Li-ion batteries are finding their way into more high-power applications because of their high-energy density. For battery-based systems where the typical Li-ion cell has a fully charged voltage of 4.2 V, many cells must be connected in series. That of course means that any single cell failure will disable the entire stack. Therefore, a battery control system is needed to monitor and control each battery cell’s condition. The LTC6802 multicell battery monitoring IC does all those functions, and more. It measures 12 individual battery cells, and although it targets Li-ion battery chemistry it is battery chemistry agnostic, working with NiMH and others.

Multiple ICs can be stacked without optocouplers or isolators, enabling voltage monitoring of every cell in long strings of series-connected batteries. These long battery strings enable high-power rechargeable applications for electric and hybrid electric vehicles (HEVs), scooters, motorcycles, golf carts, and UPS systems. The monitor IC measures all cell voltages, even in the presence of stack voltages over 1,000 V, within 13 ms. Each cell is monitored for undervoltage and overvoltage conditions and an associated MOSFET switch is available to discharge overcharged cells. Each IC communicates via a 1-MHz serial interface with error checking, and includes temperature sensor inputs, GPIO lines, and a precision voltage reference.