Battery Management System
Batteries are the heart of an Electric Vehicle but the Battery Management System is more like the brain which keeps the Heart pumping out electricity to the Motor safely and at required output. Electric
safety
Temperature Limits of a Battery
There are a number of temperature limits of a battery cell, some harder limits than others. It is worth understanding these in general before looking at a specific cell. These temperatures will change with chemistry and by cell manufacturer, therefore, it is really important to use the limits as advised by the manufacturer. In addition … Read more
EUCAR Hazard Levels
The EUCAR Hazard Levels define the outcome of cell level safety testing. These levels are normally used to describe the outcome of tests such as overcharge as part of the cell specification. Description Description Classification Level & Effect 0 No effect No effect. No loss of functionality 1 Passive protection activated No defect; no leakage; … Read more
Thermal Runaway vs Electrical Energy
The energy released during Thermal Runaway versus the electrical energy stored in a battery. The energy released during Thermal Runaway (TR) versus the stored electrical energy. A number has been bandied around for a long time that the energy released in a TR event was 2 to 6 times the electrical energy stored in the … Read more
EV Current Sensors: The Basics
EV current sensors are basic components. They perform two major tasks. They help us to know how much energy we use. Also, the second task is avoiding overcurrents. Therefore, current sensors are a major sub-systems of a battery design. EV current sensors can include resistive or magnetic elements based on their structure. We use these … Read more
Cell Internal Short Circuits
Although very rare, cell internal short circuits are a leading cause of battery thermal runaway. They are a major safety issue for any application of a battery pack. Hence there is a requirement to prevent them and to detect them. Common hazards of battery thermal runaway include toxic off-gassing, smoke, fire, and even an explosion. … Read more
How to select EV Fuses
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
How to select EV Contactors
Contactor selection is an iterative process that includes consideration of system specifications as well as failure scenarios. Most of the contactor manufacturers share necessary information in datasheets. Thus, a wise approach would be making a comparison table to cover basic specifications like thermal and mechanical initially. System Specifications After pre-selection based on datasheet values, we … Read more
Contactors: The Basics
Contactors are electromechanical switches. They control the connection of battery Cells to the external electrical circuit. A contactor has an electromagnetic circuit. It simply works like a solenoid to push moving contact [1]. Therefore, contactors have two different electrical circuits inside: one is for actuation and the other one is to carry currents during the … Read more
Fuses: The Basics
Fuses are protection devices that protect electrical circuits against undesired high currents. We can use passive fuses and pyro fuses in battery design. Passive Fuse Passive fuses break the circuit only as a result of high currents for a certain time. They have a weak internal structure as a melting element. During high currents above … Read more