Abstract:
In the advent of cases where many automotive product facing risks of catching fires due to
use of Lithium-ion battery packs. Lithium-ion battery packs are designed to provide much
energy within very compact sizes. They are susceptible to thermal runaways due to any
internal damage causes like short circuit. These damages trace back to user actions such as
improper charging or overheating. As a result, a product capable of monitoring the battery
parameters and warn you of overvoltage scenario is very much relevant.
Objectives:
1. Display Charging and Discharging Cycle parameters over LCD/ThingSpeak (using
ESP8266
Wi-Fi Module).
2. Ensure cell-pack protection.
3. Calculate the SoC and SoH of the Cell Pack.
Plan of Action for Each Objective:
1. Display Charging and Discharging Cycle parameters over LCD/ThingSpeak:
•
The INA266 will provide with voltage, current and power values. It will be
connected across the 3-cell source pack. These data are intended to be
displayed over ThingSpeak interface.
Reference:
1. Datasheet of INA266:
https://www.ti.com/lit/ds/symlink/ina226.pdf?ts=1711875421011&ref_ur
l=https%253A%252F%252Fwww.ti.com%252Fproduct%252FINA226
2. Using INA266 for Battery Monitoring:
https://how2electronics.com/iot-based-12v-battery-monitoring-system-
with-esp8266/
2. Ensure cell-pack protection.
Internal SOC management is done with the help of 3S 12V 10A 18650 Lithium
Battery Overcharge and Over-current Protection board module.
This module helps in ensuring that within a pack amongst the cell there are
no internal faults such as short-circuiting or uneven charge distribution.
1. Module Details:
Reference:
https://robu.in/wp-content/uploads/2017/09/DATASHEET_ROBU.IN_.pdf
Additionally, to protect from user behaviour faults like over-charging a relay
driven from conditions of input from INA266 is used.
3. Calculation of Battery Pack Parameters:
•
SoC calculation:
SoC: It is the real-time or actual capacity of the battery compared to its full
capacity.
Technique to Measure SoC:
➔ Coulomb Counting:
Coulomb counting gives a relative change in SoC and not an absolute SoC.
If you measure the current over a given time step you have a measure of
the number of Ah that have left or been received by the battery.
Reference:
1. https://youtu.be/rOwcxFErcvQ?si=6eiNJcCzQYwjIize
2. https://www.batterydesign.net/soc-estimation-by-coulomb-counting/
•
SoH calculation:
SoH of a battery describes the difference between a battery being studied
and a fresh battery and considers cell aging. It is defined as the ratio of the
maximum battery charge to its rated capacity.
The SoH is an indicator of the degradation in battery operation over the time
as number of charge-discharge cycle for the battery increases.
Reference:
1.https://www.youtube.com/watch?v=imjbyeS1caI
video: Battery Monitoring System
code:power meter
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