Battery Warning Light Always On When Car Runs Fine. What's Wrong?

[Spunky Munky]

Hi guys, recently my R33 GTR's battery warning light started flashing and now remains permanently on when the car runs fine and shows no signs of stalling or drained of power. What's going on and how to fix?

Firstly, I had the car at a motor mechanic for a couple of months where it was hardly driven each day so is the battery dead? This battery was brand new and only replaced 5 months ago. Ever since taking the car home, it's been on a trickle charger and only driven monthly but the charger does indicate that the battery has been fully charged so not sure why this is happening.

Recently, my amp/sub combos earth wire going from the "control" went loose so I had to fix and it sparked a few little sparks which is normal so not sure if this had anything to do with it. I assume not ?

Any help would be much appreciated.

[StevenCJR31]

usually that light means the alternator is on its way out but you say the car runs fine?! hmm odd

[DVS JEZ]

alternators have 2 circuits. one for charging and one for the warning light. sounds like the warning light circuit may be faulty. get a multimeter and check the charging voltage on the battery terminals to be sure the alternator is charging correctly

[kitto]

The warning light is a part of the excitation circuit through the regulator.

The regulator is most likely on the way out.

When that circuit fails the alternator stops producing charge as there is no excitation current to produce an electro-magnetic field inside the armature.

[500hp]

That's the alternator or

The regulator on its way out !

[Charles89]

I think a blown horn fuse can make the battery light come on too

[Spunky Munky]

Thanks everyone. I will check and will post up the results. Many thanks

[Spunky Munky]

Update: so the problem got worst. Slowly the battery just won't hold charge anymore and eventually I found myself stuck in the middle of the road with no power so it's at a friends house now.

You guys think the alternator is home or more the battery dead?

I'm leaning more toward the battery.

[DVS JEZ]

jump start it and test the charging voltage with a multimeter. if its charging(14 or so volts) then its the battery. if its not charging its alternator

[kitto]

Alternator for sure.

The tell tail signs are there.

The battery warning lamp was coming on notifying you that the alternator was starting to fail. Eventually it did completely fail and the entire car from that point on ran off the battery which then lead to a complete flat battery and your car stuck in the middle of a road.

Replace the alternator, stick the battery on charge for 24 hours and you should be good to go.

[Spunky Munky]

Thanks guys. Really appreciate it. I will get it looked at by a mechanic this weekend. Hopefully this will serve as a lesson for others.

Cheers

[Spunky Munky]

Ok everyone. My mechanic has confirmed it is the alternator.