Power master Alternator

I have a 65 Coronet that I recently bought and I am trying to sort out my last issue with it. I put on a set of dual electric fans and 26 inch radiator to keep it cool and settled that issue. My first night out with it the voltage regulator went out. It had a stock type points regulator on it. Right now it has a square back parts store alternator on it. I switched to a stock looking electronic voltage regulator yesterday and it is charging again, KINDA. It is only showing around 12.6-12.8 at the battery at idle, if I rev it up it goes up to 14.3-14.5 but right back down at idle. This is with the fans off. I have a new Power Master 17509 75 amp alternator to put on it but am I going to accomplish anything by doing this. Power master instructions also show to ground the extra field terminal. Right now I just want to get out and drive before the season is up but 12-8 volts without the fans on is not going to cut it. I guess my questions are.
Do I need to install a 1 wire alternator with internal regulator.
Do I need to use the one I have and ground the extra field wire.
Do I need to run a 8 gauge wire directly to the battery.

This is normal and is due to the speed of the alternator / pulley ratios



First question is what do the fans draw current wise?

Then add headlights, A/C, and other things that cause a higher draw current wise.
Now you have established what size (output wise) alternator will be needed.
Once taht is established the next step is the wiring side of things v

I don't have AC but the fans draw 12 amps each, the only other thing is the headlights. I would like to add AC in the spring but it probably wont happen

I have 100 AMP Powermaster alternator. I have SPAL 2700cfm electric fan, and A/C. With eveything on, including headlight, gauge shows little over 13. I do have it grounded with using a seperate 6 gauge battery cable. If I ever have to replace the alternator, I will go higher than the 100 AMP.
Jack

are you using a 1 wire Power master on yours. I am not against buying another alternator, I just want to drive it. The 12.7-12.8 at idle is with nothing on, not even the fans. I do have the Mopar electronic ignition on it.

Also what does it accomplish by grounding the extra field wire. Power Master shows to ground it but that just don't sound good.

Yes, it's the Powermaster 1 wire. Steady 14 reading without AC on.

Can't have too much ground. I didn't notice that PM recommended it, I just thought was good idea, so I grounded it.

I did put the PM alternator on. Im still not happy with it at idle. its around 12.8-13 volts at idle without anything turned on. with the lights on it idles around 12.4. if I give it gas it goes up fine. just not enough at idle. I started it with no ground on the field wire and it didn't charge at all. I put a 10 gauge wire on it and it started charging. do you know what the part number is on your alternator. My old 68 Charger had a painless harness in it I switched the alternator on it to a mid 90's truck 135 amp piece because of the huge fuel pump on it to feed the Procharger.

You either need a smaller alternator pulley, larger crank pulley or turn your idle speed up.

I just converted my 51 Plymouth to 12v, used a Mopar alternator and regulator, 87 Diplomat donor. 13.8-14v at idle. If I turn everything on (not much to turn on) it stays there.

The older factory alt did not put out full charge at idle. Even the output test in the service manual says run the eng at 1500 to 2000 rpm. But the newer Power Master should charge good at idle. We put this one wire 100 amp Power Master alt on my sons Dart and it puts out much more at idle as it put out 70 amps at idle when I put a load on it. We like it because it looks like a stock Mopar alt. You don't have a larger alt pulley on the car do you ? Many racers put the larger alt pulley on for more hp but it kills the charging at idle. Ron

It has the stock pulley on the parts store alternator I took off and the power master has there aluminum pulley. looks to be stock size. I am not against running a 100 amp 1 wire if it will take care of the issue. I do want it to look like a factory alternator.

Sorry, do not know the part number. It's been on the car over 10 years, maybe 15.
Jack

I just seen also that CVF racing offers there own 100 1 wire alternator that they advertise to be designed for low RPM charging. I am running there pulleys and brackets so I looked at there site to see what all they offer. They are definetly proud of them though. they are on sale right now for $255. regular is $319. Im going to see if I can find the part number for the Power Master alternator.

large pulleys on racing cars keep bearings safer at high rpms

I found that out about 15 years ago. I had a 70 Cuda that I put a 426 Hemi. Every time I really got after it I had to put a alternator on it. You would think it would turn 8000 rpm more then once before it took a dump.

per what I have read I think is good to let you know for those don't know:

The need for ground one of the dual prongs alts to be matched to earliers charging systems is because both are isolated. Rotor needs to get both fields to be able to produce electricity.

