How can we predict the remaining capacity of lithium thionyl chloride battery? Is there any hardware or software algorithm to predict the battery capacity while battery is in system use?
As the voltage of Li/SOCl2 batteries during discharge is constant for most of the time (while rather variable over temperature), voltage supervision approaches do not work. Thus 'only' "coulomb counting" remains. See eg. http://www.channel-e.de/designcorner/artikel/article/ueberwachung-der-batterieladung-durch-nanopower-iot-stromversorgung.html (sorry, only available in German) for details and some considerations.
If you need higher accuracy, it has to be noted that battery capacity significantly depends on the discharge current. Thus you have to take your load current (profile) into account as the nominal capacity may be lower than what your application circuit is able to get.
Hope this helps to start...
Hello Viral,
As Dreher has stated above, monitoring the load current would be more helpful in knowing the remaining time for the battery.
Further to that what I suggest is you make a standard load (current) run for your battery and then adopt this into your embedded software to estimate the remaining time of the battery. Off-course, there will be a little difference in the standard measurement as against the Dynamic current of the actual system.
But this margin should be (hopefully) to a minimum level.
You can use a high resolution ampere sensor with RTC and measure the mount of current supplied by the battery. you can use arduino 328 to interface a RTC and Current sensor. Also the atmel328 can be interfaced using USB and I2C protocol. get the datasheet of the battery from the manufacturer and match the discharge curve against time. program the atmel328 to send out status of the battery.
I have used this approach to handle batteries upto 20amps and it works.
Let me know if u need more details.
Thank you Dreher,Prasanna and Bishwajit for valuable suggestions. Bishwajit can you please share the reliable and accurate battery current measurement circuit which you have used in your design?
I am going to measure it with differential amplifier. Please share your suggestions if there is any other good option to measure battery current.
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