Battery light on & get brighter as rev's rise?

[ednovasr2]

high guys not sure if the alternator has just packed up on the way into work car park or not.
I've checked the belt all seems fine and cables to battery seem secure, will have to wait till get home to test witha multi meter.

Does it sound like duff battery (only got new one few months ago) or is it more likely to be knackered alternator if so how much are new ones roughly?

Cheers Peeps and happy snow driving

http://www.imageno.com/thumbs/20101220/b936n1pvl335.jpg (http://www.imageno.com/b936n1pvl335pic.html)

[MattBrown]

If its getting brighter, it could be the battery is flat, (usually they charge streight up to light off voltage when running)

I would point at either the alternator, or the wiring on the back of the clocks, this causes problems with the charging circuit.

[MK999]

it'll be the alternator regulating circuit, lights get brighter because the voltage is allowed to rise, it's the black box on the back of the back of the alt, getting just that is difficult though, normally means a new alt.

edit: and a battery doesn't "charge straight up" when the car starts, the alt just starts supplying the 14.4 volts a car runs on and the battery charges on when the battery only supplies 12.5-13.

[JensonLEI]

I have this problem which still isn't sorted, starts up first time for months now, dodgy wiring I suspect

[ednovasr2]

hum so i could be wasting my money if i just replace the alternator then?

I'll check that it not covered in snow as well causing it to short a bit. but then it is the origanl on since 1987 so might be worth replacing it lol

[MattBrown]

it'll be the alternator regulating circuit, lights get brighter because the voltage is allowed to rise, it's the black box on the back of the back of the alt, getting just that is difficult though, normally means a new alt.

edit: and a battery doesn't "charge straight up" when the car starts, the alt just starts supplying the 14.4 volts a car runs on and the battery charges on when the battery only supplies 12.5-13.


You know what I meant.

They rise to a voltage higher than the 12v that puts the light on I should say!

My bad lol

[Riggy]

mine had a prob like that lst year , alt was putting out way to much voltage, fried my ecu ,

dont know what engine you have in yours , but if its injection keep an eye out

[ednovasr2]

I have a 1300 sport with poo pirburg carb thing on it as sold my twin 40's :(

no ecu to melt lol

I put a multi meter on her n read 10.91 volts with everything electrical on and 12.91v with nout on.

What should it be 14.4v?

I will have to order an alternator as can't find anyone with one in stock lol and with Xmas post will have to use another car :(

Another mate thought it could be a cell down in battery causing the fault and i have let it run dead a few times last month where not used it.

[MattBrown]

Is it 12.91v fully loaded at tickover?

As that's quite good tbf.

[MK999]

I have a 1300 sport with poo pirburg carb thing on it as sold my twin 40's :(

no ecu to melt lol

I put a multi meter on her n read 10.91 volts with everything electrical on and 12.91v with nout on.

What should it be 14.4v?

I will have to order an alternator as can't find anyone with one in stock lol and with Xmas post will have to use another car :(

Another mate thought it could be a cell down in battery causing the fault and i have let it run dead a few times last month where not used it.

If you rev it it will most likely shoot to 20v+

[C612DNM]

If it rises about 14.4v (+/-) a bit, then the regulator is FUBAR.

Modern alternators generally provide about 13.2v idle, but as soon as the revs lift about about 1000, the output will run to 14.2/14.4v which is a proper charging voltage.

Nova's are prone to losing the earth from the alternator to the block, when that goes, you don't get a light on, just no charging.

They also have a habit of losing the earth from the gearbox to the chassis too. When that goes, the loom tries to make up for the lack of proper earth, leading to overheating looms and smokey bonfires!

Old original Nova alternators provide about 13.6-13.8v at "average revs" and about 14.2-14.4v at higher revs (4000+) from memory. Their regulators weren't that brilliant at regulation.

Earths on old cars are often the cause of all sorts of electrical woes - like not starting, or not charging. Lights that go screwlally, and best of all, impossible to trace misfires!

Going back to the light, what you see there is a difference between alternator output and battery terminal voltage. If the Alternator output is lower than the battery voltage, the light will be on.

Mrs C612DNM's old poxy Zafira had an alternator fail, the light didn't come on with that. The power steering packed up, then the lights all dimmed, and it all stopped! Oddly enough, after turning it all off for a few minutes, it came back to life and worked again!! That was partly earth related too, perhaps the flakey earth contributed to the regulator failure?

[craig green]

As above, my guess is it's earth related.

Give the g/box to chassis leg earth a good yank & check it isnt about to snap. I had one that came apart in my hands. The car wouldnt turnover & some of the dashlights were on even when the car was locked (no keys in ign)

[Yorkie]

When you have been out some where and go back to your car after the engine has cooled down, if you feel the alternator and its warm that could mean its draining power from your battery, had that problem with my old car.

Not sure where you would get one, ebay prehaps other wise scrappys but its not often you get novas in them and when you do there quickly stripped

[ednovasr2]

Alternator was knackered chap who took it apart said parts of the inners were melted oooops. Reconed for £30 and all aorted now