Increased Alternator Output at Idle - Opinions

[68neverlate]

Hey guys... thought I'd put this out there for feedback.  I'm interested in what you have to say...

I've been operating my '68 Charger over the past few months with the aid of a battery charger.  On a fully charged battery, I would get about 4 - 6 hours running time so long as I didn't use any power other than what the ignition wanted (no radio, headlights, blower etc).  When the battery got low, I'd recharge with a battery charger and be good for another 4 - 6 hours.  When the car was running, I observed that the ammeter never showed a charge condition on the battery, it was always in a discharge state.  With nothing else on, the needle would be just off the discharge side of centre.  With headlights on, the needle would show halfway between centre and the full left discharge position.   

I suspected a bad alternator, but replaced the voltage regulator first to ensure that was not the issue.  I confirmed it wasn't.  I took the alternator out of the car and into a local auto parts store to have it bench tested and found that it was only producing 4.7 volts.  I took it home and cracked it open to see if I could further diagnose the problem.  It turns out that it was missing one of the brushes... it's amazing it was producing any power at all (all the was touching the contact point on the rotor was the end of the small spring under the brush)!  I took it into an auto electric shop and got a quote on getting new brushes. 

So, that's the background, and here's the issue.  While I'm getting the alternator fixed, I thought I'd also address the low-output-at-idle issue that exists with our cars.  My existing alternator already has a smaller than original diameter double pulley.  That'll help somewhat.  When I discussed this with the techs at the auto electric shop they suggested a variable voltage regulator so that the field voltage can be bumped up to 14.7 - 14.9 volts to compensate.  I asked if this would compromise any wiring when at full throttle and they said it would not.     

I've read a lot of threads on this subject and know there are other ways to address the low-output-at-idle issue.  Regardless of which option I choose, I also plan on bypassing the bulkhead connector by running a 10g wire straight from the alternator to the splice under the dash.  I'm also replacing the fusible link (the techs indicated that the correct size fusible link for me would be a 14g wire... if someone could confirm that, it would be nice) to ensure I have proper protection for my wires in place. 

The wiring in my car was all replaced in a restore that was done by a previous owner some 10 years ago, so it's in pretty good shape.  It is all stock, no mods or any after market add-ons.  The car is original and I'd like to keep it that way (ie: no AC Delco alternators etc.).  My ammeter works and I'd like to keep it that way (I've read some threads suggesting a modification to bypass the ammeter).  I do have factory air on the car, but it is currently disconnected (no doubt because of the charging issue).  I would like to re-connect this at some point and get it working one day as well.   

Given the info above, and taking into account the other modifications suggested to resolve low-output-at-idle and reduce/eliminate fire hazard issues that result from large currents going through the bulkhead connector and ammeter, would you agree that the variable voltage regulator option is a good way to go?

I really appreciate hearing what you guys think.

Cheers,      

[flyinlow]

I run a Jegs 100 amp chrome single wire alternator with an internal regulator. Yea it's a chevy alt. I don't care who makes my electricity and this thing makes a bunch of it, even at idle. Got one on the El Camino. Between my Buddy's and me we have eight of them on our old cars. We even bought a spare when it was on sale for$105. When someone goes on a longer road trip they throw it in the trunk. I do have to take a little grief from them occasionally,being chevy guys.

[68neverlate]

Thanks for your reply flyinlow... I've heard this is one of the best ways to resolve the issue, but I'd really like to stick with a Mopar solution if at all possible.      Just out of curiousity, did you change any of the wiring from the alternator to the splice when you put the higher capacity alternator in?

Looking forward to hearing from the rest of you guys on other options and what you think of the suggestion I got from the techs I talked to...

Thanks for your interest!      

   

[Cooter]

Think Delco made the HUGE "Police" and HD alt. in the Mopar vehicles, so i wouldn't worry too much bout the GM one. Yep, Just simply swap in a Delco 1 Wire and charging woes be gone...Watch all your buddies bitch about idle charging problems then.

[flyinlow]

Yes I upgraded the alternator wire to # 6 or # 8 and put a 100 amp fuse on the wire. I have a trunk mounted battery. I installed a charging post near where the battery had been. This is the central point of my electrical system now. I took the ammeter out of system before I put the 100 amp in.
.
Some guys are using the Denso 120 alt.kit from Mancini. Was used on Mopars in the 90's and it looks like a small Mopar alt.

[Chryco Psycho]

Denso is the solution I was going to suggest but put a bypass 8 or 10 ga wire from the alt terminal to the stud on the starter relay so all the power doesn't go through the ammeter & firewall plug .
A smaller pulley on the factory alt will turn it faster also

[John_Kunkel]

I'd go with a Denso, lots of mounting brackets available and if you get a Powermaster it will come with an output/rpm tag.

[b5blue]

I use the Mancini Racing's 120 amp Denso "kit". Works like a charm on my 70, requires a 70 up type regulator, 60-80 amp output @ idle. Dodge is not wired exactly correct for a 1 wire alt. but it is doable and less money. I have zero mods electrically on my car and the Denso puts out so much juice you need the battery in good shape, fully charged as it goes to town charging that puppy back up. All of Nacho's upgrades are recommended under his: "Some considerations" topic. If it makes ya feel better that Denso was a "Dodge part" in the past and the included brackets and hardware are 1st class stuff. 

[Brass]

Tuff Stuff:

http://www.summitracing.com/parts/TFF-7509RESP/

I love mine.  But also run the ammeter bypass.

http://www.madelectrical.com/electricaltech/amp-gauges.shtml

[flyinlow]

Tuff Stuff:

http://www.summitracing.com/parts/TFF-7509RESP/

I love mine.  But also run the ammeter bypass.

http://www.madelectrical.com/electricaltech/amp-gauges.shtml

I like that alt. Thats the first time I have seen that. If I had not already made the upgrade to the Delco style I would consider it.  How long have you had it?

