from chemistry to pack
Jerry Wan’s post (right) asks whether cell design has a “golden ratio” for aspect ratio. He concludes that there isn’t a universal one, and that’s right. But the reasons are worth working through, because the best shape changes completely depending on where the tabs are and which edge the heat leaves by. A ratio that … Read more
The cell to cell temperature gradient in a battery pack will limit the performance and lifetime. However, there will always be a cell temperature gradient and a cell to cell temperature gradient. It is very difficult not to have if we are rejecting or absorbing heat. The cell to cell temperature differences can be due … Read more
Whatever the cell format and however we cool it there will be a temperature gradient. This is described by Fourier’s Law of Conduction. An empirical law stating that the rate of heat flow is directly proportional to the temperature gradient and the area of heat transfer, and inversely proportional to the thickness of the material. … Read more
Prismatic cells are typically surface-cooled when used in real world scenarios, and we have observed a growing demand for testing methods that align to this. Thus we have been investigating the best methods for replicating the conditions a battery may be used in. Recently, we conducted a surface cooling test on a 314Ah prismatic cell. … Read more
The 2022 Kia EV6 is an interesting vehicle, perhaps mostly because of the specifications around the battery pack. Specifications that have been achieved with some small steps in design. This platform is shared with the Hyundai Ioniq 5. The 2021 Hyundai Ioniq 5 pack had 30 modules and a total of 72.6kWh. In this design … Read more
Battery thermal management (BTMS) systems are of several types. BTMS with evolution of EV battery technology becomes a critical system. Earlier battery systems were just reliant on passive cooling. Now with increased size (kWh capacity), Voltage (V), Ampere (amps) in proportion to increased range requirements make the battery thermal management system a key part of … Read more
Auxiliary systems power consumption in a vehicle especially an electric vehicle have a big effect on the vehicle range. The Range is decided by the battery capacity in kWh. Battery capacity is primarily used to provide traction power through AC or DC motor. Efficiency of motor, drivetrain and battery can tell you how much power … Read more
Building on the Tesla fast charge thermal model that was discussed in the Siemens post: Race to the clouds: Battery thermal behavior simulation of a Tesla Model 3. This article looks at the cooling system and impact of a change in cooling direction. Starting with the model and the original Fast Charge Scenario. Fast Charge … Read more
The cells in a battery pack weigh a lot, but everything other than cells also weighs a good percentage of the total. For a 100kWh battery pack there is 175kg to 275kg of: We could just look at Cell to Pack Mass Ratio as this is a metric used to establish how efficient a particular … Read more
What are the key parameters for dielectric fluids as used in a battery pack? We take a look at a few reference papers to build an initial list. There are many options for cooling batteries. However, dielectric immersion cooling is seen as perhaps the ultimate high performance cooling method for battery cells. In this particular … Read more