Which of the following is not a requirement for electric stacker batteries?

The choice of high voltage as not being a requirement for electric stacker batteries is accurate because while voltage levels are important in ensuring the proper operation of electric motors, there is no specific minimum voltage requirement universally applicable to all electric stackers. The battery voltage needs to match the machinery's operational specifications, but it does not have to be high; it simply needs to be adequate for performance and safety.

On the other hand, low self-discharge rate is essential because batteries with lower self-discharge rates maintain their charge more effectively over time, leading to enhanced efficiency and reliability when the equipment is not in use. Maintenance-free operation is also a relevant criterion as it reduces the need for regular upkeep, making the stackers more convenient and cost-effective for operators. Lastly, a minimum capacity rating assures that the battery can deliver enough power for the intended operational tasks, ensuring that the stacker operates effectively over its expected workload.