Calibrating

[mr.prick]

What is the best way to calibrate the V2 inputs?
Specifically: how to filter out noise, what voltage precision, tool to do this.
Thanks

[joecar]

You mean calibrating the AD inputs... use 1 and 2 AA Duracells and a DMM (high impedance voltmeter).

My 2c.

[mr.prick]

This is what I have been doing but,
there they tend to be a slightly off.
My DMM is not the best brand and the V2 needs power
and ground from the car to be able to set them.

I may just need a new DMM that is more sensitive,
also I think there is a lot of ground noise from the car.

[joecar]

Car power source is noisy when engine is running, or if engine is off then any electric motor may introduce noise, but either way the battery should soak up noise...

What is the voltage between the ground point(s) and the battery negative...

And also compare these two:
* voltage between batt pos and neg,
* voltage between batt pos and ground point,