STLTH uses a lithium-ion polymer battery. Under hot or cold conditions, similar to other, portable electronics containing lithium-ion batteries, the battery can potentially have safety hazards. For safety purposes, charging of the STLTH device should occur at temperatures between 5°C and 25°C (41°F and 113°F). You must use a 0.5A charging method to safely and efficiently charge the STLTH device.