Battery light

its a bulb mate, what exactly are you fretting over?

Have you ever driven a car? The battery light is only supposed to come on when there's a charging problem or when the ignition is on but the engine isn't running. What's bothering me is that the light is behaving strangely as per my OP and it's glowing even though my multimeter tells me the battery is being charged.

probably because a motor factors part was used which differes slightly from the original part... i dunno, but u said it urself, the battery is charging, so what are u worried about...

Ever heard of the boy who cried wolf? If my battery suddenly stops being charged I want to know about it. And it was fine until this weekend so I want to know what's changed?

Just bugger off and let knowledgeable people with decent replies provide some help and stop hijacking this thread.

who exactly is crying wolf?

and and btw, if ur battery suddenly stops being charged, u will know about it, very quickly..

The battery light is crying wolf by being on when the battery is charging!

is it reaching 14.5 volts then cutting off when you rev the engine ?

Not so, I drove the TI at least 30 miles with a conked-out alternator. Showed no adverse signs for at least 20 miles, then things started going wrong one by one - the ABS light came on, then the rev counter stopped working, followed by the speedo, followed by the airbag light coming on, followed by a misfire and death about 300 yards from the garage I was driving to to get it replaced.

Firslt, check the earths, including the earth strap for the engine. If that's not it, take it back - summat isn't right.

i see

THe best I managed was 2 days in an old Nissan Cherry 100A F2.

The alternator's faulty. Or rather the part of the regulator that simulates the warning light is.

Hes right. you have a faulty diode, in the alternator. There are 6 zenner diodes, that convert your ac to dc and one of ems buggered. Take it back before the ac component now in your alternators output buggers something expensive.

The warning light is actually part of the circuit that feeds the voltage to the external field coil, via a single diode. Its coming on due to AC getting the wrong way past the diode. Needs fixing fast.

Cheers Burgerman, FFS this alternator business is turning into a proper saga.

Not zener diodes, although there may be one or more within the actual regulator.

There are usually 6 diodes to provide full wave rectification of the three phase output.

It's unlikely.

Normally three, one for each phase. This separate DC output is fed to the regulator which then controls both the field windings (rotor) and the ignition warning light circuit.

Ac getting into head units etc is bad! They dont like it one bit! Bit like connecting things up wrong polarity continuously. Fuel computers and engine management systems com under the fragile cat.

No idea, but I'd be going back to "alternator and battery" supplier and saying "Look at this. Fix it."

When the alternator died on my TI, the bulb never came on - I knew nothing about it until the windscreen wipers began to slow right down.

When it died on my first 405, the Battery light came on at low revs, and went out at higher revs. This point slowly worked it's way up the rev range until it was always on.

When it died on my second 405, there were no symptoms whatsoever. I just couldn't start the car one morning. And so I checked the battery, and it was totally flat. So I got a jump start, and drove to the garage. And the battery was still totally flat !

Was it a recon alternator that was fitted? I've just gone through

3 alternators in 6 months with the same problem. The garage gave in and ended up buying me a genuine bosch replacement, as it was costing them more money having to keep taking them out and sending them back.

I guess you just can't get decent parts anymore.

-Mark