Hello, all.
I am doing a project in which I need to measure DC voltage up to 40V. I know that I could do a simple voltmeter using 2 resistors and a capacitor. However, I was looking to buy one module that could measure the voltage of this circuit since I am not experienced in this field. Do you know any type of product that can measure dc voltages up to 40 V. I have found the ZMPT101B but that is suited for AC. Or do you advise me to build a divider?
Thanks.
You want to reduce 40V to what?
I just wanted a sensor that I could buy capable of measuring up to 40 V. If I have to do a divider I would look into doing one capable of reducing 40 v to 3.3 or 5v depending on the resistors my laboratory has
It is very easy to build a resistive divider, but you need to specify the input voltage range of the device that will actually measure the voltage.
Here's a couple of links that might help.
https://ohmslawcalculator.com/voltage-divider-calculator
https://eepower.com/resistor-guide/resistor-standards-and-codes/resistor-values/#
For 40 / 5V, I would suggest R1 = 47k, R2 = 6.2k, 40V in / 4.66V out.
For 40 / 3.3V, R1 = 47k, R2 = 3.9k, 40V in / 3.06V out.
A 100nF ceramic capacitor from analog input pin to GND as well as double reading the analog pin will help with noise suppression.
Thank you. @jremington I knew that building a divider isn't that hard but I was looking if there was in the market a sensor capable of dealing with a 40 v DC, but i guess no so I will have to build a divider myself, I guess.
@JCA34F , the current of circuit won't damage the Arduino? I say this because the circuit may have current up to maybe 40 A, since the ESC controlling the motor (the goal is to measure the power given by the battery, that's why I need a way to measure the voltage since I already have a sensor for current measuring) has a limit of 40 A.
You can buy two of these and put them in series.
40V in will give you 4V out
oh, thanks and everything would be in series? output pins and also the input part (circuit part)?
thank you!
sorry for a (maybe dumb) question but the current value won't damage the sensors right?
The sensors in series will only draw about 530uA (0.00053A) when the voltage = 40V.
So your 40V DC supply need to be able to supply that much current to the sensor.
What is the current rating of the 40V supply?
What is your measuring device? What resolution do you need. How much time is allowed to sample the voltage? What other restrictions are there? Can you can simply use a volt meter.
I still don't know since that part of the project is being developed by another person who doesn't have an answer for that yet. but I know that the ESC, that will control the motor (from which I want to take values of electric power), is rated to up to 40 A.
I need to store and use the data for analysis later so I don't think I can.
Time is not really a problem since I will read data for a minute in a static condition, so it's not like a changing environment.
What do you mean by measuring device? I use an Arduino Nano.
Then no problem
Recording volt meters are available from such companies as Keithley, HP, Tektronix etc. This type if instrumentation is used for automatic testing,screening, etc. Here is a link to a Fluke. Fluke 289 True-RMS Industrial Data Logging Multimeter | Fluke use the term "recording volt meter" and you will fine a lot of choices.
According to this datasheet, the module has R1 of 30kohm and R2 of 7.5kohm. So if I use 2 sensors in series I would basically have 3 resistors in series (R1=30kohm, R2=7.5kohm and R3=30kohm) which added up would be equivalent to a 67.5kOhm resistor and then the divider with R4=7.5kOhm after right? Or am I thinking wrong? I am not really from eletronics area so sorry if I am being dumb or bordering
Nano has become a generic name for the form factor, which specific Nano are you using. Some are 5V others are 3V3?
You have a total of 4 resistors in series, 2x7.5K and 2x30K gives 75K.
The output is across the 7.5K resistor that is connect to ground.
So the voltage divider ratio is 7.5K/75K =0.1
