Prolonging Life in Multiple Cells Through Cell Balancing
Analog front ends that balance cells and eliminate mismatches of cells in series or parallel significantly improve battery efficiency and increase the overall pack capacity. As the number of cells and load currents increase, the potential for mismatch also increases. There are two kinds of mismatch in the pack: state of charge (SOC) and capacity/energy (C/E) mismatch. Though the SOC mismatch is more common, each problem limits the pack capacity (mA·h) to the capacity of the weakest cell.
Battery pack cells are balanced when all the cells in the battery pack meet two conditions:
- If all cells have the same capacity, then they are balanced when they have the same relative state of charge (SOC). In this case, the open circuit voltage (OCV) is a good measure of the SOC. If, in an out-of-balance pack, all cells can be differentially charged to full capacity (balanced), then they will subsequently cycle normally without any additional adjustments.
- If the cells have different capacities, they are also considered balanced when the SOC is the same. But, since SOC is a relative measure, the absolute amount of capacity for each cell is different. To keep the cells with different capacities at the same SOC, cell balancing must provide differential amounts of current to cells in the series string during both charge and discharge on every cycle.
Read more about this topic: Lithium Polymer Battery
Famous quotes containing the words prolonging life, prolonging, life, multiple, cells, cell and/or balancing:
“We have to ask ourselves whether medicine is to remain a humanitarian and respected profession or a new but depersonalized science in the service of prolonging life rather than diminishing human suffering.”
—Elisabeth Kübler-Ross (b. 1926)
“We have to ask ourselves whether medicine is to remain a humanitarian and respected profession or a new but depersonalized science in the service of prolonging life rather than diminishing human suffering.”
—Elisabeth Kübler-Ross (b. 1926)
“I have scarcely felt greater pain in my life than on learning yesterday from Bob’s letter, that you had failed to enter Harvard University. And yet there is very little in it, if you will allow no feeling of discouragement to seize, and prey upon you.”
—Abraham Lincoln (1809–1865)
“... the generation of the 20’s was truly secular in that it still knew its theology and its varieties of religious experience. We are post-secular, inventing new faiths, without any sense of organizing truths. The truths we accept are so multiple that honesty becomes little more than a strategy by which you manage your tendencies toward duplicity.”
—Ann Douglas (b. 1942)
“Madness is locked beneath. It goes into tissues, is swallowed by the cells. The cells go mad. Cancer is their flag. Cancer is the growth of madness denied.”
—Norman Mailer (b. 1923)
“She that but little patience knew,
From childhood on, had now so much
A grey gull lost its fear and flew
Down to her cell and there alit,
And there endured her fingers’ touch
And from her fingers ate its bit.”
—William Butler Yeats (1865–1939)
“Communication is a continual balancing act, juggling the conflicting needs for intimacy and independence. To survive in the world, we have to act in concert with others, but to survive as ourselves, rather than simply as cogs in a wheel, we have to act alone.”
—Deborah Tannen (20th century)