from chemistry to pack
Relaxation in bolted busbar joints can be a significant battery durability issue. As joints relax the resistance of that joint increases, resulting in larger voltage drops and excess heat generation in the joint. The relaxation of the joint can be the result of a number of mechanisms: Stress Relaxation Stress relaxation is a function of time, … Read more
How can we go about maximising pack energy density? What can we look at to reduce the mass and volume? Where are the opportunities given a defined cell? A great example of shrinking the size of a battery pack is the Mercedes Vision EQXX research car. The advantage they had was a much more energy … Read more
The Electrical Contact Resistance at a metal to metal contact is primarily governed by: The surface structure can be further described by the surface flatness, surface oxidation and water adsorption. These joints in a battery pack will either be welded or bolted. Initially the easiest to think about is the bolted busbar joint. The bolt … Read more
When we connect cells in parallel to increase the capacity we might also want cell level fusing. This fusing being by definition designed to disconnect a cell that for some reason is sinking or delivering high currents. The fusing can be inside the cell and sealed or external to the cell, sometimes both internal and … Read more
The fuse selection procedure is very similar to contactor selection and complementary parameters help to select EV fuses. Fuse datasheets include breaking current-time characteristics. Some of the fuse manufacturers also provide thermal and mechanical characteristics. Thermal and Mechanical Specifications Fuses are simple busbars with melting elements inside. Therefore, the initial step is always to define … Read more