You don't have to worry about changing your battery again with PRO TREK's solar technology. The battery is automatically charged by light, either direct from the sun or from light sources inside. And it keeps that charge for the life of the watch. Watches with this feature have a solar cell and a special rechargable battery (secondary battery) that is charged by the electrical power produced by the solar cell.
• After a full charge, timekeeping remains enabled for up to five months.
• Storing the watch for long periods in an area where there is no light can cause the rechargable battery to run down. When stored in a dark place, the power saving function will enter a sleep mode to conserve power and energy.