MTTR (Mean Time To Repair) - Mathematical calculation (or statistical average if available) of the time required to repair a device.
Discharge Rate - The rate, usually expressed in amperes, at which electrical current is taken from the battery.
Metal Hydride - An intermetallic compound or alloy in which hydrogen has been absorbed; also, the negative electrode in a nickel-metal hydride battery.
Static bypass switch - Power-electronics device that can be used to switch from one source to another without interruption in the supply of power. In a UPS, transfer is from Mains 1 to Mains 2 and back. Transfer without interruption is possible due to the fact that there are no mechanical parts and the ultra-fast switching capabilities of the electronic components.
Polarity - In electricity, the condition of being positive or negative.
Constant Power Discharge - A battery discharge regime whereby the current during the discharge increases as the battery voltage decreases.
Depth of Discharge - The ratio of the quantity of electricity (usually in ampere-hours) removed from a battery to its rated capacity.
