My Ecutek bluetooth dongle is showing a lower voltage reading on my phone compared to when I measure the battery voltage.

I measured ~13.3V at the battery, which seems to be the consensus for normal range for these cars.

My Ecutek has always been showing an average of 12.6V which is concerning, because that's almost an entire 1V that my car is not seeing action with.

Anybody else get lower voltage readings from their ecutek device?

 

I hope everything is fine and i'm just being picky

 

I would expect a higher reading at the battery than via obd. Not significantly higher but somewhat. There are lots of voltage drops by the time you get a reading at the obd/ecu. Half a volt does seem somewhat high. I'd try another dmm at the battery.

edit: Voltage drops, not voltage~!@#

 

@spoolin03 think about all of the electronics that are in-between you batter and OBDII.
Also, was your car turned off when you checked the voltage at the battery, but switched on (but the engine wasn't running) when you checked the voltage through the OBDII?????
Personally I wouldn't see this as an issue, but that's me.

 

The voltage readings on the EcuTek device are not accurate and don't need to be. The only reason they are there is to verify there is enough voltage to flash the ECU without any issues. (aka bricking)

How do I know?
I have an EcuTek tuned ECU on my bench, connected to a TCM (via CAN bus) and I have added an OBD port. My power supply delivers 12.32 volts measured on a calibrated DVM.
The EcuTek app reads 12.03 volts.

Since the main micro controller in the EcuTek device is a 3.3 volt device, it can't measure the 12+ volts directly. A voltage divider is used to "split" the voltage down to a lower voltage so that the on board "analog front end" (aka analog to digital converter) The voltage divider will drop the 12+ volts down by about 80% or multiply the battery voltage by 0.20

This means that a 14 volts at the battery will be measured as 14.0 x 0.2 = 2.80 volts at the micro controller's analog to digital converter (ADC)
and 13.9 volts would be 13.9 x 0.2 = 2.78 volts
Often the voltage divider resistors are not high precision and that can throw off accurate voltage readings.

The easiest and most accurate voltage readings are through OBD PID 0x42: Control Module Voltage.

 

When I first start the car, it reads a healthy 13.98V from ECUteK

After driving around for a bit, maybe 3-5 minutes later, I can see the voltage starting to drop down to 12.6V average

No idea why the voltage is normal at first, and then drops down like that. Also, if I shut off the car and start it back up, it reads 13.98V again and then drops down as I drive around

 

It was running when I measured the difference

 

Seems normal to me, based of my torque readings. my max is almost 14v then levels out between 12.3-12.4. I suspect this is normal operation of the IPDM sending a lower duty cycle to the alternator after it detects battery has charged then lowers the voltage to lower the load of the alternator.

 

That is normal operation.
Think about it... after pumping our 700+ amps to the starter for about 1/2 a second to start the car, (I have measured this!!)
wouldn't you want to charge the battery to be ready for the next start? The Nissan engineers do

 

On another note, I've always been curious about data of a loaded alternator vs efficiency and power.

Though minimal, I can feel somewhat differences in performance between these charging voltages.

It's only when you start paying attention to this data that you start noticing how intelligent Nissan/Infiniti is and if this data is followed, many times it will yield with better efficiency.
This gas increase has changed my driving patterns and so far I've gone from 19mpg to a fantastic 22.