On earliers systems ( mech reg ) with one wire for field, this wire ( green ) provides a positive regulated source while the other brush is attached directly to chassis. this closes the field circuit to rotor.

on dual prongs with two wires ( elect reg ), one wire ( blue ) provides constant positive from ign switch, while the other one ( green ) is now a negative regulated source. Hence the reason to be both isolated.

There is somehow of myth about "one wire alts" being more efficient... false. is not because is a "one wire alt" but because the alt itself response better or not to the regulator or regulator is more efficient.

stock look "one wire alts" are not that the same alt with a MOUNTED ON regulator. any of us can become the stock alt into a One wire alt just getting this regulator:



which is available at several dealers. this uses just a ground source, positive source and is triggered to ON from a stator lead

Do you by chance have the part number for this? I need to figure out if it will fit in the space I have for it.

My only tip to you about the PowerMaster Alternator is this. If you think the belt is tight make it tighter, they don't charge well with a loose belt. I had a "not charging" issue with mine, I tightened the belt and it helped. I think it could stand to be tighter. PowerMaster assured me that you can't get it too tight and it won't kill the bearings.

FWIW I just changed out my Powermaster alternator (I think it was a 85 amp one) for a new 125 amp Powermaster.

My car was doing exactly what yours is and finally started trying to charge all they way up at 16 volts...Lights dim at an idle but everything worked fine once off idle...

With the stereo load I have when it is turned up I know the 85 Amp didn't keep up with the draw...I bolted the new 125 amp alternator on the factory brackets after making all new spacers on my 383.

It's a world of difference...no more low charging at idle as the gauge reads a consistent 13.8 all of the time...

The added amps allow me not to drain the battery while driving with the music cranked up...

I think the bolt on voltage regulator on mine was bad since the alternator does still charge...That may be your issue also...

Blind leading the blind.

A couple of points, there are (2) current specs for electric fans 1 is their startup rating and the other is the continuance rating...
Regarding belt tightness, the Powermaster alternator may like it really tight but the water pump doesn't...
If too tight for a longer period, get ready to replace the water pump..

Just my $0.02...

The need for you to over tighten the belt may be you have the wrong width belt. Some replacement belts are not the same width as the original which can cause them to slip. Also I remember having one replacement brand belt stretch (can`t remember the brand name at this time) causing it to loosen.

Care to explain?

I never did overcome the Mopar low voltage at idle issue using any of the Mopar alternators. I even tried the smallest pulley I could find on the alternators.

I stumbled across the adapter bracket to mount a CS 144 on my car. It puts out 135 amps at a slow idle and over 200 amps just off idle. Yes, I did upgrade my wiring to accommodate the heavier amp load by using a lot of the Mad Electric theory. . I was not after the peak output, but wanted more amps at idle.

No one has ever noticed that it's a non=Mopar unit.

I have always been able to clear up the dim lights at idle issue on my mopars, event the 51 Plymouth when it was originally 6v generator equipped. mechanical regulator, electronic regulator, single field connection, dual field connection charging setup all of them no dim lights. Gotta clean all the connections and repair them if needed.

Need to note your alt will never provide more than the car needs at iddle or revving up! You can get 800 amps alt if you want, but if your car ( along with the batt if discharged ) requires 55 amps while iddling because you have fans and whatever else, the alt will provide JUST 55 amps. The alt specs just says is ABLE to provide the output at certain speeds, but not that will PROVIDE it as a steady output.

The tests made on bench are being full fielded to provide its max output over the speed curve.

And more than voltage issue is really amperage issue, just that at certain amperage failure, then voltage begins to make somehow a proportional failure, but when you get the voltage variation, amperage began to fail way earlier.

But created few new problems.
You ought to removee the cover and see what went wrong. Even if you don't fix it, it will be useful information.

The voltage following rpm up to the set point was normal.
But at idle, with no additional equipment and battery in good condition, it should have been a little higher IMO.
Being a new to you car, its worth checking the idle speeds and the pulley diameters.
A 100 rpms difference at the crank can make 200 to 300 rpm difference at the alternator -and that can be huge!

