Overcoming battery charging
imbalance 12-volt devices must be connected through an equalizer (or a DC-toDC converter) in order to equally discharge the battery pack.
By Brad Bisaillon
W
Overcoming battery charging imbalance will lengthen battery life.
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BUSRIDE | SE P T EMBER . 2013
ith the emergence of advanced electrical systems in today’s bus designs, reliance on batteries to power them has become increasingly important. These continually evolving electrical subsystems are putting a tremendous strain on the batteries that power them, so effective management of the battery bank’s charge and discharge characteristics are imperative to extending the overall life of deep-cycle AGM batteries. Proper balancing of a bus’ electrical load can mean the difference between achieving a battery’s rated lifecycle or its premature failure. While bus original equipment manufacturers (OEM) in both North America and Europe build 24-volt platforms (2 X 8D batteries or 4 X Group 31 AGM batteries), those in North America follow a commonly accepted practice of installing accessory devices that are only 12-volt. These 12-volt devices include fare boxes, fire suppression systems, and security and surveillance equipment. They must be connected through an equalizer (or more favorably via a DC-to-DC converter) in order to equally discharge the battery pack. Unfortunately, it is also a common practice to directly connect some of these accessory devices to only the 12-volt power supply, or half of the battery bank, because some of these devices are required to remain powered even when the master disconnect is off. This causes busride.com