[DeTomaso] Alternator Options

doug351c doug351c at gmail.com
Sun Nov 28 01:29:01 EST 2010


Mike,

After reading more closely, my comments should have obviously been directed
at J. Sean Kean instead of you but they're applicable to everyone
considering a higher amp alternator.  I'm running an MSD-6AL, halogen
headlamps, three fans and an electric pre-luber with a 55A alternator and
have never had a problem with a sagging battery, even after long night runs
using halogen high beams.  I know of other Pantera owners who've installed
100A alternators and burned up their wiring harnesses.  Excess alternator
capacity is not necessarily a good thing.

As long as your ammeter shows a positive reading, your alternator is keeping
up with the load and this is an average thing so at idle it's OK to read a
negative as long as it reads positive with a few additional revs.

Doug

-----Original Message-----
From: doug351c [mailto:doug351c at gmail.com]
Sent: Saturday, November 27, 2010 10:11 PM
To: MikeLDrew at aol.com
Subject: RE: [DeTomaso] Alternator Options


Mike,

What all are you running in the way of electrical loads?

My guess is an MSD (7 amps or so) and aftermarket fans that probably draw
about the same amount of current as the stock fans because they're more
efficient.  Even if you're running a car stereo, the average power drawn is
likely only about 40W which is only and additional 10 average Amps after
factoring in class A/B amplifier efficiency.  (how loud do you listen?)

I recommend you judge your need for more alternator amps by measuring your
battery voltage after a couple hour run at night with everything on.
Measure the battery volts before and after the run and if they're close
(within 0.020V) , f'get about-it!

You may cause more harm with a 100A alternator than you think.  The stock
wiring and connections are marginal at 60A let alone 100A so please check to
see if you need to upgrade before you do so.

Doug Braun
blue 73L #5505

-----Original Message-----
From: detomaso-bounces at realbig.com
[mailto:detomaso-bounces at realbig.com]On Behalf Of MikeLDrew at aol.com
Sent: Saturday, November 27, 2010 8:33 PM
To: jskeane6 at gmail.com; detomaso at realbig.com
Subject: Re: [DeTomaso] Alternator Options



In a message dated 11/27/10 20 12 11, jskeane6 at gmail.com writes:


> I just replaced my voltage regulator, and it got me thinking about the
> alternator.  Is the stock 65-amp unit capable of dealing with the
> demands of the electric fans? 
>
>>>Fans, yes.   Fans, headlights, A/C fan, interior fan, and stereo?   No.


> > I don't know how many amps the fans draw,
> but I suspect it could be a fair bit. 
>
>>>And with more powerful aftermarket fans, all bets are off.


> > I went looking at the vendors'
> various web sites, but found surprisingly little in the way of
> alternators. 
>
>>>They all carry them, but it doesn't make much sense to buy an alternator
from them and they know it.   Your local auto parts store has alternators
with a lifetime warranty, and that's typically the smart move.


> > My local O'Reilly auto parts store has a 70-amp unit, but
> that hardly seems like much of an improvement over 65 amps.  What are my
> options for a 100+ amp unit that is a drop-in replacement for the stock
> alternator?
>
>>>It should be extremely simple to find a higher-output alternator with
the same 'footprint' as the stock one.   I've been told that Ford 1-ton vans
with the 460 typically have mondo alternators; police cars too.   They
should
be readily available from any auto parts store.   (If I'm not mistaken, the
460 and 351C use the same alternator architecture).   So just tell Cleetus
at the auto parts store that you've got a 1980s Ford one-ton van with a 460
and you should be all set.   They will probably offer up alternators with
different amperage ratings, depending on how the van was set up from the
factory.   Some were used for industrial use and had heavy-duty electrical
systems to support things like refrigeration units, etc.


> >  How hard is the three-wire to one-wire conversion if I
> wanted to go that route? 
>
>>>Couldn't be simpler.   Just hook the one wire to the alternator and
you're done.   Oh, and you have to unplug the bulb from the "GEN" idiot
light.


> >Does someone make an assembly of some kind
> that plugs in to the wiring harness in place of the voltage regulator to
> make the conversion to one-wire easier?  Does that last question even
> make any sense? 
>
>>>No. :>)

The one-wire alternators (and, in fact, modern three-wire alternators) have
built-in, internal voltage regulators.   With the one-wire setup, as
mentioned above, all you do is hook the one wire to it.   With three-wire
alternators with internal regulators, you have to re-route some of the wires
from
the stock voltage regulator over to the alternator.   That's what I have in
my
car, and although it's functionally, aesthetically it's frightening to
behold.

Some say the nice thing about separate alternator and regulator functions
is that when your regulator takes a dump, you just buy a new regulator
instead of having to replace the whole alternator.   Others argue that if
your
built-in regulator takes a dump on your new-style integrated alternator, you
get a new, free alternator instead of having to buy anything.

Given that you just bought a new regulator though, I think the smart move
would be to buy a higher-output, stock-style alternator, which would be
plug-and-play replacement for your existing one.   You don't want to go too
crazy--you don't need 150 or 200 amps.   A good 100-amp alternator will do
the
job just great!

Mike
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