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Reading a signal to feed ADC with isolation

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adwnis123

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Hello, I have a Lead Acid battery 6V and I want to meter its voltage using Arduino's ADC. I want to do this with some kind of isolation between the battery and the ADC. Can this happen? What component/circuit should I use to build this?
 

Hi,

Can this happen?
Click to expand...
Yes, but relatively difficult.

Why do you need isolation? What isolation voltage?

A somehow good solution may be more effort and higher cost than the arduino itself.
What voltage range (of interest), signal frequency, precision, resolution? What sample rate?

Klaus
 

KlausST said:
Hi,


Yes, but relatively difficult.

Why do you need isolation? What isolation voltage?

A somehow good solution may be more effort and higher cost than the arduino itself.
What voltage range (of interest), signal frequency, precision, resolution? What sample rate?

Klaus
Click to expand...


I have a circuit with Arduino, sensors and a battery (6Volt) and I want to meter the battery's voltage using one of Arduino's ADC. But I do not thing it is a good idea to use directly connection of the battery to the ADC (even with a voltage divider), because maybe I face some short-circuits, I do not know for sure...! That's why I thought of using an isolator. As far as the resolution is concerned, Arduino provides 1024 bits, and the frequency: 1Hz is ok, and even lower...
 

Hi,

you worry about short circuits... and why do you think you can´t create a short circuit with some isolation?
I think the more devices you use the higher is the chance for a mistake.

I think the voltage divider solution (you need in most isolated case, too) is a very simple and rugged solution.
Choose the resistor values that the current isl imited to a safe value.
It´s used million times in many devices.

How is your arduino powered? From the same battery? --> Then isolation definitely makes no sense.

BTW: There are many, many discussions and descriptions about battery voltage measurement.
Do a forum search and/or an internet search.

Klaus
 
I use a DC-DC-step-down-converter and the 6.0-6.4 Volt I get from the battery, I convert it to 5 Volt, so I supply the Arduino from the USB jack
 

Hi,

does your DCDC converter provide true input-output-isolation?

If I understood correctly, then the power supply is:
Battery --> DCDC converter --> cable --> Arduino(USB_Jack) --> microcontroller


Klaus
 
KlausST said:
Hi,

does your DCDC converter provide true input-output-isolation?

If I understood correctly, then the power supply is:
Battery --> DCDC converter --> cable --> Arduino(USB_Jack) --> microcontroller


Klaus
Click to expand...

I use this type of converter:

https://www.pololu.com/product/2119

I don't know this information.

Yes the circuit connection you describe is what I use.
 

That DC to DC converter is not isolated. You can tell because it has only 3 pins. The ground pin is common to both input and output.

Bob
 
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