Pete, that's a diagram for the regulator in the alternator, bottom right hand side shows connections to a rotor.... if I know how you do that without brushes  Yesterday I couldn't spell Engineer... Today I are one!
Inventor of the 'Guide-o-Matic automatic wheel alignment tool'
Former long term L322 owner, Up/Down graded to a Classic Tractor!

Cheers, mind you it does say "due to omission of carbon brushes." Maybe they have made them out of something different

I found a place in the states that sells controllers for late model cars that run huge ICE it tells the alternator to put out it's maximum when needed and ignores requests from the car when trying to reduce the load to meet emission regs..

His reply was that the Bosch ones fitted by BMW are very cheaply produced and don't have any way of bypassing the control, he said they had had a look and didn't fully understand how it was doing what they stated it does as the claims are similar to the GM and Jap cars but it didn't have the same hardware....

It all seems to work by smoke and mirrors...

Still think the battery is the prime suspect though... in fact I'm off outside to disconnect it and see what it reads in the morning... Pete
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2014 L405 Autobiography SDV8 4.4 Loire Blue Ebony interior
2012 L322 Autobiography 5.0 Supercharged Ipanema Sand Sold
2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Sold
2002 L322 Vogue 4.4 V8 Epson Green (Fatty Offroader) Sold
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Would seem it does indeed have brushes:

Quote:

Alternator

The alternators used on the Td6 and V8 engines are different in construction, but their principles of operation are similar. The alternator used on the V8 engine is located in a water cooled housing.

The alternators comprise a stator, a rotor, a rectifier pack and a regulator. A single output terminal is connected by a heavy duty cable to the battery positive terminal, via the starter motor battery connection terminal. The alternator isconnected to earth via its mountings.

The rotor comprises a field winding, wound around an iron core and mounted on a shaft. The iron core has extensions at each end which form North and South poles as current flows through the field winding. The rotor is located inside the stator and is mounted on bearings for smooth running and to support the rotor due to the high side loading applied by the drive belt tension.

The stator has three sets of coils made from copper wire. The three coil windings are connected in a 'star' connection, where one end of the winding is connected to the other two windings. The output current is supplied from the opposite end of each winding. Rotation of the rotor causes ac current to be produced in the coils.
The rectifier converts the ac current produced in the stator coils into dc (rectified) current required by the vehicle
electrical system. The rectifier comprises semi-conductor diodes mounted on a heatsink to dissipate heat. An equal number of the diodes are on the negative and positive side, with the remaining diodes staying neutral.

The rectifier also prevents current flow from the battery to the alternator when the output voltage is less than the battery voltage.

The integrated regulator controls the output voltage from the alternator to prevent the battery from being overcharged and to prevent the vehicle electrical systems from excessive voltage. The regulator, which is temperature related to optimise battery charging, sets the maximum output voltage to a nominal 14.5V and varies the output voltage depending on the state of charge of the battery and the loads required by the vehicle electrical systems.

The regulator has transistors which rapidly switch on and off to regulate the voltage output according to the voltage sensed internally. The regulator also provides a signal output to the ECM which uses the signal to adjust the idle speed under varying electrical loads.

Initially, the ignition switch supply provides an excitation current to the rotor at low alternator speeds via brushes which contact slip rings at the end of the rotor shaft. As the alternator speed increases the alternator becomes self exciting.

 Visiting from DISCO3.CO.UK
Discovery 3 TDV6 Auto HSE Zambezi Silver

^^ That's what I've been saying.

I do know that an old street racer's trick is to cut the power to the Ing. lead so that the alternator is just spinning and not nicking any HP's for the battery, during maximum power applications. In other words they turn off the alternator to get more power. And to do this you need to remove the power that supplies the rotor's magnetic field... cut the white, or was it red, or was it

While the alternator uses a rotating magnet in a large winding of copper wire to produce electricity, it does not actually have any magnets in it, except the one wire american ones and we wont go there It uses another copper winding in the middle of the rotor to produce the magnetism, hence the need for brushes to transfer the power to the spinny bit to make power! Yesterday I couldn't spell Engineer... Today I are one!
Inventor of the 'Guide-o-Matic automatic wheel alignment tool'
Former long term L322 owner, Up/Down graded to a Classic Tractor!

