Lead-acid batteries have limited range, long recharging cycles, and produce inconsistent voltages, which impact the productivity and performance of MHE. In high volume operational environments, a lead-acid battery can last, at most, 8 hours before requiring a recharge or replacement. Because of the long recharging cycle (batteries require 8 hours to charge and 8 hours to cool off in a three-shift operation), multiple chargers are required for the MHE fleet. Lead-acid batteries also lose power as they discharge throughout a shift, decreasing MHE performance and resulting in lost productivity through a reduction in the amount of mail or equipment moved in a given period of time.
Lead-acid batteries also pose environmental health and safety risks. They contain sulfuric acid, which is an Extremely Hazardous Substance (EHS) according to the Environmental Protection Agency (EPA) Emergency Planning and Community Right-to-Know Act (EPCRA). These batteries present a health and safety risk due to the corrosive nature and chemical properties of sulfuric acid. Lead-acid batteries can cause chemical burns and expose employees to hazardous materials (lead and sulfuric acid) and dangerous gases during operation and maintenance.
Installing the hydrogen fuel cell system provides the USPS with operational, financial, and environmental advantages over the lead-acid battery system. The system increases the productivity of MHE and MHE operators, and saves money by reducing the time and frequency required to refuel or charge MHE. This eliminates the need to purchase lead-acid batteries every three years, and reduces MHE maintenance costs from inconsistent voltages.
— Energy Initiatives,
Office of Sustainability, 4-13-17