This Master’s thesis is to construct a charge controller for safe charging a lithium-ion battery with overload protection by a solar cell panel with high charging current. A balancing unit has to equalize voltage for equal charge condition of the individual battery-cells which are connected in series to guarantee the equably charge of the battery. A further supervision is needed to detect voltage drop or surge. Voltage surge leads to defective cells and in particular can cause hazardous situations if the overstressed cell would catch fire (thermal runaway). Nearby cells also can catch fire and are able to endanger surroundings. Protection is also necassary to avoid the danger of a short circuit at the supply end. The different operation modes, the voltage of the battery and the charge current have to be displayed in an appropriate way. To guarantee reliability, the whole unit shall be constructed by using analog electronic elements like operational amplifiers, transistors etc. Microcontrollers would not be a good choice because of their error rate in software and hardware. Analog electronic elements are also cheaper in purchase and more reliable in operation. The previous attempt to purchase the single components like charge controller, balancer, display unit and protection unit, to fulfill the requirements was difficult respectively not possible. To find a complete system with the needed features was impossible. These reasons lead to the implementation of this Master’s thesis.