I recently lot my meter for my LiPo. Now, I wish to read my 3s lipo's volts on my Nano
But how can I read all 3 cells simultaneously? Connect + to a0, a1, a2 then - to gnd?
Also, how accurate will it be?
Without complex wiring you should be able to read the voltage on cell A, on cells A + B together and on cells A + B + C together and then work out the voltage on cells B and C by subtraction.
You will need to implement voltage dividers to reduce the combined voltage of A + B and of A + B + C to values below 5v before connecting to the analog pins.
The accuracy depends on the max voltage that is supplied to an I/O pin. For example if the max is 4.2v then the highest analog reading will be 1023 / 5 * 4.2 = 859. If the lowest voltage is 3.5v (you should not discharge a LiPo too deeply) that will give a reading of 1023 / 5 * 3.5 = 716. That means you could detect about 140 steps between full and empty.
...R
How can I implement voltage dividers? Like setup resistors in the circuit?
Let me figure this out -- each volt in analogRead is 1023/5=204.6. So, to know the voltage, I use
204.6x=analogRead(LiPo pin) where x is the voltage. Dividing what analogRead() returns, I get volts, right?
And what do you mean "complex wiring?"
Unrelated question: I bought some LM1117 but I forgot that I had some 1s lipos sittong right in front of me! How would I wire that up? + to vcc of nRF, and - to gnd of nRF, or - to Arduino gnd?
JeromeAriola:
How can I implement voltage dividers? Like setup resistors in the circuit?
Look up "voltage divider" with Google
Let me figure this out -- each volt in analogRead is 1023/5=204.6. So, to know the voltage, I use
204.6x=analogRead(LiPo pin) where x is the voltage. Dividing what analogRead() returns, I get volts, right?
why make things so complicated? What is wrong with 5 * analogRead() value / 1023
And what do you mean "complex wiring?"
if you want to read the voltage on the two "higher" cells separately you will need a circuit that can isolate the negative pins from the overall circuit GND. Not easy to do. Of course I am assuming you want to measure the voltages without removing the cells.
Unrelated question: I bought some LM1117 but I forgot that I had some 1s lipos sittong right in front of me! How would I wire that up? + to vcc of nRF, and - to gnd of nRF, or - to Arduino gnd?
A fully charged 1S Lipo will exceed the max voltage permitted by an nRF24. I have used a diode between the LiPo and an Atmega 328 and nFR24 to drop the voltage by about 0.6v
...R