Here's some output curves so you can see what I'm saying about rpm vs. power producing capability.
Capability is what Nacho just was describing. The actual amount of power flowing out depends on the demand.
So taking a stock '68 Coronet, demand by the coil and the rotor with engine running and battery charged, will be around 4 amps.

Hard to say. It depends on what they did to get the higher output. Sometimes to get the higher output, companies test at lower voltage. Other ways include using a more windings - which in turn draw more current resulting lower output at low rpm. In theory, if they could fit things more precisely, then the rotor's field would be closer to the stator.


No.
If you wan to use the regulator on hand, then yes the second brush is grounded.
Your car came with a positive controlling regulator. This means the regulator controls how much current, if any flows into the rotor.
Starting in 1970, Chrysler started equiping all the cars with a negative controlling regulator. It uses the voltage reading on the positive feed wire to control the negative (ground) connection of the rotor.
The question is whether your regulator can handle the current draw of the either the squareback on the car, or more so, the Powermaster. Maybe Powermaster will tell you the current draw. Good luck on finding a person at a VR manufacturer to say what any particular one can handle.
It depends on where the fans are connected in, and whether the fans will be run a lot on battery or not.
If you just neeed to get a race, or a couple weeks, you could connect the battery to the alternator output with an 8 ga. But to protect the system, put a 16 ga fusible link between the battery and that wire.

My suggestions longer term are:
A. Go back to mechanical fan, with shroud, etc. Then factory wiring scheme works pretty well.
B. Keeping the electric fans, go to a longer more efficient alternator like the Denso and alter the factory strategy. I think I would use an auxillery fuse/breaker box and relays, with one of those relays allowing a direct connection to the battery and alternator. Also I wouldn't use an AGM battery. If its getting drained from running the fans with engine off, then it will draw a bunch of amps when recharging - and an alternator that can supply a lot of amps at low rpm will cook the battery.

This is a typical late 60s stock type system showing the current flow after starting and then after battery is charged.

what Sniper said, there are 2 sizes of alt pulleys (dia) that I have seen, you want the smaller one. I'm assuming you have an electronic version of the "box" reg

Pulleys

https://store.alternatorparts.com/chrysler-square-back-pulley.aspx

This diagrams seems to be a bit familiar LOL

Yes, Nacho. Good point.

I saw that as a given, as its an inherent design feature of these system. I used to have a a way to big electric race style fuel pump, twin Spal fans that sucked nearly 50 amps on start up along with A/C, power windows, and brighter headlights. It took care of all that.

I've since switched over to the Mopar clutch fan & shroud, and put a more street friendly 2 speed fuel pump on the car. It works much better, and as you pointed out, the system automatically adjusts to the load.

YES.


I actually typed a caption crediting where each of those charts came from but the caption did not appear when I posted.

The first is yours, I forget now is that a late version squareback or the next generation of Chrysler alternators?
The other is a common GM self energizing alternator and comes from a Delco- Remy catalog. The engine rpm is based on an AMC-Jeep application.

No racers started doing that years ago to pick up a few horses by slowing the alt down and its not as hard on the rotor. Sure the bearings will spin slower since the alt is slowed down but I have not seen anyone tear bearings out of their alt with stock size pulleys when racing. I run and always have run stock size alt pulleys on my street and race cars and have never had any bearing trouble. Ron

I had a car one time that would not charge good when the eng revved up. The more rpm the eng did the less it charged. It seemed like it would be a slipping belt but it was not making any noise or squealing at all. But I noticed if I started the car and then brought the rpm's up to about 3000 rpm for about 30 seconds I could see it charging less. Then I shut the car off and felt the alt pulley and it was so hot it was almost red hot. Which was from the belt slipping of course. So I found that to be a good test when I feel the belt may be slipping and its not making and noise. Just look for a very hot alt pulley that will burn your finger so just touch the pulley real fast when doing that test ! Put a new belt on it and problem fixed. I have seen this a few times in the 40 years I was turning wrenches where the belt slips but does not make any noise. Course the key is that it charges less when the rpm's go up and it will fool you for a minute since the belt usually squeals when its slipping. Ron

I'm not claimming any credit LOL... just was fun to notice that... in any case its Beck-Arnley credit since was taken from the alt I bought from them ( via Rockauto ) coming with the chart.

