Nilar NiMH Bipolar Design
The main advantage of the bipolar design is the common and shared current collector. This important feature reduces the volumetric overhead of the current collector and inherently results in uniform current flow across the cell, thus making it ideal for higher rate discharge applications. The volumetric overhead is approximately zero in comparison to cylindrical and prismatic technologies. This gives an immediate 10% or greater volumetric density advantage. Uniform current and resistance paths also promote uniform I R heat generation. Uniform temperature generation also helps with uniform electrochemical aging, which translates to a longer cell life. The size of the surface area and thickness of the cell are directly related to the capacity of the cell.
Nilar has developed an optimal design around a safe and proven chemistry. The Nilar modules, 12V or 24V, are the building block for all Nilar battery packs.
The Nilar battery pack has four primary sub-assemblies.
- The first is the End Plate. This is a critical component to the bi-polar construction. It provides both impact protection to the cell stack as well as its primary function, uniform cell compression. This is the key to long cycle life and low resistance. There is one End Plate on each side connected via tie-rods to adjust the amount of compression.
- The second sub-assembly is the End-Plate insulator. The End-Plate Insulator prevents the End Plates from coming into contact with the Pack voltage potentials.
- The third critical component is the Heat Exchanger/ Electrical Interconnect. As the name implies, the subassembly allows for active air cooling in more extreme environments and electrically connects the adjacent module.
- The forth critical element is the module itself. In addition to the required sub-assemblies, Nilar has integrated both a temperature and pressure sensor into the battery pack construction. Along with a voltage tap per module, these signals are available for monitoring via a 15-pin connector integrated into the End-Plate assembly. The module case has an integrated wire/cable channel and cover to allow cables within the pack, thus additional volume needed for pack-to-pack interconnects is included in the actual battery pack volume.
The Nilar Battery Packs are shown in the image above. The construction is based on the Nilar Battery Module. The number of modules determine the voltage and the capacity. By arranging the batteries in parallel and series, a pack consisting of 10 modules or less has 44 unique configurations.