Variable Voltage Alternator: Can it be configured to be OFF?

[RoverLander]

The question is: Is there a paramater somewhere in the D4 3L system (a 2016 model in my case) that allows the variable voltage alternator function to be switched on or off? On would vary the voltage depending engine load/battery condition. Off would make voltage be regulated to a steady 14.7v (approx) at all time regardless of engine load.

Background:
When I first purchased the car the voltage varied. I can see this as my Tyre Pressure Monitor has a voltage display.

Then after about 12 months the starter battery failed. LR replaced the battery under warranty. However when I got the car back it ran at a constant 14.7V. Ie Variable voltage alternator seemed to be off. The car ran like this for 5 years with no battery problems. I was happy with this as I think it kept the battery in good condition.

I then recently had a new battery installed by LR. When I picked it up the service guy mentioned that they had reset the system for the new battery (or words to that effect). Now the variable voltage is back with voltage ranging from 12.3 to 14.9 depending on engine load.

I'm going to go back to the dealer to ask them to disable the variable voltage function again. I wonder what they will say? Does anyone here know?

[shack]

Try turning the headlights on

[DiscoJeffster]

You can’t disable it. They would have told the system you have a new battery and it will now know it’s capacity.

I believe if you remove the voltage sensing wire off the back of the alternator it defaults to maximum, but probably also flags an error on the dash.

There is nothing wrong with the variable voltage system. It monitors the charge of the battery and current draw of the vehicle to suit.

[RoverLander]

Try turning the headlights on

I may have already turned the headlights on a couple of times in the last 6 years of driving the car??? It makes no difference.

[drivesafe]

There is nothing wrong with the variable voltage system. It monitors the charge of the battery and current draw of the vehicle to suit.

While new vehicles have modern cranking batteries, which are designed to last longer in STOP/START equipped vehicles, having a constant voltage of around 14v and higher, applied all the time, will dramatically extend the battery’s lifespan even further.

[scarry]

While new vehicles have modern cranking batteries, which are designed to last longer in STOP/START equipped vehicles, having a constant voltage of around 14v and higher, applied all the time, will dramatically extend the battery’s lifespan even further.

Off topic,there is a diode some use on Toyota vehicles to bring the voltage up to around 14V,or just over.
Will this affect the alternator,overheat it or shorten its life?
TIA

[drivesafe]

Off topic,there is a diode some use on Toyota vehicles to bring the voltage up to around 14V,or just over.
Will this affect the alternator,overheat it or shorten its life?
TIA

Hi and unfortunately the diode does not work with Land Rovers, but if it did, it would not effect the alternator’s lifespan but would increase the lifespan of ANY batteries being directly charged by that alternator.

EDIT, and the higher voltage would decrease the drive time needed to recharge the batteries. In other words, the batteries would recharge faster with a diode fitted.

[RoverLander]

Can anyone advise what circumstances could result in the scenario I descibed above. Ie Variable voltage and Fixed Voltage and then Variable Voltage. Each time when in to a dealer to change the battery.

Do dealers change charging profile if there is a known problem with a battery going flat prematurely in a car? If so how.

[Tombie]

No they don’t.

The BMS is intelligent to know if the batteries capacity is reducing and will profile accordingly.

Once reset with a new battery the vehicle knows to run the right profile.

[DiscoJeffster]

Can anyone advise what circumstances could result in the scenario I descibed above. Ie Variable voltage and Fixed Voltage and then Variable Voltage. Each time when in to a dealer to change the battery.

Do dealers change charging profile if there is a known problem with a battery going flat prematurely in a car? If so how.

I can only assume the previous time your battery was replaced, the BMS wasn’t reset so it treated your new battery as a dying battery
Maybe that’s why it behaved as you describe