Anyone else notice voltage changing?
 

Hi all, Sorry if this has been asked before i tried searching but didn't see anything.

almost a week with the new car and since i'm leaving the Temp and voltage gauges displayed, (2017 brz limited) I started noticing voltage drop between about a line over 12v to over 14v. I notice that with lights on voltage is up, but during the day voltage might drop between those two points.
No CEL lights or anything, is this some sort of smart load/charging detection to avoid overcharging the battery?

I have never heard of anything like this and all the cars I have own remain at 14v while engine is running.

Thanks.

Perfectly normal. This is not your dad's constant-voltage charging circuit. Programming brings the battery back quickly after starting. Then minimum charge during cruise for maximum fuel efficiency.

Here:

Awesome, Thanks for the replies, That is pretty impressive. I believe that it takes a few HP to turn the alternator, I remember someone hooking up a 5HP lawnmower motor to an alternator and when powering it, it would bring engine to a stop.

The other thing that freaked me out was the blue coolant light at startup. I think i read manual front to back and don't remember mentioning this, it mentions red light...After checking level of coolant, i figured it must be a cold indicator...which I have also never seen. Live and learn! :D

Thanks Tcoat, Where is that image from? Which vehicles had the previous sensor? Which looks nicer BTW, than the gray fragile looking one :D

The image is from the sales notes on the upgrades for the 17s. Everything prior had the old one.

Ah, BTW if one interprets "current" as in "the present time" the image gets confusing to understand. Had to read it like three times then I realize they mean electrical current.

LOL


Currently considering current can't capture correct caption capacity.

@Tcoat I wonder if the new battery sensor is compatible with older 86's? Is it a nice improvement over the old system?

Nope. Need the programming to use it.

This ^
Not to mention it is a different alternator as well.

I can confirm the same voltage behavior in my 2018 BRZ - I was just researching that earlier today, in fact. Freaked me out a bit also when I suddenly noticed it happening after about a week of driving.

The low engine coolant temp light is mentioned on page 205 of the manual - lumped in with descriptions of all the rest of the dashboard lights.

It almost work like a hybrid car. Try this when you notice the voltage is low (close to 12V): let go of the throttle to slow down on compression, the voltage will go back to 14V, to make use of the inertia of the car to charge the battery, since you're not using gas anymore, then as soon as you step on the gas, the charging will drop to 12V. May not work with an automatic.

It's without a doubt programmed differently for an automatic most likely. This is probably handled by the BCM/BCU and then communicates back to the ECU as they do mention LIN/CanBus communication. Its more kinetic energy recovery on the crank versus the wheels. Hybrids also don't use the engine compression for recharge as the atkinson cycle motors probably would be better suited and more efficient to running and charging if the drivetrain battery packs.