Lead-acid batteries for commercial uses can be made of different construction techniques, depending on the application of the battery. The most common today are calcium technology construction, in either low maintenance or maintenance free, using "flooded cells", indicating liquid electrolyte being used. These are typically inexpensive and long-lasting, with the low maintenance flooded batteries having removable caps that allow for the electrolyte to be tested and maintained.
A more traditional technology is lead antinomy construction which has become less common but has good benefits in lower charge rate commercials and some older technology vehicles. These are more suited in shallow cyclic applications or are available in "dual purpose" construction where light cycling and starting applications are combined.
More costly alternatives to flooded batteries are "valve regulated lead acid" (VRLA) batteries, also called "sealed" or AGM (absorbed glass mat) which are non spill, totally sealed and maintenance free. These usually have higher cranking capacities for their size and considered "high performance" batteries.
