Bf Alternator

[kawerx]

I know on the bf's the alternators switch on and off as required by battery voltage.this is to help reduce emmisions by creating less drag on the motor.

My question is how boes this effect performace of the electrical systems?

Because an alternator charges at 13.8volts

A battery runs around 12volts.

Now if the alternator switches off (like the bf's does) wouldn't this leave you with just 12volts.

would this be enough to effect performance of things like headlights,stereos,ignition systems,fuel pumps ect?

[Paradoxx]

I didnt know that... sounds a bit strange IMO

Most systems in the car run at 14.4v which is the normal charging rate of the alternator. I dont see how it would save any emissions by cutting it off. There isnt much drag on the engine unless the car is sucking power to run lights, fans etc... in which case I would say it would be in the ON state

[Ralph Wiggum]

Any alternator only provides the current to run the load thats applied to it. im not sure how you would turn off an alternator? i spose you could turn the field coils off or something like that but then you'd need to excite it to get it charging again. I guess they could switch the load to the battery but then the alternator would need to supply more current to the battery to maintain the charge rate........goes round in a big cycle really...the power to run the cars electrical system has to come from somewhere and thats the fuel tank....in a roundabout sort of way.... .....

[kawerx]

I think it has a clutch set up like an air-con compressor and only comes on as required.

Can someone with a BF run out and look at the front of you altenator and see if it has a clutch on the puuley?

if it does a photo would be nice.

if I'm wrong I'll get back in box.

[ZAP]

I think you are wrong, my alternator looks like my BA one.

I do not see much point in having the alternator disengage as there is always a power draw from the ignition/fuel/pump/accessories.

[kawerx]

I think I misunderstood it a bit.

found this: ford

[cqae]

not sure about the BF alternators, but the BA & rpevious have all been the same. The all have internal regulators, but achieve results differently depending on manufacturer. The can have Bosch, MItsubishi or motocraft. But the all work on simialr theory. The regulator has a supply wire attached directly to the battery which is different to the charging output wire. It uses this to sense load & rgulates the field current accordingly. the longer field's duty cycle is on the more it will charge. this is regulated to maintain around 14.5v under all loads. Some vehicle have one way clutch connected to the drive pulley which is to smooth out rotation & lessen loads in certain situations where the engine potentially spins slower than the alternator. I have never seen one on a falcon, usually only on mercs,opels & other euro crap. as far as switching off for efficiency, the alternator will charge less when required by lessening field current when conditions allow, which in turn lessens engine load from an alternator & saves fuel & emmissions, cos I dont know if anyone has tried, but when an alternator fires up & tries to charge they are bloody hard to turn

[mls]

Hmmm, I read it as the alternator has a higher output capacity which means they can slow it down a little to give the required output necessary, which means less inertia carried by the alternator.

They'd do this by either increasing the alternator pulley diameter, decreasing the crank pulley diameter or both.

Just my thoughts on it.

[Jim]

This article pretty much explains the hows and whys of the smart charge alternator on the BF.

http://www.automotivedesignline.com/howto/...icleID=53701389

Page 2 gives the benefits.

I hope this explains things.

[Paradoxx]

"We also worked hard on improving the articulation index, or the ability to easily converse with passengers, and achieved an overall nine per cent improvement in this area," Hosking said.

How do they determine a 9% improvement on ability to converse with passengers :sleepystuff: