Battery
battery is an element that allows us to use electrical devices without wires. For the time being, in most cases, a wire is needed to charge the batteries, but already Nikola Tesla had the idea of sending electrical energy through the air. An example of wireless battery charging is inductive mobile phone chargers. In our daily life, we encounter various forms of batteries, depending on the technical characteristics or the way of storing electricity. When we hear the word battery, we first think of the cell phone battery (which is lithium-ion technology) or disposable batteries such as AA and AAA (which are zinc-carbon or alkaline).
The mentioned batteries store energy using a chemical reaction and are called chemical batteries. Unlike chemical batteries, there are other ways of storing energy, such as elevation potential energy. This method is used by reversible hydropower plants that pump water into a water tank at a higher elevation when they store energy, and when they need to release energy into the electrical grid, they release water from the tank through the pipeline to the turbine of the generator and produce electricity. (example in Croatia is RHE Velebit)
Currently, the leading application of batteries in the personal use market are mobile phones and electric vehicles such as electric cars, scooters and bicycles. Lithium-ion batteries are used for this application. Due to the high demand for lithium-ion batteries, and limited quantities of lithium raw material, a new type of battery is required for the application in question. The main requirements for the new type of batteries are lower weight/volume per capacity of stored energy and ecological acceptability of production/disposal.
Where do batteries end up after use?
Disposing of batteries after use is an environmental issue. In a world where the trend of electric mobility is growing, the amount of batteries to be disposed of is increasing. As an example, in electric cars, after the end of their life, batteries get another application, where weight per capacity is not a primary requirement. These are UPS (uninterruptible power source) devices in the buildings, batteries for ships, etc. In Croatia, the disposal of batteries is prescribed by the Ordinance on batteries and accumulators and waste batteries and accumulators NN 111/2015 (Pravilnikom o baterijama i akumulatorima i otpadnim baterijama i akumulatorima), which is harmonized with the regulations of the European Union. Through the mentioned ordinance, manufacturers are obliged to take into account their disposal during the production of batteries.
Battery technical characteristic
The relevant technical characteristics of each type of battery are:
| Name | Measuring unit | Example |
| Voltage | volt [V] | AA: 1.5VMobile phone: 5VNotebook approximately: 20 V |
| Capacity | amp hour [Ah] orwatt hour[Wh] | AA: 0.8-3 AhiPhone 13: 3.24 Ah Tesla Model 3: 50 kWh |
| Charging speed | amp [A] | punjenje mobitela od: 1-5 ATesla Model 3: 32-40 A |
| Dimension | v x d x š[mm](height x length x width) | AA diameter 14.5mm; hight 48mmTesla Model 3: 105mm x 2166.3mm x 1473.2mm |
| Weight | gram [g] | AA: 27gTesla Model 3: 480 kg |
Battery life depends on the number of charges, atmospheric conditions (temperature, humidity) in which it is placed, battery chemistry and maintenance. The nominal temperature for lithium-ion and lead-acid batteries is 25 °C, and an increase in the temperature in which the batteries work reduces their life span, the relative relationship of the mentioned phenomenon can be seen in the following figure. The number of discharges and charges also reduces the capacity of the battery. The initial number of charge and discharge cycles varies based on the type of chemical elements used to manufacture the battery, e.g. a lithium-ion battery has approximately 10 times more cycles at start than a lead-acid battery.
Lifespan
Battery maintenance is important, for example, in UPS systems where the systems in question are expected to be ready for use 24 hours a day, 7 days a week. Although most batteries are defined as maintenance-free, preventive maintenance can remove loose connections, remove corrosion, and spot a dead battery in the array before it affects the rest of the array. The standard lifespan for VRLA (valve regulated lead-acid) batteries is three to five years, lithium-ion 10 years and for batteries with soaked cells (lead) it is up to 20 years. However, expected life can vary greatly due to environmental conditions, number and depth of discharge cycles and adequate maintenance.
The IEEE (Institute of Electrical and Electronics Engineers) defines “end of useful life” for a battery as the point when it can no longer deliver 80 percent of its rated amp-hour capacity. When the battery degrades to 80 percent of its rated capacity, the aging process accelerates and the battery needs to be replaced.
As the lifespan of a chemical battery depends on the temperature, its capacity also changes in relation to the temperature. So, for example, if we leave the mobile phone in the sun, you can notice that as the mobile phone heats up, the battery itself begins to discharge faster. In the following picture, you can see how the capacity of a lead-acid battery that has been charged to its maximum capacity drops over time in relation to the temperature without a consumer connected to it.
Fire
Certain types of batteries can be a source of fire. That is why it is important that they are used as prescribed by the manufacturer. For example, lead batteries when they are being charged can create explosive gas, which is an explosive gas that has no smell or taste. For this reason, when lead batteries are used in UPS devices, it is necessary to have forced ventilation of the room. While currently the most popular type of lithium-ion batteries can self-ignite. How to behave with batteries in the event of a fire and how to extinguish the fire, the manufacturer must prescribe in the safety data sheet.
When lithium-ion batteries are used in UPS applications, they are usually protected from fire by a special system that analyzes the gasses in the space of lithium-ion batteries. The system in question can detect the gas that appears before the lithium-ion battery ignites and can prevent damage that would occur in the event of a fire. As an example of lithium-ion UPS application with a monitoring system, there are UPS systems in server rooms where a fire could irreversibly destroy the data on the servers.
Advanced rechargeable battery systems have a BMS (Battery management system) within them. The system in question can be found in electric cars, in battery systems for energy storage from renewable energy sources, etc. BMS can also prevent fire because in most cases it measures the temperature of the batteries and thus also serves as a type of fire prevention system, even if it is not its primary one purpose. The primary purpose of the BMS is to monitor the measurable values of the batteries (voltage, current, temperature, capacity, etc.) and manage the charging and discharging of the battery using the measured parameters.
Batteries can be found everywhere around us. Mass production itself has brought the price down, and the safety of batteries as a product has increased on average. Although it is considered a safe product, the battery should be used as prescribed by the manufacturer, in order to keep us and our environment safe.