# Electronic Life Cycle Monitoring System for Various Types of Lead Acid Batteries
## 1 Introduction  
The increasing number of people, industrial production and development require more and more energy resources. Electricity is the most common type of energy used by both ordinary consumers and industries. Various resources are used to obtain electricity: fossil fuels such as oil products and gas; nuclear fuel and renewable energy sources (solar energy, wind energy, green hydrogen, etc.) [1; 2; 3]. According to the directives of the European Union, until 2035, the production of cars with internal combustion engines will have to be completely stopped, and only cars with electric motors will be used. Hence, the demand for electricity will only increase over time [4; 5; 6]. As the demand for electricity grows, reliable energy storage systems will become increasingly necessary. Since renewable energy often depends on weather and climate conditions, which are not stable, for this reason, power peaks appear in the general electricity transmission and distribution network, which need to be compensated. Various electrical energy storage systems consisting of high-capacity (200 MWh and more) Li-ion-based batteries are increasingly being used to level up the power imbalances. An increasing number of households are installing solar power plants, which not only supply electricity to the general distribution network but also charge electricity storage systems installed in residential houses or other private objects [7; 8; 9; 10]. When using off-grid-type solar power plants, it is necessary to use an electrical energy storage system, which is usually made using Li-ion batteries or batteries made on the basis of lead acid. The number of life cycles of lithium-ion batteries, depending on the production technology, can reach from 2000 to 10,000 life cycles. Meanwhile, the number of life cycles of lead acid batteries is about 500-750, depending on the type of lead acid battery (deep cycle, AGM or GEL) [11; 12; 13; 14]. Lead acid batteries have certain advantages:low cost, easy maintenance, low fire hazard, etc. [15; 16; 17; 18]. Lead acid batteries are widely used in electrical energy storage systems, power surge smoothing systems, backup power supplies, etc. [19; 20; 21; 22; 23]. In various power support and backup power systems, lead acid batteries are easily replaceable with new ones. In this way, money is saved, and there is no need to buy all the equipment of the power support system [24; 25; 26]. In renewable energy systems, battery charging is uneven and chaotic. When using lead acid batteries, it is important to maintain the limits of the charging current mode of 0.1-0.3 C, because if these conditions are not met, the batteries wear out and degrade much faster. In renewable source systems, charging conditions are ensured in automatic mode using charging controllers, which are usually PWM or MPPT (maximum power point tracking) [27; 28; 29; 30]. When using batteries in systems of renewable energy sources, it is important to monitor the amount of charging cycles and the charging level. Based on these data, the battery life can be predicted [1; 3; 4]. There are many developed battery performance monitoring systems, but most of them usually only monitor the charge-discharge level in certain systems (such as energy storage systems, backup power systems, etc.) [5]. After an analysis of the literature, it became clear that most of the monitoring systems of the working parameters of the batteries are of a narrow purpose (e.g., for monitoring the battery charge level). Meanwhile, monitoring systems intended not only for determining the battery charge level but also for monitoring wear and tear, the number of charge-discharge cycles and systems with advanced capabilities, which are little studied. In other words, the battery parameter monitoring systems proposed in the literature lack universality.