Low alternator charge at idle

[Kern Dog]

I have noticed that my alternator often fails to keep up when I'm at idle with the headlights and A/C going.
The car.....

I have a rebuilt 63 or 65 Amp alternator, whatever the highest one was for these cars.

If I am idling with the headlights on and the basic stereo on, it isn't terrible. Maybe 11.5-12 volts? At 1800 and up, the rate jumps to the 13.0 and up range. Cruising at 70 mph and 2200 rpms, it is solidly in the 13.7-14.0 range whether I have headlights on or not. I do have relays for the headlights, bought from FBBO member CrackedBack.
There is something about the A/C though. That fan motor really sucks the juice. At stoplights at night, headlights on, A/C going and brake lights on I'm dropping below 10 volts. I have no electric fans or fuel pump drawing power so why is it dropping so much? Can a stock alternator be rebuilt to put out more power at idle?
Randy/ 1 Wild R/T suggested this:

These brackets allow the use of a Toyota based Denso 60 amp alternator. That is lower than stock but it probably puts out more power at idle. I'd need something with a 2 groove pulley since the A/C compressor needs 2 belts to avoid slippage.

I'm not looking to jump right into this, I'm just testing the waters,
If you have dealt with the low output at idle, what did you do?

 

[Nacho-RT74]

Is amazing with all the threads about that I know you have read still thinking on this LOL. THERE IS NO WAY a stock alt holds all the loads with accesories at iddle. Hence why the bulkhead burns with the constant back and forth loads between batt and alt.

Yes, the A/C blower is the biggest load sucker on the car. Is able even to burn the fan lever selector on 73 and lates A/C control units that took me to install a relay system, one to every blower speed (4 in total if we count the heater speed)

Is wishing stock look and no brackets deal.. Tuff Stuff 100 amps. (There are 120 units at this moment too)

This is the cheaper source I have found on the web. I whish exactly this one for me but I have a lot of priorities right now to cover right now, and since my Charger is in pieces in Venezuela yet I think will take some time to take care of this


Alternator Tuff Stuff Performance 8509DP - Pace Performance Parts

Sure they are squareback alts, not completely correct for your 70 thought, but at least 80% correct look. 100% if you don’t look at the rear case LOL.

Long time ago a member of dodgecharger.com board found me a local shop on his area able to tune up the alt for a bigger capacity output but the quote was pretty much similar to this price (plus double ride for the alt) On those days tuff stuff wasn’t on market yet, just Powermaster.

JFYI… the quickstart shop upgrade kits are not really efficient. Already tried one.

 

[Nacho-RT74]

I posted the casted original finish, but chromed and black are available at the manufacturer website. Personally I’m not a big fan of “fashionist” finishes.

(I think I was editing my post yet while you “thanked” my reply)

 

[Kern Dog]

Hmm....

I have no ammeter. The alternator charge wire runs to the starter relay in my car. There is no charging voltage going inside.
The instrument panel is a Dakota Digital.

I should also mention that I have aftermarket Air conditioning too.

 

[Don67Satellite]

I installed a Powermaster 17519 100A to replace my old 60A that had issues. Chrome, but looks like a Mopar alt. I also run relays on the headlights. Don't have AC yet, but it powers all the stock stuff, heater blower, aftermarket gauges, Progression Ignition and I am at 14.5V at idle. If I recall the tag that came on the alt (they test them before shipping) it can put out up to 73A at idle if necessary, so I never seem to drop below 14.5V. I almost put the Tuff Stuff 8509RCSP (also chrome) in but the Powermaster arrived first, so it got the gig.

 

[Kern Dog]

Thanks Nacho and Don.
I have always relied on factory type alternators that I buy rebuilt from the major auto parts stores so I'm not as familiar with the aftermarket units. It would be good to have something that fits stock brackets so if I have a failure when on a road trip, I'd have an easier time finding at least something to get me on the road again.