High voltage battery storage is a power solution that saves energy by reducing peak demand. It is available in the form of individual cells - cylindrical, prismatic or pouch batteries - or modules - groups of cells connected in series and parallel. They offer the quick power delivery needed by devices that require bursts of power, such as drones and RC vehicles. These batteries also have optimized electrode materials and thicker cell walls for longer life.

Battery Control Unit

The Battery Control Unit or BCU is the heart of the Battery Energy Storage System (BESS). It oversees operations to safeguard performance and foster a healthy, reliable battery system. It also provides cutting-edge battery management capabilities to boost energy efficiency and extend battery life cycles.

Oversight includes monitoring the State Of Health (SOH) of all battery cells, data logging, leveraging cell voltage information for cell balancing algorithms and more. It also communicates with external systems and displays to provide relevant information on resident energy and other metrics.

The BCM’s core is a microcontroller, which is responsible for processing sensor data and executing battery management strategies. Thermal management is another key feature that manages operating temperatures to ensure optimal efficiency and extended battery life. The BCM may include components like heat sinks or active cooling to maintain an ideal battery temperature range. It also features electrical interconnects that facilitate power and communication between the BCM and external systems.

Battery Discharger

In low to moderate rate applications the High voltage battery discharger curve remains on a flat plateau through most of its useful life. For high-rate discharges (for example 4C), the voltage behavior is quite different.

This is due to the fact that a large portion of the capacity remains unconverted lead pastes in the electrodes. During discharge these pastes are converted to active material by the electrolyte solution. This process requires a substantial current, which can be very draining on the battery. This results in an end-of-discharge voltage that is lower than for low-rate discharges. After the load is removed the battery voltage gradually recovers to a value that may be higher than its nominal voltage. A disconnect circuit is often provided to prevent reapplying the load after the battery has recovered its full capacity. This circuit should be designed with some hysteresis to prevent accidental battery disconnection under load. The BMU monitors individual cell voltage and cell group temperature for up to 12 or 24 cells in a module. The BMU also contains passive cell balancing circuitry controlled by the BCU to bring each battery and module to the same voltage level.

Battery Tester

Battery testers are designed to provide an indication of battery state and performance. They usually operate by applying a load to the battery and then analyzing its response. They are typically easy to use and often come with a clear display or gauge of results.

Domestic battery testers are commonly used for rechargeable cylindrical batteries such as AA, AAA, and 9V PP3 batteries. When a conductive ink in the tester makes contact with both the positive and negative terminals, it releases a current that can be measured. The resulting colour change of the gauge indictates the battery’s state of charge.

These types of battery testers only measure current, and may not be accurate for all battery chemistries. Alkaline and lead-acid batteries, for example, typically show more consistent readings, while lithium batteries tend to experience larger drops at certain specified charge levels. Another method is to use a hydrometer, which requires opening the vent caps and removing electrolyte from the battery.

Battery Maintenance

Whether on-shelf or in use, batteries need periodic charging and cleaning to keep them at peak performance. Batteries self-discharge at a rate that varies by battery chemistry and extreme temperatures significantly reduce their capacity and lifespan.

A schedule for inspecting batteries should include checking the open circuit voltage with a digital voltmeter in a resting state, before and after charging them. This is important because a reading taken while the batteries are in service can be inaccurate due to their current consumption.

Battery terminals should be cleaned frequently, using a mixture of baking soda and water, or post and clamp cleaner. Corroded terminals waste energy and prevent the flow of electrical currents. Battery trays should also be cleaned periodically, and the mounting hardware checked for looseness. Ensure that all workers involved in battery maintenance have the proper personal protective equipment per manufacturer recommendations; this typically includes eye protection, rubber gloves, and long sleeves to cover any metal parts of the body.

The Bottom Lines

High rate discharge batteries provide quick bursts of energy, ideal for devices requiring instant power. They feature optimized electrode materials, high C-rate values and physical characteristics that maximize energy density. HV battery cells are found in a variety of forms from individual cylindrical, prismatic or pouch cells to modules and batteries - groups of cells connected in series and parallel.