[Diy_efi] GDI Cont'd

[Bernd Felsche]

On Mon, Jan 13, 2003 at 12:47:57PM +0000, Mike wrote:
> At 12:31 PM 13/1/2003 +0800, you wrote:
> >On Mon, Jan 13, 2003 at 11:53:05AM +0000, Mike wrote:
> >> I thought the 'new' volt standard was going to be 44v or was it 42 ?

> >> I seem to recall BMW and merc agreeing to either 44 or 42...

> >SAE seem to think 42V - though in essence it's just 3 * 13.8V :-)
> >based on the nominal "12V" system currently in use.

> >Plenty of agreement from OEM's. They're not just lining up funky
> >flywheels, but precious pumps, chilling compressors and brazen
> >brakes, all dependent on 42V technology.

> So are we really talking 36 v from the battery, nominal ?

Ermmm... no. The present "12V" system is actually a 13.8V system
when operating nominally. If the battery only produces 12V, it's
pretty R.S.

> Or is there impetus for a large SMPS/charger to keep a
> stable real 42v from a 36v battery, would make some sense ~`:o

The 42V is the "raw" voltage. It's fed to the main power consumers
that can monitor the voltage if they care, and adjust their current
draw, if it matters. Power electronics and controllers are now fast
enough and cheap enough so that regulating the voltage output for a
constant output isn't critical. 

i.e. Consumers either regulate their voltage internally for a
constant voltage; or they adjust their behaviour according to
available voltage. (EFI has been doing that for quite a while,
already.)

Car audio, etc will still have the "12V" available; either from a
DC/DC convertor, or simply pulling the bottom third off the battery
stack.

-- 
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