Re: Need PWM controller for current source to charge 48v lead acid.

On 2012-12-21, John Larkin <jlarkin@highlandtechnology.com> wrote:

> Car/bike alternators are designed to be sort of constant-current
> devices, because that helps to drive the load over a wide range of
> RPMs.

All altenators, even ideal altenators, have an inherent current limit, 
due to the field strength limit.  

> As speed goes up, the open-circuit voltage goes up, but the w*L
> impedance goes up too, so things sort of cancel. The reason the load
> dump voltage is so high in a car is because the open-circuit voltage
> of the alternator is maybe 60 volts, to charge a 12 volt battery.

they behave like lossy current transformers.

> Anyhow, maybe the best regulator is a PWM'd mosfet short. The 50 amp
> switcher regulator inductors are free, namely the internal inductance
> of the alternator.


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&#9858;&#9859; 100% natural

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linnix wrote:
> 
> But can it be removed with no tools?  If so, I would throw a fit as well.  It would be open invitation for car thieves and broken windows.


   No, it took a set of security tools to remove.  Earlier radios were
easier to remove.  pull off the knobs, remove two 3/8"/24 nuts and
you're done. It could be done in 30 seconds on some cars if you had a
hollow shaft Xcelite socket driver.



   Ford was the worst for car radios.  The idiots put the car radio on
the left side of the steering wheel at the same time they started using
TO-220 output transistors.  They ignored the warning not to fan out the
leads at the transistor case, and they failed in droves.  You had to
remove the steering column, then the entire dash to remove the radio. 
It took about eight hours, if you knew exactly what to do.  After the
first one, we insisted that the dealer pull the radio, and put up with
the owner nt having the car for at least two days.

On Thu, 20 Dec 2012 10:39:33 -0500, the renowned "Michael A. Terrell"
<mike.terrell@earthlink.net> wrote:

>
>krw@att.bizzz wrote:
>> 
>> Michael A. Terrell wrote:
>> >
>> >Sjouke Burry wrote:
>> >>
>> >> Why not regulate the generator to output the correct charge voltage?
>> >> No conversion losses, only slight modifications to the
>> >> generator control hardware.
>> >
>> >   Or a switching regulator, so the engine can run at its most efficient
>> >speed?
>> 
>> Gee, that's a GREAT idea.  Maybe you should tell the car manufacturers
>> about that.  ;-)
>
>
>   Do you think the UAW would let them do anything to improve a vehicle
>if they can't pad the production line with more of their people?
>For instance:  Back in the '70s Delco designed a car radio that could be
>installed from the front of the dash with no tools.  The UAW threw a
>hissy fit, because it would cost a few union jobs.
>
>
>   At one time there were variable rate automatic transmissions which
>did optimize the power curve but I haven't heard of one in decades.

Nissan has been using Jatco CVTs in some of their models: 

http://www.jatco.co.jp/ENGLISH/products/

I've driven a couple of them a fair bit, and they're pretty good.
There have been some issues reported with reliability, but I've not
seen it personally. 


Best regards, 
Spehro Pefhany
-- 
"it's the network..."                          "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com

Spehro Pefhany wrote:
> 
> On Thu, 20 Dec 2012 10:39:33 -0500, the renowned "Michael A. Terrell"
> <mike.terrell@earthlink.net> wrote:
> 
> >
> >krw@att.bizzz wrote:
> >>
> >> Michael A. Terrell wrote:
> >> >
> >> >Sjouke Burry wrote:
> >> >>
> >> >> Why not regulate the generator to output the correct charge voltage?
> >> >> No conversion losses, only slight modifications to the
> >> >> generator control hardware.
> >> >
> >> >   Or a switching regulator, so the engine can run at its most efficient
> >> >speed?
> >>
> >> Gee, that's a GREAT idea.  Maybe you should tell the car manufacturers
> >> about that.  ;-)
> >
> >
> >   Do you think the UAW would let them do anything to improve a vehicle
> >if they can't pad the production line with more of their people?
> >For instance:  Back in the '70s Delco designed a car radio that could be
> >installed from the front of the dash with no tools.  The UAW threw a
> >hissy fit, because it would cost a few union jobs.
> >
> >
> >   At one time there were variable rate automatic transmissions which
> >did optimize the power curve but I haven't heard of one in decades.
> 
> Nissan has been using Jatco CVTs in some of their models:
> 
> http://www.jatco.co.jp/ENGLISH/products/
> 
> I've driven a couple of them a fair bit, and they're pretty good.
> There have been some issues reported with reliability, but I've not
> seen it personally.


   I stopped following new cars about 30 years ago. I'm glad they are
still working on them.

On Thursday, December 20, 2012 5:39:33 PM UTC+2, Michael Terrell wrote:
> krw@att.bizzz wrote:
> 
> > 
> 
> > Michael A. Terrell wrote:
> 
> > >
> 
> > >Sjouke Burry wrote:
> > >   Or a switching regulator, so the engine can run at its most efficient
> 
> > >speed?
> 
> > Gee, that's a GREAT idea.  Maybe you should tell the car manufacturers
> 
> > about that.  ;-)
> 
>    At one time there were variable rate automatic transmissions which
> 
> did optimize the power curve but I haven't heard of one in decades.

Maybe not US manufacturers. But these are available with CVT.
HONDA JAZZ
Mercedes A & B class
Audi A4 - possibly other Audis