Every cleaning company knows that the flooded lead acid batteries used for powering floor cleaning machines will eventually need to be replaced. Purchasing new batteries can be expensive, so to save money it’s important to do the research and select batteries with the longest cycle life and the lowest cost per cycle over their lifetime. Finding the "best" set of batteries however, requires more than just comparing the ratings on the labels and prices.

To find the optimum battery for your application(s), start by determining the correct size, voltage and ampere hour (AH) capacity required for your specific floor cleaning machine.  Check the battery manufacturer's rating charts to determine which battery provides the proper voltage, AH capacity, and/or runtime that matches your application.  If you're comparing batteries from different manufacturers, it's important to carefully check the information to be sure you're comparing apples-to-apples.

Battery cycle life ratings are often based on selective data from the manufacturer. Typically, cycle life ratings are determined by the depth of discharge (DOD), which is the percentage of AH capacity discharged from the battery on each discharge.  As an example, a battery with an 80 percent DOD has only 20 percent of its capacity left. Most battery manufacturers recommend a 50 percent DOD for optimum cycle life vs runtime, but cycle life can be quoted at a wide variety of DOD ratings. This can result in what appears to show a longer cycle life for one battery type over another but may not be an accurate comparison. When comparing cycle life ratings, make sure they are rated using the same DOD.

Because test methods, temperatures, charging algorithms, and charging methods all affect cycle life, relying on printed ratings shouldn't be your only point of reference. Generally speaking, less expensive batteries may have fewer or lighter internal components (lead plates and plate construction) and may have shorter cycle life in the same application due to greater DOD.  Batteries with more or heavier plates will typically have longer cycle life but will also cost more initially. A less expensive battery might be a better choice for a company with a cleaning machine that is used occasionally, or for shorter cleaning times.  Cleaning companies or rental fleets with many cleaning machines that see heavy cycling, a higher capacity battery would benefit them by providing longer run times and lower DOD resulting in longer cycle life. This choice can save them from purchasing batteries more frequently, if the batteries also receive regular maintenance.

All that being said, when comparing battery brands to determine which one will be best, be sure to understand the differences between your application and standard test conditions.  Manufacturers test batteries in laboratory environments that are intended to simulate actual conditions encountered in a variety of applications.  These conditions may not perfectly duplicate those in your application, but by understanding the differences, the best comparison can be made.  If possible, take notes on usage patterns, charging practices, and battery maintenance frequency and compare with the battery manufacturers’ recommendations.  Ultimately you may find that one brand stands out from the others and offers you the best performance-per-dollar for your application.

This article was written and submitted by Fred Wehmeyer, Senior Vice President/Engineering U.S. Battery Manufacturing.