Explorer Phat - Read Lipo Voltage


#1

Is it possible to read the voltage of a Lipo with the analog pins of the Explorer Phat?
I tried it, but the voltage flows into the raspberry pi.
If yes, how do I connect it to the explorer phat?

Thank you ;)


#2

I cloud be wrong but you would probably solder a wire from the top left 5v pin to one of the analog inputs whilst the explorer phat is on the same header as zero Lipo. I definitely could be wrong but that is all I could think of! Hope that helps!


#3

The voltage of the 5V pin are always stable. But the Voltage of the Lipo is different.
I know how to connect it to an arduino board and how to read the voltage, but I think the analog pins of the pHat work differently.


#4

I suppose you could splice the red power lead and measure it that way?


#5

What do you mean by “the voltage flows into the raspberry pi”? What voltage is your LiPo and how are you hooking it up for measurement?


#6

I dug up a sensible application circuit from the bottom of this thread: https://electronics.stackexchange.com/questions/39409/how-can-i-measure-battery-voltage-with-my-mcu

But it seems a little overkill. The impedance on the ADS1115 inputs is 10M Ohm, and they’re 5v tolerant, so as far as I understand it, it should be able to to measure the battery voltage with very little leakage current using simply a direct connection.


#7

By direct connection do you mean splice on to the red lipo power cable?


#8

Assuming my understanding that the very high impedance of the analog pins would minimise leakage current, then yes. This is pushing the boundaries of my fundamental electronics knowledge- of which I have precious little :D


#9

What is the LIPO plugged into? There must be an up converter in there some where to get you 5V? On my Powerboost 1000c there is a BAT terminal where I can measure the actual battery voltage. I would think that could be measured via the explorer analog input? It has •Four buffered 5V tolerant inputs (perfect for Arduino compatibility)