Balancing Performance Index
Balancing Performance Index (BPI) is a metric that combines the three most important performance parameters of any balancing system into a single number. It’s sort of like an MPG number for balancing systems.
The formula for Balancing Performance Index is:
Higher is better for efficiency and maximum balancing current, so they are in the numerator of the fraction.
For cost, lower is better – so cost is in the denominator.
The fraction is multiplied by 100 and rounded to the nearest integer so that values will be (for example) 14 rather than 0.143. This makes it easier to compare different BPI values.
BPI values for a few balancing technologies
The LTC3300 from Analog Devices and PowerPump from Texas Instruments are the two best commercially available active balancing technologies we have seen. This table shows how they compare to True Balancing and Positive Balancing.
The data from the table are plotted in this graph. True Balancing and Positive Balancing are not just incremental improvements in balancing. They are order-of-magnitude technology breakthroughs.