measure percentage

[hahaxuan]

Hello everyone! I'm doing on our project on labview. We are using a battery and need to measure the percentage of power that the battery left. As the power used, the voltage will also decrease. Here is a table of the relationship between voltage and percentage. Can anyone help me to get the vary value of percentage? Thanks!

[altenbach]

Are you having a problem with LabVIEW problem or a problem with math? What have you tried so far?

[hahaxuan]

Both the problems...How to get the formula of the table? Then how to program on labview?

[P@Anand]

So what you mean here is, you want to display the exact percentage of battery depending on the voltage (Suppost 11.23 V mean 54% like that)? You can do a Linear fit (LinearFit.vi) with the Voltage as Y values and Percentage as X values (Or may be the other way) and find the Slope and Intercept. Then with the voltage reading Mulitply the slope and Add the intercept, you are done.

[altenbach]

Create an array of points (cluster of xy pairs, x=voltage, y=%), then use interpolate array with the given voltage.

[hahaxuan]

Actually it is not a linear one...

[hahaxuan]

Maybe a curve.

[GerdW]

Hi xuan,

either use Altenbach's suggestion (with linear interpolation between your data points) or calculate a polynomial regression of your choice. Then use PolynomialEvaluation function to calc battery state from voltage…

[crossrulz]

Using a lookup table as Altenbach suggested is the easiest way to go.

[hahaxuan]

I'm sorry...Can u give me a more detailed solution?