Logging Battery Voltage w/ EIO

[jimmyb496]

I wan't to log the output voltage of my Fuel Pump Speed Controller.

Has anyone successfully setup a voltage divider circuit to reduce the 12v signal to 0-5v range?

Do I need to take into consideration any amperage draw from the EIO on the interface?

I found this post on LS1 tech
http://ls1tech.com/forums/pcm-diagno...resistors.html

which refered to this document from innovate. See Last Page.
http://www.innovatemotorsports.com/s...MA2_Manual.pdf

[jimmyb496]

Just an update if anyone was looking to do this.

I built the circuit as described in the Innovate manual.

I think it actually works.

Tested it on my car battery which read 12.18V. The Aux wire (output) read 3.63V. I looks like my circuit is dividing by 3.36, which will be fine. Should mean I can log 0 – 16.8v w/ my 0-5v signal range. It would be nice to test it on something lower voltage like 3-6v just to verify the division is linear. I think my son’s little electric 4 wheeler uses a 6V battery.

I’m guessing the variance comes from tolerance in the resistor. (110k was actually about 100k, and the 220k was actually about 185k). However, when a checked resistance after soldering the wires, the resistance wire end to wire end was much closer to the posted kOhm rating. Maybe they factor that in, or maybe it was coincidence.

I tied it all in to my fuel pump voltage controller and will log the results side by side w/ the fuel pressure output. Should be able to see plain as day if there is a voltage drop relating to fuel pressure drop.