Voltage reading error

[Jim4Beam]

Hello,
first let my say thank you for the good and easy library!
I got messed up with the adafruit one.

I have a 0.001Ohm (1mOhm) Shunt at a 24V (nominal) batterie system. Max Voltage is 27V vully charged. Max Current is +30A and -120A.

I have set the defaults in the .h file to:

define D_I2C_ADDRESS 0x40 // I2C Adresse(64)

define D_RANGE 1 // 0: 0-16V, 1:0-32V

define D_GAIN 3 // Range: 2: +-160mV, 3: +-320mV

define D_SHUNT_ADC 3 // ADC 3: 12-bit, single sample, 532uS conversion time

define D_BUS_ADC 3 // -||-

define D_MODE 7 // 7: continuous conversion

define D_SHUNT 0.001 // R-Shung [Ohm]

define D_V_BUS_MAX 32 // U-Bus-Max [V]

define D_V_SHUNT_MAX 0.160 // U-Shunt_Max exp. [V]

define D_I_MAX_EXPECTED 150 // I-Max exp. [A]

Current works fine, BUT the voltage reading is at 26V (Multimeter) -6V!??
If i measure the Arduino Vcc its ok 4,8V.
If I set #define D_RANGE to 0, it reades 16,00V at max Battery Voltage.

What am I doing wrong, or have i grilled my INA219?

Thank you!

[Jim4Beam]

found and fixed the Problem. In INA219.cpp line 137:

// returns the bus voltage in volts
float INA219::busVoltage()
{
//int16_t temp;
unsigned int temp;
temp = read16(V_BUS_R);
temp >>= 3;
return (temp * 0.004);
}

Changed temp variable to unsigned int! Now the voltage reading goes up to 30V. :)

[johngineer]

Great! I'll update the code next chance I get. Thanks!