The battery at rest shows 12.48v attached, but disconnected goes up slightly. That is after 3.00 hours since last used
Not sure on age of battery as was on the car when I purchased it 3 months ago.
Looks new ?

 

I'd have to do some research, but I wonder if the logic for the battery light also monitors the battery condition to some extent. The monitor might decide the battery is drawing too much charging current, or something like that. Pure conjecture on my part, but might be worth investigating.

At the very worst, you're looking at either a new alternator or battery, or possibly both. If you replace the alternator, make sure it has an OEM regulator. Most aftermarket alternators will charge just fine, but have the light on constantly.

 

I would not go removing fuses as they mostly do several things and you're asking for much grief. Batteries are cheap compared to such as an alternator. Do not get an inappropriate battery (or alternator) or you can expect your more pain.

 

Thank you. But as I don't know if the alternator is already an after market one, I have asked the question if the readings I am getting are normal, and the light is on for no reason.
That being the case I could buy a new battery and put in the boot waiting for the day ,(which may never come) when the alternator does fail.
looking at ho hard it can be to change the alternator, I would rather not be doing it.

 

If the alternator was aftermarket, the light would be on constantly. Since the light is off some of the time, the alternator is OEM.

The light is telling you a problem exists. The trick is determining exactly what. The voltage reading itself seems normal. However, I don't know exactly what other conditions will also indicate a fault. Whatever the fault is, it seems to come and go, but the car is furiously trying to get your attention to let you know something ain't right. I wouldn't ignore it.

 

any other ideas? don't want to change the alternator unless i have to?

 

Personally, given the chance to gamble with your money, I'd try a new battery first. The battery takes a lot of abuse in these cars. If the battery is of unknown age, it's worth a gamble. Check the battery cables, too, especially where the ground cable mounts to the body.

I just looked in my shop manual. For a battery light illuminated, the very first thing to do was run a battery capacity test. If bad, change, the battery. No details were given of the capacity test. I believe that involves checking for a minimum voltage under a specified load. For testing, you may find it easiest to take the battery to a store that sells new one. Ask them if they have a capacitance-type tester. That's the most accurate test of battery health, not just the charge. If they don't have a capacitance tester, consider looking for a place that does.

Even if a new battery doesn't fix the light, I won't feel bad, as it will eventually fail. The only question is when and where. After that, you're probably looking at a new alternator. Your call.

 

good call a new battery is only 90 euros from a trade wholesaler here in france. to will give it a try, after doing a health check on it.

 

I have the same problem

 

Welcome to the forum Reggie,

Please post an intro in the new members section when you can.

What problem do you have? What car do you have?

 

If you have a bad alternator, the best way to get the correct replacement is by removing the old one and getting the jaguar part number from it so you can get an exact replacement by the number....otherwise you will have to stare at the red battery light