OpenGD77

Posted: **Sat Mar 27, 2021 2:33 pm**

Hi Roger, Daniel and other developers!
I have 2 GD-77s bought in the "double pack", so they should be from the same production batch with the same parts.
However, they differ in the battery voltage measurement, so alsio in the estimated battery percentage.
For example, just now, one of the batteries has 7.94V measured by a multimeter on its contacts.
On one of the radios, it displays as 7.9V and 83%. On the second one, there is 7.8V and 77%.
The other, freshly charged battery, shows 8.42V on the MM, 8.4 and 100% on the first radio and 8.3 and also 100% on the other one.
I'll post the values for a discharged battery, whether it will be also 0.1V difference, or more, or less

.
What do you think, would it be possible to introduce a calibration factor (similarly as for the temperature) to compensate the measurement error ?
With regards & 73,
Pavel OK1PT

Posted: **Sat Mar 27, 2021 9:21 pm**

ok1pt wrote: ↑
Sat Mar 27, 2021 2:33 pm
Hi Roger, Daniel and other developers!
I have 2 GD-77s bought in the "double pack", so they should be from the same production batch with the same parts.
However, they differ in the battery voltage measurement, so alsio in the estimated battery percentage.
For example, just now, one of the batteries has 7.94V measured by a multimeter on its contacts.
On one of the radios, it displays as 7.9V and 83%. On the second one, there is 7.8V and 77%.
The other, freshly charged battery, shows 8.42V on the MM, 8.4 and 100% on the first radio and 8.3 and also 100% on the other one.
I'll post the values for a discharged battery, whether it will be also 0.1V difference, or more, or less .
What do you think, would it be possible to introduce a calibration factor (similarly as for the temperature) to compensate the measurement error ?
With regards & 73,
Pavel OK1PT

This question has been answered before.

The radio displays the internal voltage available to the radio hardware.

Also the value is truncated to 1 decimal point.
Internally a voltage of 7.90000 will be displayed as 7.9 and a value of 7.89999 will be displayed as 7.8
Using rounding won't help in this situation, as rounding just moved the position of the transition from 0.0 to 0.5

Even assuming the value was wrong by 0.1V this will have no measurable difference to the function of the radio.

The display of % is only uses as its convenient for people to get a rough idea of the battery voltage, its not a measure of capacity of battery remaining.

I don't know of any piece of consumer electronics, including expensive mobile phones, which actually gives a true reading of battery percentage remaining.

OpenGD77

Voltage measurement calibration ?

Voltage measurement calibration ?

Re: Voltage measurement calibration ?