Had the battery light come on today during a journey but It went out Before I got home and hasn’t come on again since.
On measuring the battery voltage With the engine running it reads about 13.65v ,rising to 13.75v at about 2000rpm with everything electrical Turned on.
So just wondering what should the Output voltage be, and also does anyone know at what voltage the battery light Is activated?

Voltage? It depends on the Temperature and what type of battery your Land Rover is programmed for

Accept = voltage when the alternator is trying to fast charge

Float = voltage when the alternator is trying to keep the battery full

I don't know what Voltage will anger the ECU

Click image to enlarge

This thread shows the output of my Alternator

When turning on


B. Measure the Voltage at the battery with the engine at Idle

B1. Turn on the seat heaters and check the voltage
B2. Turn on the rear defroster and check the voltage
B3. Turn on the headlights and check the voltage
B4. Turn on the defroster for the front windscreen and check the voltage




https://www.freel2.com/forum/topic34604-30.html

Thank you for the reply.
It’s just a standard lead acid battery, so looking at the table There is enough to keep the battery charged at the moment ,but short of the readings you were getting from your car.
I’ll keep an eye on it for the moment But it looks like a new alternator could be on the cards before winter.

Tim,

Check your voltage again in the morning

Preferably early when it still cool

If the temperature is in the 60s or lower then you should be above 14 Volts when you first start the engine

Let me know

Thanks

Paul

what about the tiny blue wire from alternator that rubs through,puts light on but still charges,havnt got time to find thread ,but someone will point you in the right direction im sure.

Sid,

That’s an excellent point

Here is a thread I found

https://www.freel2.com/forum/topic32004.ht...nator+blue

Thanks

Paul

The blue wire problem makes for some interesting reading, so is something to look into.
Also shows that voltage outputs can vary quite a bit, so not too worried about my readings now, but will Still do some more readings.
Thanks for the pointers.

Tested the voltage again today and got 14.3v so looks like the alternator is working as it should, which makes it look like the blue wire could be starting to fail.
Thank you for the help.

The engine ECU - which is driving the alternator - is regulating the voltage based on the temperature.
Probably those initial 13.7v were with an hot engine bay, and the later 14.3v were with an not so hot engine.

Spot on alex, higher readings were with a cold engine.
I thought, rather simplistically, that the alternator produced more or less a constant Output voltage but now realise that the car has much more control over it depending on conditions.