Wireless battery maintenance unit
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The problem presented in this thesis has been to design a charge and monitoring system for high-voltage high-capacity lithium batteries to be embedded in WesternGecos marine seismic configurations. The design of this system is important because the current lithium batteries have built-in embedded monitoring circuits from the manufacturer that are not durable enough for the intended application. They break down in the harsh offshore environment. By making their own external system WesternGeco will have control over the electronics, and can reliably monitor the battery. The system also has the extended functionality of logging battery parameters and presenting them on a PC through a wireless connection, whenever the system is within range. The work presented in this thesis has been both theoretical and practical. It has consisted of learning the theory of lithium batteries, especially high-voltage high-capacity lithium batteries, evaluating power efficiency, designing the system and making a small scale hardware model of it. The chosen design of the charge and monitoring system is based on microcontrollers which use interrupt based event handling to maximize power efficiency. Due to hardware problems a functioning small scale model of the system has not been completed. A power efficiency evaluation of CPLD versus microcontroller with respect to data logging, and theory about lithium batteries ranging from a basic introduction to how to charge and monitor high-voltage high-capacity lithium batteries has also been presented in this thesis. It is also possible to read about how the charge and monitoring system has been designed, a power budget for the full scale system, and the work on the small scale model. Concluding the thesis is a small discussion about recommended future work and improvements in order to make a functioning full scale system.