BTW its a late version squareback 78 amps

according to Power Master I needed to speed up the alternator. I measured my pulleys and my crank pulley was a 5.2 diameter and alternator is 2.6. which gives me a 2-1 ratio. Power Master said it needs to be as close to 3-1 as possible. I ordered the biggest pulley I could find that's 6.4 diameter. we will see what that does

It's like deja vu all over again.

It seems the general populous thinks that alternators are supposed to put out full power at idle. I've never thought that to be the case.

I haven't found one yet that will make max amps at idle unless the idle RPM is above 1500 RPM
When Mopar introduced the alternator to all there OEM made car sin 1962 with mechanical voltage regulators that wouldn't charge at night with the lights on if the RPM where below 1000 RPM they decided to fixed that 9 yrs. later in 1971 with the solid state electronic regulators and two wire alternators that still wouldn't make many amps at low RPM

actually 70, althought some C bodies began to get elec regulators at the end of 69 production as far I read somewhere

69 Imperial had the first electronic regulator. Temperature at the regulator changes voltage, colder higher voltage and warm lower voltage.

Then why does my 65 Cuda, with a mechanical regulator, not have a dim lights at idle problem?

What RPM does your motor idle at night with the lights on?
Alll the early(pre 1970) Mopars I've owned and driven would discharge with the lights on if the idle was lower than around 800 RPM

Lots of possibilites.
Could have a good matching rotor and stator.
Could have good connections so there's minimal losses.
Might be using points ignition so minimal power draw.
Might be using the original headlamps, nominaly rated 40Watt low beam, or the typical Halogen replacements that are only 35 Watt low beam.

I don't know, but sounds good.

yes!
That's why I thought it was worth posting those output vs rpm curves.

Thing that I have debating since many years ago as many of you know, but ppl never gets it really. Then say I'm crazy and blah blah blah.

Most of ppl think a 100 amps output alt will burn everything then I ask them... how your battery able to provide 150 amps cracking power or so isn't able to burn anything around and is able to light up your 5 watts dome light without burn the bulb or any wiring installation, or even the ammeter ? no answer to this LOL, because they don't understand and never accept the load is demanded by the devices and not simply sourced by itself from the source ( batt or alt ).


if your car load demand is 35 amps, you can fit bigger capacity battery and alt output, the car demand won't change and will be still 35 amps and sources will provide just that. The deal is get sources able to give that. Stock 60s and 70s alts rated at 40 or 50 amps are able to provide around 25 amps iddling, so the battery will be sucked out slowly ( discharge reading ). When revving up, the alt will be able to source that demand and even get back the charge to the batt ( Charge reading ) but just while RPMs are enough. That constant ammeter swing is what get stressed the charging system:

Bulkhead conectors, specially black wire alt one could hold the 35 amps load from the regular load demand, but if batt is discharged giving the 10 amps the alt wasn't able to source at iddle, the alt will feed maybe the stock 50 amps at certain RPMs A discharged batt will become on a one more sucker device when discharged just like headlights could be. This makes this bulkhead terminal drives 35 amps for the car load plus the 15 amps getting back to the batt, Too much for the Packard terminal. 35 amps will be kept to feed the main splice and 15 amps will be running up to batt through the ammeter, which after year of unbalanced system, unnecesary stress causing heat, loosing everything becomes on the major failure we all know, but is not ammeter fail by itself, is the unbalanced system from factory.

To add an extra failure, electrical upgrades being sourced from batt or starter relay post. This will translate as a battery sucking power, so MORE stress to the ammeter making a "ghost" or false reading like charging.

Althought hard to beat, the ammeter is not a unbeatable gauge. Still needs attention and care. It could be built more resistant from factory but for whatever reason they weren't. IMHO the main failure on the ammeter design is get press in studs to the internal shunt ( brass, really sensible to heat ) that with constant loads could began to get contact failures causing heat, stretching parts being increased with years loosen the studs pressure from the shunt. If they were solded from the begining, nothing was happened. So this detail added to the unbalanced charging system produced all the myths and fears about the ammeter system

I got the bigger pulley in and installed yesterday. Made a big difference. I can live with the results so far. At idle with the lights on it is putting out 13.5-13.6. I can handle that. as soon as you touch the gas now it jumps up to 14.5 and stays.

it is pretty stock, right down to the factory pulleys on the alternator and crank. It is an AC car so it does have a high capacity alternator.