What Battery Key Performance Indicators are?

Multiple Markets and Chemistry Types

Batteries come in many shapes and sizes, from miniature cells used to power hearing aids and wristwatches to small, thin cells used in smartphones, to large lead-acid batteries used in cars and trucks, and at the largest extreme, battery banks the size of rooms that provide standby or emergency power for telephone exchanges and computer data centers.  

Electric Vehicle Market

The rechargeable battery industry is targeting the electric vehicle market (both pure EVs and hybrids) almost to the exclusion of other markets. Battery technology developments are geared towards EVs, with other market sectors such as energy storage likely to benefit from these developments, as well as the reduction in battery costs from increasing economies of scale. 

Lithium-Ion Battery Forecasting

The predicted growth in the lithium-ion battery industry is likely to put increasing pressure on the supply chain for battery materials, both for the cathode (lithium, cobalt, nickel and manganese) and the anode (graphite). Capacity additions are on track to ensure there is sufficient supply to meet the demands of the lithium market until towards the end of the next decade. 

Power

Degradation

Degradation

Electric Power

Power capabilities of a battery start with cell anode and cathode loading to maximum current abilities of the battery system. Power capabilities from a battery are not constant discharges and charges.

Degradation

Degradation

Degradation

 Degradation

The main degradation is the breakdown of the active material (cathode material & electrolyte) due to cycling.  Damage is done on every cycle.  This degradation process can be accelerated.

Temperature

Degradation

SOC (State of Charge)

Temperature

High-temperature breaks down the electrolyte causing it to lose its ionic transfer efficiency. Voltage is the stressor and temperature is an accelerator.

SOC (State of Charge)

SOC (State of Charge)

SOC (State of Charge)

 SOC (State of Charge)

The battery is kept at a State of Charge (SOC) above 80% for a prolonged period. To improve SOC potentially battery charge voltage could be reduced gradually over time

Swelling

SOC (State of Charge)

Swelling

 Swelling

Nothing can prevent this. It is normal and expected with battery aging. But if there is a battery management system that is adaptive it could prolong battery life and avoid swelling.

Thickness

SOC (State of Charge)

Swelling

Thickness

Since the thickness of the foil and separator are fixed as the cell decreases in thickness the ratio of active material to other components decreases.

Key Performance Indicators and Battery Parameters

Price or Cost

Depth of Discharge (DoD)

Price or Cost

 Price or Cost

Short life applications (CE) tend to focus more on Price. Long-life applications (EV, ESS, UPS) concentrate more on Cost. All batteries start to degrade as soon as their formation is complete and so the price is going down too.

Energy Density

Depth of Discharge (DoD)

Price or Cost

Energy Density

Higher densities enable larger capacity cells per unit volume. This is a crucial parameter for consumer electronics and electrical vehicles. Used to distinguish technology nodes. Energy density is dependent on the thickness of the battery cell.

Depth of Discharge (DoD)

Depth of Discharge (DoD)

Depth of Discharge (DoD)

Depth of Discharge (DoD)

Calendar life is the non-operational aging effects. Used as a comparison with other technologies, not a useful measure of actual usable time. Degradation or loss of capacity over time that is not recoverable.

Capacity

Capacity

Depth of Discharge (DoD)

Capacity

Usually specified at conditions (Temp & C-Rate) that show the greatest value. Given in units of Amp-hours (Ah), used to determine overall run time based on power demands.

True Capacity: What it really is

Nameplate Capacity: What you buy

Effective Capacity: What you get to use

C-Rate

Capacity

C-Rate

 C-Rate

Relates directly to power capabilities, both in discharge and charge. Usually defined by maximum, typical, and some chemistries will note a minimum. Manufacturing could use it as Current / Nominal Capacity. Because it is easier for Capacity in Amp-hours (Ah), used to determine overall run time based on C-Rate

Safety

Capacity

C-Rate

Safety

Contingencies can be designed to mitigate specific hazards. There is no “safe” energy storage, but rather “safer.” Battery Safety design is multi-layered and starts at the cell and continues up to the whole device.

The Importance of Battery Testing

Performance and Costs

Testing to Access the Battery Value

Testing to Access the Battery Value

 Battery manufacturers are liable for their end products. They have to comply with several standards like IEEE, and they compete in the market to make the best offer in terms of both performance and cost. They need to make a well thought out decision on every aspect of the device, and so it's not surprising that they want to base their choice on the best information available. Also, most of the manufacturing is all in China, Japan or Korea. For battery cells, modules, or packs, information often comes in the form of a battery data sheet provided by the battery manufacturer. Strikingly, there is no real standard for such datasheets with time, current, voltage, capacity, and other parameters. The data you find on one Excel spreadsheet might be missing on another.  

