Understanding the Functionality of Battery Management Systems

Battery management systems are commonly known for safeguarding battery cells. They continuously monitor while conveying vital data on battery performance. Their application includes mobile phones, medical equipment, battery packs and vehicle battery management systems.

According to Battery University, the system performs various functions that can be summarized as outlined below:

  • Guarantee safety and longevity of batteries. It is crucial for all Li-ion batteries.
  • Ensures state-of-function by maintaining the state of charge (SOC) and state of health (SOH)
  • Act as a point of caution and service prompt. It may monitor temperature and cell calibration.
  • Act as the end of life sensor for capacity set threshold.

Guarantee safety and longevity of batteries

Lithium-based ion battery cells consist of two sets of design, charging and discharging. Overcharged cells may end up damaged or overheated. Worse off, they can explode and burst in flames as has happened in recent cell phone launches. Besides, discharged cells below the pre-set capacity level could end up permanently impaired, mostly configured to five percent (5%) of total set capacity.

However, to guarantee battery safety while enhancing its lifespan, a safeguarding chip is installed in the battery management system, referred to as Li-ion protector. This ensures maximum protection against under-voltage and overvoltage of the battery cells.

Upon detecting battery overvoltage, due to overcharging, the protector disconnects the safeguarding chip-switch to prevent any further charging of the cells. The chip-switch closes once the battery voltage levels are below the set conditions. Similarly, during discharge, the chip will open the switch preventing further discharging of the cells. All these safeguarding measures ensure prolonged battery life.

Ensure the State of Function

Battery power meters play a vital role in the energy management of devices by users. The best example is battery meters fitted in laptops. The meter system measures and conveys the percentage of charge in the cells before the next charging prompt. Advanced laptop models have monitors installed to measure the rate of consumption over a certain period. The results of the analysis are made readily available for users’ consumption.

Measurement of percentage of charge available for use in the cells, state of charge (SoC), is presented through a digital platform. Portable gadgets include System Management Bus platform with the automotive sector using the Controller Area Network to display the SoC to the users. A local Interconnect Network currently has planted its roots in the locomotive industry.

However, SoC remains inadequate without the battery cell’s fades tracker. A battery sustains its full capacity for a short period of use after manufacture. However, capacity levels are not sustainable with continuous use. Importantly, capacity measures the state of health (SoH)

Act as Point of Caution and Service Prompt

Supervisory systems were first fitted on stationary batteries to monitor cell voltage over a certain period. The system uses battery management systems to monitor the temperature levels of battery cells and provide real-time analysis to the users. The systems can isolate and report the slightest temperature drop or sudden rise. Rapid rise or decline in temperature indicates a problem in the cells.

The measurement works to reveal individual cell resistance, corrosion, and separation of plates prompting the user to undertake battery service as recommended.

Act as the end of life sensor for capacity set threshold.

The battery management system works like a pro in identifying irregular battery performance. However, building a BMS reliable enough to measure capacity fade levels of battery cells below the seventy percent (70%) threshold in use proves a hard nut to crack. The inability to detect fade drops below 70% shortens the lifespan of the battery.

Current BMS can only detect cell inconsistency in voltage variance and internal resistance. The faults emanate from detected cell imbalances. The ability remains present within the set capacity levels between 100% and 70%. The battery gets a clean bill node of use while it may have dropped to levels below 50% undetected by the system.

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