[DeTomaso] upgrading to high output alternator

[David Fisher]

Correction... I have a 140A Alt, not a 200A.


On Thu, Jul 18, 2013 at 8:52 PM, David Fisher <fisher95020 at gmail.com> wrote:

> Boyd,
>
> In addition to Jacks comments,  here are a few more.
>
> I recently went through this on my car, and there is more than one way to
> skin this cat, but if you plan to keep the original Amp meter circuitry,
> then, yes,  you should have some concern about putting in a high output
> alternator.
>
> If you look here, you will see the current loads that my (mostly stock )
> was drawing.    Note that the table says stock cooling fans, but I since
> learned they are Hall aftermarket units
>
> http://www.poca.com/index.php/gallery/?g2_itemId=38007
>
> Given that my stock setup pulls 56 amps  (12 of which were charging the
> battery) its possible your setup is drawing more than that or that your alt
> is just nearing end of life.
>
> I put a 200A alt in, but doing it again,  I would probably put 100A,  as
> 200A is overkill.   The primary reason I went with the 200A was to have
> pretty decent current at only 800 rpm, as I found I was killing my battery
> putting around town with the AC on - mostly waiting at stoplights.
>
> The primary safety issue is that if your battery is dead, or worse yet,
> you try and jump someone else's car from your battery, then your alternator
> will be putting out all the amps needed (probably at it's max) to try and
> charge your battery or jump the other guys.  The problem is that all of
> that current is passing through the ammeter circuit, which was designed for
> 75A, and (in my case) is now trying to handle 200A (max of the alt).    The
> simple, but not failsafe solution against meltdown when jumping someone
> else is to a) never do it, or b) do it only with your engine off (so the
> alt is not running).  This doesn't protect against a lot of current from
> the alt when you own battery is dead, however.
>
> My solution to this was to put a 70A circuit breaker on the ammeter
> circuit.  However,  I also ran a larger wire down from the Alt to the fuse
> box, and split the current at the fuse box so that my cooling fans and a
> couple of other high consumers do not go through my ammeter circuit, but
> get powered directly from the alt when it is on, and from the battery when
> the alt is off.
>
> http://www.poca.com/index.php/gallery/?g2_itemId=38311
>
>
> For most people,  I would probably just recommend buying a 100A
> alternator,  ensuring your connections on the back of the ammeter are clean
> and tight,  don't ever jump anyone else's car with yours running,  and you
> will probably be fine.  It kind of comes down to how much safety you want
> and to what efforts you will go to get it.
>
> After I start my car,  the ammeter shows it charging at about 50A for
> maybe 5 minutes until the battery recovers all the charge it used to spin
> the starter.  After that, the ammeter stays pretty close to 0.  When I have
> AC on and lights on an am idling, the Alt just barely stays on the charging
> side, but anything over idle and it easily handles all the loads.    I've
> had no (electrical) problems with my car since I did this.
>
> David
>
>
>
> On Wed, Jul 17, 2013 at 4:52 PM, <JDeRyke at aol.com> wrote:
>
>> There's an article in this month's POCA Newsletter on adapting a more
>> efficient internally-regulated alt to your stock wiring. The stock Pantera
>> alternator maxed out at 61 amps of current. There's an identical
>> appearing Ford
>> Motorcraft alt that put out 48 amps, so unless you've measured yours, a
>> PO may
>> have gone to Cheap Auto Parts Inc. for a 'stock replacement' and stuck an
>> undersized one in.
>> Somewhere around 85 or so amps, if you're actually using that much
>> current,
>> the drive belt system may need upgrading, as a single vee belt will be
>> hard
>> pressed to keep up. It may be a delicate balance to drive an 85-100 amp
>> alt
>> without a squealing belt (too loose), or wearing out your waterpump
>> bearings (belt too tight).
>> Also around 85 amps- if you're really using that much electrical- the
>> 'essential thingys' you've added may need their own dedicated wires,
>> sized &
>> fused accordingly. Good luck- J Deryke
>> _______________________________________________
>>
>> Detomaso Forum Managed by POCA
>>
>> DeTomaso mailing list
>> DeTomaso at poca.com
>> http://poca.com/mailman/listinfo/detomaso
>>
>
>