Testing to Access the Battery Value

Testing to Access the Battery Value

Testing to Access the Battery Value

To assess the value of a battery objectively, it should be subjected to more elaborative testing. To obtain reliable results, testing activities should be carried out at dedicated battery testing laboratories with multiple measurement techniques like HPPC, DST, FUDS, and impedance spectroscopy. 

These facilities are often equipped with multiple testing devices specifically designed for testing battery cells, modules, and complete packs or even systems. Testing can include electrical, mechanical, and thermal test programs.  

Examples of measurements related to the performance, aging, and safety of batteries included common measurements, state of health and state of charge of the battery.

Common Measurements

Testing to Access the Battery Value

Data in Different Formats

  1. Capacity at different charging and discharging rates in different thermal conditions
  2. Internal resistance or impedance at different life stages
  3. Calendar and cycle life in different (operational) requirements
  4. Robustness of the battery
  5. Heat generation during charging and discharging processes
  6. Frequency, Impedance, Theoretical Capacity
  7. Voltage Drop, Average and Median Voltage
  8. The thickness of the Solid Electrolyte Interface layer (SEI)
  9. Differential capacity and voltage.

 

Data in Different Formats

Drive for New Software Platform

Data in Different Formats

 Or maybe the characteristics are not defined in the same way. This makes it very difficult to compare one solution to the next. Moreover, most of the time, datasheet values are measured in conditions that are not representative of the end application. For these reasons, it’s almost impossible for product manufacturers to estimate the real value of a battery.     Many different battery technologies are available on the market today, and each one has its own set of distinguishing characteristics. But even batteries with the same basic chemistry can exhibit substantial differences, especially when they come from different manufacturers. So Energsoft figured that it has to be a way to do an apple to apple comparison across tests, hardware, and battery types. 

Drive for New Software Platform

Drive for New Software Platform

Drive for New Software Platform

 As the drive for new solutions to address common issues like efficiency, sustainability, climate change, and user-friendliness accelerate, so too makes the demand for high-performance battery systems.   It is ranging from mobile applications such as electric bikes, cars, buses and boats, and power tools like drills, screwdrivers, and chain saws to stationary solutions that support the electricity grid and local energy systems.   Some systems consistently operate in a well-controlled and stable environment, while others need to be able to survive in harsh conditions. From this, it’s clear that manufacturers of end applications need to select the most appropriate battery technology for their specific products. You might think that’s an easy job.  

Testing Equipment

Drive for New Software Platform

Drive for New Software Platform

 Testing equipment can run standard testing protocols, as defined by the international community, but can also be programmed to perform specific testing that is more relevant to the end application. Testing equipment can run standard testing protocols, as defined by the international community, but can also be programmed to perform specific testing that is more relevant to the end application.    Whether you are working in a relevant field or you are just a battery enthusiast, you likely have a lot of questions about battery testing. What are the correct approach for testing cells, modules, and packs? Which equipment should be used? How do you process testing data to obtain results for end customers? Or how do you process data for battery modeling or the development of battery management systems (BMS)? Why are these tests being performed?  

Battery Parameters for Electrification

Primary batteries and their characteristics

Additional Information

Batteries come in many shapes and sizes, from miniature cells used to power hearing aids and wristwatches to small, thin cells used in smartphones, to large lead-acid batteries or lithium-ion batteries in vehicles, and at the most significant extreme, huge battery banks the size of rooms that provide standby or emergency power for telephone exchanges and computer data centers.   Batteries have much lower specific energy (energy per unit mass) than conventional fuels such as gasoline. In automobiles, this is offset by the higher efficiency of electric motors in converting chemical energy to mechanical work, compared to combustion engines.   A battery's characteristics may vary over load cycle, over charge cycle, and a lifetime due to many factors, including internal chemistry, current drain, and temperature. At low temperatures, a battery cannot deliver as much power. As such, in cold climates, some car owners install battery warmers, which are small electric heating pads that keep the car battery warm.   Disposable batteries typically lose 8 to 20 percent of their original charge per year when stored at room temperature (20–30 °C). This is known as the "self-discharge" rate and is due to non-current-producing "side" chemical reactions that occur within the cell even when no load is applied. The rate of side reactions is reduced for batteries stored at lower temperatures, although some can get damaged by freezing.


Recalls of devices using Lithium-ion batteries have become more prevalent in recent years. This is in response to reported accidents and failures, occasionally ignition or explosion. 


Learn more about software platform for battery data management & analytics: sales@energsoft.com

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A battery is a device consisting of one or more electrochemical cells with external connections provided to power electrical devices such as flashlights, mobile phones, and electric cars. When a battery is supplying electric power, its positive terminal is the cathode and its negative terminal is the anode.


Many important cell properties, such as voltage, energy density, flammability, available cell constructions, operating temperature range, and shelf life, are dictated by battery chemistry.


The terminal marked negative is the source of electrons that will flow through an external electric circuit to the positive terminal. When a battery is connected to an external electric load, a redox reaction converts high-energy reactants to lower-energy properties.