From the NIOSH Website:
Getting optimal performance from a powered air‐purifying respirator (PAPR) depends on the condition of its battery!
The guidance in this fact sheet will help respiratory protection program administrators, managers, and powered air-purifying respirator (PAPR) wearers understand the importance of a PAPR’s battery in assuring effective respiratory protection. The respiratory protection program administrator should assure that PAPR manufacturer recommendations for battery storage, care, usage, and disposal are addressed. However, an understanding of these requirements by managers and PAPR wearers is also beneficial to ensure personal protection.