from chemistry to pack
In the battery application world everyone is always looking for power vs energy density. Wanting the maximum of both. However, as we know from a comparison of power vs energy cell design it is nearly impossible to have both. In simple terms the energy cell has thicker layers of active material, thinner current collectors and … Read more
For most simple peak power calculations we will be interested in the Direct Current Internal Resistance (DCIR) value for a new cell at 50% SOC (25°C, 10s), Open Circuit Voltage (OCV) and minimum voltage. Note: this is just an estimation and this needs to be compared to the manufacturers specifications and tested values. However, as … Read more
Establishing the maximum cell discharge capability is difficult without understanding the design in detail. However, you can work towards establishing this limit with a number of measurements and calculations. The aim of this post is to describe that approach, the underlying physics, some of the measurements and calculations. First of all though we need to … Read more
What battery packs are at the pareto frontier of the Ragone plot? With a database of over 300 packs we can plot power gravimetric density vs energy gravimetric density. Koenigsegg Regara The Koenigsegg Regera is a PHEV with a combined power of 1,119kW and uses a 4.5kWh 800V liquid cooled battery. The battery is designed … Read more
Why are we moving to higher voltage packs? We know that the battery cell is not a perfect current source as it also has an internal resistance. Symbolically we can show a cell with the internal resistance as a resistor in series. Rint is the DC internal resistance, sometimes abbreviated as DCIR. The DCIR is not … Read more
India’s number one selling EV in 2022. Tata Nexon EV Prime 30.2 kWh and Max 40.5 kWh battery pack benchmarking.
Battery pack Ragone plot is power density versus energy density. There are a number of key battery metrics and this one is great to see where a design sits on the Power vs Energy Density Curve. Note that the power is the peak power of the pack available for 10s. You could also plot the … Read more
There are a number of reasons to estimate the charge and discharge current limits of a battery pack in real time: Hence this is a key function of the Battery Management System (BMS). The difficulty is that the current limits are dependent on a number of factors, for the cell alone we should consider the … Read more
Author: Anton Resing: The cathode electrodes in a lithium-ion battery are a composite of solid charge storing particles, a polymeric binder, and a conductive additive. Together, they are well dispersed in a solvent and spread like paint on a conductive substrate, an effective and pleasingly simple solution that works across various chemistries and cell designs. … Read more
Let’s look at the road vehicle power demand for the simple steady state condition. We will look at the tractive effort and power required: Aerodynamic Forces The aerodynamic forces on the vehicle are proportional to velocity squared and hence become dominant at high speed. FA is the frontal area and Cd is the drag coefficient. … Read more