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### Topic: Voltage divider for lipo (Read 1 time)previous topic - next topic

#### cmcta82

##### May 13, 2012, 08:28 am
Hi,

I went to read the voltage value of my 2s lipo 7.4V in my arduino, i thinking do this with one voltage divider but donĀ“t know if i use lower resistance like 1Kohm and 10Kohm or resistance with highter values.

I use the lipo to powering the arduino and an Esc from an RC car.

What do you think?

#### Grumpy_Mike

#1
##### May 13, 2012, 10:00 am
Use 10K, that is optimal for the arduino's analogue input.

#### cmcta82

#2
##### May 13, 2012, 08:47 pm
And for possible noise from the esc the best to do is to put one capacitor between analog input and Gnd?what is the diference between resistance like R1=10k and R2=1K with R1=27k and r2=2.7k with same ratio?

thanks,

#### Grumpy_Mike

#3
##### May 13, 2012, 11:11 pm
Quote
what is the diference between resistance like R1=10k and R2=1K with R1=27k and r2=2.7k with same ratio?

More current flows with the lower resistance.
This may or may not be important.
Generally the more you want to take out of the divider the lower the resistance values should be. As a rule of thumb the current down the divider should be 10 times what you want to take out.

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