Lead-acid battery is one of the most widely used electrochemical cells. These batteries have been associated with supplying energy to start the car. Currently used for propulsion and the overall operation of hybrid electric vehicles. When operating lead-acid batteries are made inside cell the thermal happens. The thermal going generate heat caused by chemical reactions during charging and discharging of the electrochemical system, the heat generated by ohmic and polarization losses and heat mediated contact with the environment. In this diploma thesis shows the principle of lead-acid battery and thermal processes that take places in the accumulator during its operation.

This Master’s thesis deals with the issue of lead-acid batteries, which are used in hybrid electric vehicles. The lead-acid batteries works in mode PSoC. In this mode occurs to degradation mechanisms at negative electrodes. These degradation mechanisms reduce the battery life. The practical part of Master’s thesis describes the production and a compilation of experimental cells and experimental part examines the characteristics of lead-acid batteries with the pressure to the electrode system.

This thesis deals with pulse charging lead acid batteries. The theoretical part provides the basic electrochemical reactions that take place in the lead pack, then this section discusses important parameters of lead-acid battery, its structure and distribution of the various types depending on the application. The next section describes the theory of charging lead-acid battery. The practical part deals with constructing experimental cells, which are then tested. The subject of the experimental execution and optimization of pulse charging modes in order to find a suitable pulse mode, which reduces the duration of charging, while significantly shorten the life of lead-acid battery.

This master´s thesis applies to puls charging of lead-acid accumulator and arising oxygen cycle while charging. First part of the thesis is focused on potential dividing of lead-acid accumulators and their construction. I also focus on priciples of submerged electrodes accumulator, gel accumulator and AGM accumulator based on oxygen cycle. The next topic are thermal and degradation processes inside accumulators and their influence on capacity and lifespan. In theoretical part am I describing ways of charging and I also point out possitives and negatives. Practical part focuses on producing experimental cell and its form. Experimental cell is tested to different modes. I evaluate their influence on temperature inside the cell, intensity of oxygen cycle and capacity. I compare their influence on duration of charging cycle to another possible charging modes.

The purpose of this survey has been to test and analyse the behaviour of battery systems mixing parallel strings of lithium and lead acid. The underlying theory of why batteries of different chemistries behaves together was investigated in order to understand the resulting tests. Several tests were made with different products, loads and chargers in order to confirm this theory and to discover cases where the system works good and where it works bad. Based on this understanding a script was made in order to find a point of the least annual cost. Annual cost was then compared with systems of Lead acid only and Lithium only. The final goal for the script was so that a salesman can input known parameters for a backup site. Script is then adding a small Lithium battery in parallel with a fixed Lead acid battery and, increasing Lithium in size and estimating depth of discharge for Lithium and Lead acid at each step, until desired breakpoint. A point of minimum system cost together with Li size is then represented together with the recommended current limits. / Avsikten med detta exjobb har varit att testa och analysera beteendet av batteri-system där man blandar litium och bly parallellt. Den underliggande teorin om varför batterier av olika kemier beter sig på ett visst sätt tillsammans undersöktes för att få en förståelse för testresultaten. Ett flertal tester gjordes med olika batterier, laster och laddare för att verifiera teorin och för att upptäcka fall där systemet funkar bra och där det funkar dåligt. Baserat på denna förståelse gjordes ett script med avsikten att hitta en punkt med en lägsta årlig kostnad. Denna kostnad jämfördes sedan med system bestående av enbart bly samt enbart litium. Det slutgiltiga målet med scriptet var att en säljare ska kunna fylla i kända parametrar för en viss telekom-anläggning. Scriptet lägger sedan till ett litet Litium-batteri parallellt med ett konstant bly-batteri. För att sedan öka på Litium i storlek och uppskatta urladdningsdjupet för Litium och bly vid varje steg, tills dess att Li har samma storlek som bly. En punkt för minsta kostnaden presenteras sedan tillsammans med optimal storlek av Litium samt rekommenderade max-strömmar.

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In this paper, an algorithm for estimating lead-acid battery state of charge (SOC) is implemented. The algorithm, named “Improved Coulomb Counting Algorithm”, was developed within a master thesis project (M. M. Samolyk & J. Sobczak, “Development of an algorithm for estimating Lead-acid Battery State of Charge and State of Health”, M.S. thesis, Dept. Signal Processing, Blekinge Institute of Technology, Karlskrona, Sweden, 2013) with cooperation of a Swedish company – Micropower – Research and Development department.  Currently used method at Micropower is Coulomb Counting; implemented algorithm compares coulomb counting method with open circuit voltage method and uses current, terminal voltage and temperature measurements to finally produce improvement for the very same coulomb counting method and get a better estimation of SOC.  The algorithm was implemented on Micropower Access Battery Monitoring Unit (BMU) using C programming language, so that it can be tested in real time application of the regular battery operation. In the end specific gravity measurements were also presented to comparing the methods.

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