12V Battery Fluctuations

Hi srivenkat,

There will always be some voltage differences depending on where you take the measurements. The farther away from the Aux. Battery, the more the voltage drop due to loading. You can use your digital multimeter and verify it yourself.

Vincent

 

I did some testing this evening. The voltage at the jump point is identical to the voltage I saw at the cable that plugs into SGII; I used a Digital Multimeter and tested the voltage using the 2 extreme ends of the RJ-45 cable end. What this tells me is that the SGII itself is the one showing the lower voltage (~ 0.23v) than it is receiving. Perhaps there's a diode of sort within SGII that does some forward limiting while not allowing current to go from SGII to the OBDII port?

I suspect in the testing you did with the 9V battery, the SGII was showing you about 0.23v less than what the 9V was actually supplying...

 

More likely just a simple gain (linearity) error. A 0.23 volt difference is less than 2%.