This TechLetter will focus on the Battery Management System (BMS) and all associated functions. WATTALPS has developed internally its Full BMS solution adapted for demanding mobile applications, mastering the specification, the hardware design, the software development and the validation process. This will help to illustrate the different functions that a BMS must include.
The term BMS or Battery Management System is used for many different functions. This TechLetter is here to clarify all functions covered by the BMS. It is globally accepted that the BMS concerns all electronic functions, hardware or software, that manages the battery. In a lithium-ion battery, the following functions can be included in a BMS:
- Modularity and battery configuration
- Interface with the application, machine or vehicle
- Battery heating and cooling management
- Connectivity and services linked to the battery.
So as to clarify the definition of these functions, WATTALPS has defined the vocabulary here below.
Battery Safety Management (BSM)
To guarantee the safety of your product in any circumstances
The Battery Safety Management is here to keep the lithium-ion cells in a safe operating zone. As explained in our TechLetter on lithium-ion battery safety, the voltage, temperature and current of each cell of a battery pack must be kept in safe operating zone. Working outside these safe zones can result in a fire or, in certain circumstances, an explosion. Such events have therefore to be detected, treated and corrected with a high level of reliability, by using a standard development process for safety related functions (as stated in IEC 61508 or derived standards). In most cases, the safe state is obtained when the contactors are open. Nevertheless, some application may lead to dangerous situations when the contactors are open without warning. It is therefore prominent that BSMS would be synchronized with the application’s safety strategy.
To answer to these problematics, WATTALPS has developed a BSM with the following characteristics (not exhaustive list):
- The BSM is developed according to the highly demanding norm ISO 26262 dedicated to automotive electronic functional safety
- The functioning of the BSM can never be altered by other functions of the BMS
- The BSM can be adapted to the safety strategy of the application
- All core electronic components used in the safety functions are compatible with the highest automotive safety level (ASIL D)
- The BSM is specifically adapted to deal with WATTALPS’ innovative technology.
Battery Modularity Management (BMM):
To lower the development cost
To develop once for several machines and several configurations per machine
A battery management system development requires a huge effort. This is why most BMS are developed so as to be used on different battery packs. As example, the following parameters can generally be configured:
- Battery capacity
- Battery operating range (temperature, voltage, current)
- And for modular systems, battery module number and/or electrical configuration (connected in series or in parallel)
- Number of inputs/outputs
Battery Interface Management (BIM)
A turn-key solution, adapted to your specific need with reduced development cost
The BIM manages the interface between the battery and the application to which the battery is connected. The following functions are generally integrated in a BIM:
- State of Charge (SOC) of the battery, and sometimes State of Health (SOH)
- BMS wake up strategy vs application
- CAN bus communication with the application (or other equivalent buses)
- BMS modes management (standby, charge, …)
As an example, WATTALPS BIM includes the above functions and the following ones (not exhaustive list):
- Maximum current in charge and discharge sent regularly and adapted to every situation (temperature, SOC…)
- Live bit communication with application
- Flexible charger interface
- Flexible CAN bus interface
Battery Thermal Management (BTM)
A plug & play solution to simply interfaces and development
The BTM manages the temperature of the battery so as to optimize the performance, the life and the productivity of the battery (see our TechLetter “From a lithium-ion cell to a battery system” for more information):
- Heating: the BTM can activate heating of the battery so as to enable charging and high performance at low temperature
- Cooling or chilling: the BTM can activate cooling of the battery so as to enable fast charging and high power in a hot environment. If the ambient temperature can be above 45°C, a chiller may be necessary.
- Levelling cell temperatures in the battery: The performance of the battery is always limited by the weakest of its elements, it is then very important to ensure that the cell temperature is as homogeneous as possible to get an identical aging. With WATTALPS immersion cooling technology, circulating the battery dielectric fluid is an easy way to ensure a maximum temperature spread of 2°C in the battery.
- Fast charging capability: Charging is often the phase generating most heat inside the battery. It is therefore necessary to have a very efficient cooling to provide fast charging capability. WATTALPS immersion cooling technology is the most efficient cooling technology for batteries.
Battery Connectivity Management (BCM)
To master electric technology, increase customer experience and your use cases
A lot of objects are nowadays connected. For a battery in an industrial application, connectivity is a must. The Battery Connectivity Management will provide:
- Remote (Over The Air) Battery Management System software update to benefit from all new features that come with such a developing technology
- Remote (Over The Air) diagnosis for high reactivity service to the final customer
- Usage history to be able to optimize fleet management and secure a second life of the battery
- Advices to increase battery life vs usage.
WATTALPS BCM provides all these functions and even more on demand.
The BMS is a core component of your equipment, having a huge impact on the performance, the reliability and the safety of your equipment. It therefore has to be extensively tested for EMC, resistance to representative environment and endurance.
For more information on WATTALPS Full BMS and WATTALPS batteries, contact us at : email@example.com .