1 2 3 4 5

Project Abstract

The aim of this project is to develop a low-cost product to indicate the state of charge of a lead accumulator. The density and the temperature of the lead acid is measured to get a accurate value for the state of charge. This measurement is made with a special sensor which can be mounted on a conventional lead acid battery. This sensor requires an input voltage of 5V DC and gives an output voltage depending on battery charge from 1 - 4 V. The output voltage varies in proportion to the state of charge. In addition to the acid density, the sensor measures the temperature of the electrolyte, this value has an output voltage of 0 - 5 V. This must be taken into account because the gravity of the lead acid changes with a different temperature and the same charge state. These signals are guided into a control unit. In this control unit is a microcontroller which converts the input signals into suitable signals for the display, it also stores the signals on an internal memory chip.
The program for the microprocessor includes these following functions:

a) Output of the charge state
b) Output of the temperature
c) Issue of Time
d) record the state of charge and temperature values

The recorded data is stored on an internal EEPROM. In addition, the CSI has an USB - port. It is possible to write the data stored on the EEPROM to an inserted USB-stick. Thereby the data on the EEPROM get deleted. The recorded data can be analyzed on a computer. This is important to determine how the condition of the batteries and the temperature changed after a certain time. The system will be powered by an external lead-acid battery. The user of the CSI shall have no further technical knowledge. Through this system, the status of the battery can be easily monitored and will be mainly used in stationary battery systems. Our project is unique in this form and not on the market and will be available for any type of stationary battery systems.