Paolo992

Hi guys,
among other things we have a voltmeter in the default view of right instrument on the dash. This moves in a 12-15v range (15v when breaking).
What is not fully clear to me is what it does indicate. Does it show how much the battery is being charged by the alternator, or the state of charge of the battery.
I'm asking it because most of the time the value stays rather stable at around 12.5/13v, implying an indication of the state of charge of the battery, while when I break it goes up to 14-15v (when breaking energy is recovered), which would instead imply an indication of how much the battery is being charged.
I looked at the manual, but I didn't find a precise explanation.
Can you help me?
Many thanks.

Bluehighways

IMHO a Voltmeter without an Ammeter is primarily Eye Candy for the driver. Knowing the system Voltage without knowing the Amperage output of the Alternator, tells me little more than an idiot light would do.

CanAutM3

Indeed, a voltage in the12-13v indicates a healthy battery, voltage above that indicates the system is charging the battery.

I however don’t find electrical system voltage to be particularly useful information for track or everyday driving.

I’ve customized my display to show:

• Water Temperature
• Oil Temperature
• Oil Pressure
• Boost Pressure

Paolo992

I agree an I have the same customization on my display

rasetsu

This is the way.

zachr

This is the way.

jhenson29

This is the way.

Mike Murphy

That’s a good point. A fully charged battery and near-zero energy recovery might still show high voltage even with little amperage.

In the old days, some cars only have an ammeter with a plus or minus figure. A healthy system would always show just a hair over zero on the positive side (energy flowing into the battery). Turn off the engine and with any lights on or power draw, it would show negative (energy flowing out of the battery). As long as it was positive, it didn’t matter much what the voltage was. If the number was a big, positive number, it meant that the battery needed a good charge, so maybe you’d be inclined to drive the car around a bit longer.

An ammeter also is better to determine if the battery was bad. After you started your car, or if the battery was dead after a jump, positive current would quickly return to near-zero, indicating the battery wasn’t able to take much of a charge. In any case, a volt meter would simply quickly climb to 14.4V and just stay there.

txpackers

Why are you breaking your car? Most people don’t like a broken car.

chelspeed

Unless you have a hybrid two years ahead of everyone else then when you brake (not break) no energy is recovered because there's nothing there to recover it with. All braking energy gets lost as heat.

Not sure why voltage should go up above the normal charging voltage of around 13.5V while braking. To be honest while I'm braking the voltmeter is the last place I'm looking.

Jeffrey Behr

...oohh... that's someting THIS SA would write. 🤨

Jeffrey Behr

So what, pray tell, is 'regenerative braking'?

CanAutM3

That’s not the case. Most modern cars now have intelligent charging systems, that mostly charge the battery during coasting or braking.