float readBatteryVoltage() {
int rawValue = analogRead(batteryPin) ;
// Convert rawValue to voltage (adjust these values based on your setup)
float voltage = rawValue * (4.2/ 1023);
return voltage;
}
int calculateBatteryPercentage(float voltage) {
// Determine your battery's voltage range and corresponding capacity
float minVoltage = 0.0; // Minimum voltage
float maxVoltage = 1023; // Maximum voltage
// Calculate battery percentage based on voltage range
int batteryPercentage = map(voltage, minVoltage, maxVoltage, 0, 100) ;
batteryPercentage = constrain(batteryPercentage, 0, 100); // Limit to 0-100
return batteryPercentage;
}
I need help in displaying battery percentage, this current coding helps to display them in percentile form(100,75,50,25, 0 ) instead of exact percentage reading, how can i modify them?
fyi it is a 12 V battery pack into a voltage divider and dropped to 4.2 V going into pin A2.
You are right, im sorry i didnt change the coding properly
float readBatteryVoltage() {
int rawValue = analogRead(batteryPin) ;
// Convert rawValue to voltage (adjust these values based on your setup)
float voltage = rawValue * (4.2/ 1023);
return voltage;
}
int calculateBatteryPercentage(float voltage) {
// Determine your battery's voltage range and corresponding capacity
float minVoltage = 10.8; // Minimum voltage
float maxVoltage = 12.6; // Maximum voltage
// Calculate battery percentage based on voltage range
int batteryPercentage = map(voltage, minVoltage, maxVoltage, 0, 100) ;
batteryPercentage = constrain(batteryPercentage, 0, 100); // Limit to 0-100
return batteryPercentage;
}
But the 2x16 LCD with I2C Module is still showing (100,75,50,25, 0). I have read some sources saying it might be the Arduino bit transfer limit, im not sure.
Thanks for the correction.
#include <LiquidCrystal_I2C.h>
LiquidCrystal_I2C lcd(0x27, 16, 2); // I2C address 0x27, 16 column and 2 rows
const int batteryPin = A2;
void setup() {
lcd.init(); // initialize the lcd
lcd.backlight();
lcd.clear();
}
void loop() {
float variableBattery = readBatteryVoltage(); // Implement your function to read voltage
int batteryPercentage = calculateBatteryPercentage(variableBattery);
lcd.print(" Batt=");
lcd.print(batteryPercentage);
lcd.print("%");
delay(1000); }
float readBatteryVoltage() {
int rawValue = analogRead(batteryPin) ;
// Convert rawValue to voltage (adjust these values based on your setup)
float voltage = rawValue * (4.2/ 1023);
return voltage;
}
int calculateBatteryPercentage(float voltage) {
// Determine your battery's voltage range and corresponding capacity
float minVoltage = 3.6; // Minimum voltage
float maxVoltage = 4.2; // Maximum voltage
// Calculate battery percentage based on voltage range
int batteryPercentage = map(voltage, minVoltage, maxVoltage, 0, 100) ;
batteryPercentage = constrain(batteryPercentage, 0, 100); // Limit to 0-100
return batteryPercentage;
}
This is the complete coding, thank you so much for your patience.
float readBatteryVoltage() {
int rawValue = analogRead(batteryPin) ;
// Convert rawValue to voltage (adjust these values based on your setup)
float voltage = rawValue * (4200.0/ 1024);
return voltage;
}
int calculateBatteryPercentage(float voltage) {
// Determine your battery's voltage range and corresponding capacity
float minVoltage = 10800; // Minimum voltage
float maxVoltage = 12600; // Maximum voltage
// Calculate battery percentage based on voltage range
int batteryPercentage = map(voltage, minVoltage, maxVoltage, 0, 100) ;
batteryPercentage = constrain(batteryPercentage, 0, 100); // Limit to 0-100
return batteryPercentage;
}
I think the problem is to do with the map() function using integer maths.
How is the Arduino powered ? If that is battery as well then simply using Vcc may not tell you much because the analog values are relative to Vcc unless you explicitly use the internal reference voltage. Search for "Arduino secret voltmeter" or similar.
Battery voltage won't tell you much about the actual battery capacity.
For a Li-ion battery the voltage will read 3.7V during 80% of the discharge time.
During he first 10% it will be above 3.7V and during the last 10% it will be below 3.7V.
So it's not surprising to only see numbers like 100, 75 50, 25.
Yes it is surprising since nothing in his code rounds the value to a factor of 25
If you had say that it's not suprising to see 100% during long time, then 120% (constraints to 100 with his code) and then 70% for eg for 10 last pourcent of its charge, then okay it's not surprising.
But pls have a better look to what he asked and you'll see that this is NOT normal
Nope I don't since in his code there is no part of it that rounds the value to a factor of 25 according to me... That's why it's not normal and actually even surprising
Correcting you from saying it is not surprising doesn't mean I have a solution. It's just to avoid people that don't know a lot about this stuff to think that something in that code makes the batteryPercentage variable's value rounded to a factor of 25
@willi12345 , that is exactly your problem. Try changing your function to the old-school linear interpolation:
int calculateBatteryPercentage(float voltage) {
// Determine your battery's voltage range and corresponding capacity
float minVoltage = 3.6; // Minimum voltage
float maxVoltage = 4.2; // Maximum voltage
return constrain(100 * (voltage - minVoltage) / (maxVoltage - minVoltage),0,100);
}