I have had quite a lot of experience working with lead acid batteries of different size etc.
The recognised best method of testing either individual cells or full batteries was :-
1) disconnect from load.
2) Fully charge.
3) Leave to stand for minimum of 3hours.
4) Plot graph of test discharge, voltage / time. (using a suitable load ) eg. for a 12V car battery a 12v sealed beam headlight clipped across is perfect.

A smooth line discharge shows a good battery/cell.
A faulty battery will show up by stepped voltage drops.

Hope this is helpful.

miggit wrote:

It uses another copper winding in the middle of the rotor to produce the magnetism, hence the need for brushes to transfer the power to the spinny bit to make power!

Indeed - unless you double up the system to make the brushless variety.  Visiting from DISCO3.CO.UK
Discovery 3 TDV6 Auto HSE Zambezi Silver

Haylands wrote:

Went laning yesterday, had the battery on charge over night... engine off voltage read 13.2 after being charged all night... drove for an hour at 70mph and it read 14.2 or 14.2 the whole way....

Got there and switched off, voltage read 12.4

Drove around all day and voltage varied between low 13 and 14, got home after long day (that's another story) after another 1 1/2 hours on motorway at 14.1 and 14.2... Battery at lunchtime today read 12.4...

I recon the battery is failing.... ???

Another set of data similar to yours....

This morning Battery was placed on charge while connected to car (small 5 amp charger - nothing fancy - recognises full charge then trickles) for around 4 hours.

Went for a short drive (10 minutes) - car showed 14.1-14.3V all the way.

Stopped(not noted voltage) - then drove back - Voltage 13.3 to 13.9 all the way. Dropped to 13.3-13.6 with lights on, fan on about 5, and rear de-mister on. Stopped - battery about 12.3V

My own thought was possibly alternator varying output so it does not fry the battery

Anyway just food for thought - our cars are probably equally as ? Howard
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2002 4.4 V8 LPG Tartarini
Have RSW AllComms in Cheshire J17 M6 - happy to help.
*Gone: Classic Vogue SE Auto V8 3.9

Well I think I may have found the problem....

A few weeks ago the headlight wiper on the passenger side gave up and the wiper was sticking straight up... to make it look better I unbolted it and moved the arm down to where it should be at rest.... I did notice the other day it had gone down past it's park position and was resting on top of the bumper...

When I disconnected the battery I measured the voltage and it was 12.41, then 12.42, then 12.43... so it appears it did have a draw on it (Ign been off for a few hours) I reconnected it and heard a thud coming from the headlight, remembered the wiper arm so unhooked the battery and reconnected again and sure enough the wiper arm thudded into the bumper... seems the wiper is trying to park and I stopped it by moving the arm, it's got a permanent feed so it parks if you switch off with it running... Seems the motor has been sat there trying to park for a week or so... poor little thing....

So it seems it was all my fault....

I'll have a play tomorrow and try to confirm my theory...

Anyone got a spare passenger side headlight wiper motor??? Pete
__________________________________________________
2014 L405 Autobiography SDV8 4.4 Loire Blue Ebony interior
2012 L322 Autobiography 5.0 Supercharged Ipanema Sand Sold
2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Sold
2002 L322 Vogue 4.4 V8 Epson Green (Fatty Offroader) Sold
-Click for Project Fatty off roader-

Yes! Yesterday I couldn't spell Engineer... Today I are one!
Inventor of the 'Guide-o-Matic automatic wheel alignment tool'
Former long term L322 owner, Up/Down graded to a Classic Tractor!

Is that "yes" it's my fault or "yes" you have spares...???

And don't say "yes"....  Pete
__________________________________________________
2014 L405 Autobiography SDV8 4.4 Loire Blue Ebony interior
2012 L322 Autobiography 5.0 Supercharged Ipanema Sand Sold
2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Sold
2002 L322 Vogue 4.4 V8 Epson Green (Fatty Offroader) Sold
-Click for Project Fatty off roader-

Yes, and Yes, I have 2 motors

I believe that the passenger side is 0 309 206 221 Yesterday I couldn't spell Engineer... Today I are one!
Inventor of the 'Guide-o-Matic automatic wheel alignment tool'
Former long term L322 owner, Up/Down graded to a Classic Tractor!

I have just a senior moment... smurfing around trying to confirm that the part number is the nearside........... didn't notice the bloody great L on the unit and the other has an R  Yesterday I couldn't spell Engineer... Today I are one!
Inventor of the 'Guide-o-Matic automatic wheel alignment tool'
Former long term L322 owner, Up/Down graded to a Classic Tractor!