LS Focus battery light coming on.

[prydey]

Hi guys, late yesterday my wife got home from the local shops, with her focus sounding like a bus (whirring/humming sound) and the battery light on, on the dash. popped the bonnet, smelled sort of an electrical type smell but nothing major. noise seemed to be coming from alternator area but hard to pin point.

this morning, i went out and put the multi meter on the battery. over 12v and jumps to 13-14v when i started the car, so alternator appears to be charging.

the car also seems to have 'fixed' itself overnight. the noise is gone, and the battery light isn't illuminated.

any ideas as to a possible cause. unfortunately i didn't get the multimeter out last night when it was doing it, but i can't see the battery still being at those levels this morning if it the alternator hadn't been charging on the trip home from the shop (about 2km)

could it be a seized bearing or something, that freed itself up overnight?

thanks in advance for any help.

[prydey]

bit of an update. went to go out this morning, got to the end of the street (50m) and it started again. drove straight back in to carport, popped the bonnet, and tested the voltage on battery. its down just below 12v, but holding. the noise appears to be coming from the tensioner looking setup above the alternator, although its hard to pinpoint. i wonder if a siezed bearing would put enough strain on the system to drop the voltage. i'm guessing the battery light just comes on once the car registers a voltage lower than a certain number??

[mik]

i dont think the tensioner would effect the voltage unless its locking up now and again , in which case the belt would soon be kaput,
i have however seen old alternators with a lot of mileage on them make a bit of a racket as the brushes on some of them where getting short and would charge intermittently, and sometimes would also make some weird noises, ranging from sort of a rattly sound to a whirring noise, i think this was the last bit of the brushes cocking a bit sideways or bouncing up and down in the holder if that makes sense.
how many ks has the limo got up ?

[marg99]

if the alternator is charging you should see bout13.5-14 volts in the system The two most common causes are worn bushes ( anything after 120-150,000 KLM or less if you had greater use like driving lights and additional sound system) or blown diodes caused from a short circuit in the system

[prydey]

car has about 70000km. its just the shopping trolley.

RAA checked it out this morning and apparently alternator is on its way out according to him. i'm always a bit skeptical of those guys ability, but pretty good chance the diagnosis is correct.

rang repco. they had a new one in stock. only $730 odd!! needless to say, its still sitting on their shelf. thats ridiculous.

i've pulled the old one out, checked the numbers and found genuine ones on ebay for $399, or non genuine for less than $300. both come with warranties etc.

[mik]

What brand of alternator are they Pridey ?

[prydey]

Denso

[DZFord]

My alternator packed up shop and did exactly the same thing - loud whirring sound, slight electrical smell and battery light on.

[Franco Cozzo]

Go to a local auto electrician with the alternator, they're usually cheaper than retailers, reco cost should be 1 hour labour + parts (which would be new bearings, new regulator, machine slip rings on lathe + coat of paint)

[mik]

i would have thought denso would have lasted a bit longer, they usually have a decent name in the auto industry dont they ? 160 k`s from the alternator in my old au(mitsubishi brand i think ?), maybe they are not getting enough airflow in the engine bay ie overheating?

[prydey]

i got told by an auto electrician that they don't fix them, as they are computer controlled. not sure if legit or he just couldn't be bothered doing it.

ended up buying one off ebay for $399. genuine, new and 2yr warranty. almost half the price of repco's price.

should arrive tomorrow morning and then i can put humpty back together.

[Franco Cozzo]

Originally Posted by prydey

i got told by an auto electrician that they don't fix them, as they are computer controlled. not sure if legit or he just couldn't be bothered doing it.

ended up buying one off ebay for $399. genuine, new and 2yr warranty. almost half the price of repco's price.

should arrive tomorrow morning and then i can put humpty back together.

Probably just CBF because I know they can be recoed, ah well you ended up with a new one anyway