainly not Rocket Science.

BATTERY PRETTY MUCH DEAD ON ARRIVAL. STATES I NEED TO "CHARGE" ON MY MUDMASTER, BUT AFTER CHARGING IT UNDER A LED LIGHT FOR OVER 24 HOURS AND UNDER DIRECT UV SUNLIGHT FOR OVER 24 HOURS, IT STILL READS "CHARGE".