This would dictate the designer’s system design. Different systems may require different priorities from the aforementioned list. ![]() But a careful tradeoff must be made, keeping power, speed, accuracy, cost and form factor (space constraint) in mind. There are also sophisticated battery monitors and fuel gauges, which are specifically designed for this function. Monitoring the battery case temperature is also vital as it provides a lot of information about the loading conditions, ambient temperature, or the presence of a fault.Ī typical simple solution to monitor battery voltage and temperature can be an analog-to-digital converter (ADC) or comparator with window function. Likewise, when the battery output is higher than required, a flag can be asserted when the battery is completely charged and no longer requires further charging. When the battery output voltage is lower than required, this means it is discharged and requires charging. One of their vital functions is to monitor/ control the state of the battery supply. When an event occurs, these circuits flag the micro (usually in the form of interrupts) to perform the required duty. In order to prevent system power dissipation, the controller needs to remain, for extended periods, in a sleep state, looking for flags presented in the GPI pins.Įngineers are resorting to using low-power circuits to continually monitor the vital functions of the system. As the workhorse of the system, the controller is usually power-hungry, so it does not make sense to let the controller do all the work. Microcontrollers/microprocessors would be the “brains” managing the system reliably and performing the required functions. This article discusses how some simple, low-power monitoring circuits for small batteries overcome this challenge.įrom a system design point-of-view, the systems engineer must carefully budget the system power requirement. Efficiently monitoring the health and state-of-charge (SOC) of these batteries without significantly affecting their SOC can be a challenge. It is however strongly recommended to connect the monitor directly to the battery, in principle a connection to the cigarrette lighter would suffice but for reasons unknown at this time the voltage at that point is 0.2 volt lower than the voltage measured directly on the battery.Small button- or coin-cell batteries power many of the portable consumer electronics in use today. The diode 1N4007 was included to protect the circuit from a wrong polarity connection. When you are satisfied with the adjustment, feel free to exchange the 200K potentiometer with resistors again.(after measuring the resistance from the potensiometer, obviously). Now, re-adjust the 200K potentiometer until LED 1 lights up. Change temporarily the resistors at pin 4 with a 200 Kilo-ohm potentiometer and reconnect a voltage from 10 Volt to the input. For example, let’s say you wanted to change to 10 – 13 volt, you connect 13 volt to the input (+ and -) and adjust the 10K potentiometer until LED 10 lights up. You can also change the to monitoring voltage level. The LED brightness can be adjusted up- or down by choosing a different value for the 4K7 resistor connected at pin 6/7 ![]() If you wish to use the ‘BAR’ mode, then connect pin 9 to ground, but obviously with increased current consumption. The above circuit diagram is set for ‘DOT’ mode, meaning only one LED at a time will be lit. You can modify this circuit to your own needs by making small modifications. This circuit, with the components shown, uses less than 10mA. The green Led’s indicate that the battery capacity is more than 50%, the yellow LED’s indicate a capacity of 30% – 50% and the red LED’s less that 30%. Check that LED 1 lights up at approximately 11.89 volts.Īt 12.65 volt and higher the battery is fully charged, and at 11.89 is considered ’empty’. Lower the voltage and in sequence all other LED’s will light up. Connect an input voltage of 12.65 volt between the positive and negative poles and adjust the 10K trimmer potentiometer until LED 10 lights up. Final adjustsments are simple and easy and the only device required is a digital voltmeter for the important accuracy and reliability. This easy circuit makes it possible to monitor the charging process to a higher level.
0 Comments
Leave a Reply. |