Battery-Protection IC said to reduces BMS Cost by 80% in Hybrid and Electric Vehicles

Offering world-class accuracy, ultra-low power consumption, built-in safety and self-diagnostic features, and plenty of configurability, the MAX11080 solves the problems associated with safely monitoring large battery stacks. It is well suited for a spectrum of battery applications including automotive, industrial, power line, and battery backup.

From transportation to smart grids, energy storage technologies are critical to enabling the transition from fossil fuels to clean energy. The energy storage market is thus poised for unprecedented growth as green initiatives gain traction among consumers and governments worldwide. Lux Research predicts that the overall energy storage market will grow by 55% to $64 billion in 2012. The transportation energy storage market, meanwhile, will benefit from increasing demand for hybrid electric vehicles (HEVs), growing from $12.9 billion in 2007 to $19.9 billion in 2012.

The fuel tank of the future, HEV battery packs are a critical part of the drive train for next-generation transportation systems.

Though nickel-metal hydride (NiMH) was the battery chemistry of choice in the first HEVs, Li+ batteries are expected to dominate the market by 2015, as they offer a higher energy density and, therefore, longer per-charge driving range. Lux Research predicts that Li+ battery sales will jump from $6.8 billion in 2007 sales to $16.9 billion in 2012.

Yet, Li+ batteries are particularly volatile, requiring careful design and sophisticated monitoring schemes to ensure safe operation. Cell overvoltages can cause a rapid increase in cell temperature, producing a thermal-runaway condition in which gases are vented. Since HEVs often require hundreds of cells in series, the consequences of a failure are substantial: a fault in one cell could cause the entire battery pack to burn or explode.

Today battery pack designers invest a tremendous amount of time and resources to ensure the absolute safety of their stacks. Typical protection circuits employ multiple 3- or 4-channel fault monitors with costly galvanic isolators between the monitors and an assortment of analog and passive components (resistors, multiplexers, etc.). These circuits are bulky and costly, not to mention time intensive.

The MAX11080 greatly simplifies the design of high-cell-count battery packs. A 12-channel fault monitor, this device employs a proprietary capacitor-isolated daisy-chain interface to minimize component count and cost. This unique architecture allows up to 31 devices to be connected in a series stack to monitor as many as 372 cells. Meanwhile, the capacitor-based interface provides extremely low-cost isolation from one bank of batteries to the next, eliminating cascading electrical failures.

Dispatching of the need for costly isolation components, Maxim's solution consumes 75% less space than discrete designs. Altogether, it can reduce the expense of a typical battery-management system from $250 to a mere $50.