[Brass]

About 5 or 6 months.  So far, so good.

[John_Kunkel]

Tuff Stuff:

http://www.summitracing.com/parts/TFF-7509RESP/

Advertised as having an "internal" regulator..what's that bolted to the back that might not clear the head on some installations?

[68neverlate]

Appreciate the feedback guys... any comments on the techs' suggestion to bump the field voltage with a variable voltage regulator?  With factory wire routing?  with Nacho's mods?  Good... bad?

[Nacho-RT74]

I'm great and happy with "Nacho's Mod"
























































( actually is noy My mod, is just what MaMopar originally did on High output alts but refreshed and upgraded on our old and existing wiring )

[68neverlate]

As you should be!     

Regardless of whether it was "your" mod or not, I'm giving you the credit because, at minimum, you were the messenger!  Many great contributions to this site through your threads on electrical Nacho... I've read through and learned a lot from them.  Good stuff...     

Regardless of which direction I go with the alternator (MOPAR, Denso, or ... etc.), and whether I use the variable voltage regulator or not, I'll be making the modifications set out in your threads to avoid the overheating problems at the bulkhead connector and the ammeter.  I don't want to supply the fuel for a neighbourhood marshmellow roast because my wiring couldn't handle the load!         

[68neverlate]

I just talked with the tech at the local auto electric shop I've been dealing with and he explained that alternator output is determined when the alternator is at maximum RPM and that higher rated alternators actually have lower output at lower RPM because of the power "curve". 

They've recommended a lower rated alternator (60 amp) to rectify the low-output at idle problem. 

Does that sound right to you guys??     

   

[flyinlow]

I just talked with the tech at the local auto electric shop I've been dealing with and he explained that alternator output is determined when the alternator is at maximum RPM and that higher rated alternators actually have lower output at lower RPM because of the power "curve". 

They've recommended a lower rated alternator (60 amp) to rectify the low-output at idle problem. 

Does that sound right to you guys??     

   

NO

[Nacho-RT74]

+1

[flyinlow]

Any alternator has a rpm that it can produce its maximum amperage. Usually about cruise speed. At idle it will be lower and at very high rpms the alternator starts to self limit.  How much you get at idle depends on the idle speed, pulley sizes and the design of the alternator itself.
Showing a slight discharge at idle with a high electric load is not a problem with old Mopars. As soon as you start moving the rpms pickup and the alternator produces more electricity than the car demands , the ammeter shows charging, the battery is being slowly charged and life is good. Unless your Charger is a cop car or taxi you spend a lot more time driving than sitting at a traffic light, so the battery stays charged.

[flyinlow]

Trivia:

Chrysler was the first of the Big Three to switch from the generator to the alternator.

Alternators work better than gens. at low speed.

Alternator windings that get hot during power generation are in the housing, not the armature like a gen. ( you can see them on a Mopar alt.) this helps with heat dissipation.

Alternators self limit at high rpms ,so a stuck or bad regulator is not as big of a problem as it would be with a generator car.

Only the field current goes thru the brushes on an alternator, less maintenance.

[flyinlow]

Sorry,got off the point. Let me use an example. My 73 Charger. Came with a 60 amp electronic regulator system. Lets assume the alternator made 50% of its power at idle and 100% at 2000 engine rpm.

I start the car, slightly discharging the battery, the alternator starts recharging the battery                                                                10 amps
ignition                                                                                                                                                                           3 amps
I pop in a CD                                                                                                                                                                          5 amps?
I turn on the headlights                                                                                                                                                           20 amps
brakelights /backup lights as I back out of the garage                                                                                                                   10 amps
total so far                                                                                                                                                               48 amps
my stock alternator will be losing until I start driving down the road, 30 amps available at idle

Now I am going down the road, brake and BU lights off     10 amp load reduction   alt at rated rpm                                           38 amps  alt. winning
Lots of deer ,better use the high beams and turn the defroster on to clear the glass ( AC runs)                                                            20 amps
alt.just keeping up ,the battery is charged now  so that 10 amp load would reduce and the alternator would do a little better.

[flyinlow]

You can drive the car this way (we did for years). Now I add two cooling fans, 10.5 amps each and  trans. OD and lockup solonoids looking for power. The bigger alternator starts looking more attractive. It wins the power contest  more of the time. Modern alternators are rated higher and have to produce at a lower rpm with most cars using OD trans today.
I think you can get the original style alternators up to 75 amps ,which should work well unless you have added a lot of electrical demands. 

[b5blue]

  I spent many years sweating this "low idle amps" problem looking for a solution. Even waited for 8 months for Quick Start to develop their High Output Mopar Alt. with the extra windings stuffed in a stock case.     One wire Alt's looked to be an option but are not a good match for how Ma Mopar wired these cars from the factory, they are great on cars engineered for that type of charging system.
  I just finally gave up and bit the bullet and spent 250.00 for the 120 amp Denso Kit. What a change in the car! Yea you bet I make darn certain my battery is in great shape and fully charged as this thing throws out plenty of amps. I have my radio and cover plate out so I can reach in and feel how hot my Alternator gauge gets and have been checking it for about a year now to see how it does. When I've cranked the engine allot messing with stuff or let the thing sit for long periods and the battery is down the terminals do get pretty hot after 4-5 minutes of recharging. What I do (For now.) is shut it down for 10-15 minutes and it cools down. Then restart and run 5 minutes or so and if I still see if it is still feeding the battery I let it rest again. I only had to do this a few times during my intermittent crank but no start days (Due to an unknown bad splice in my engine harness at the time.) Other than this mod my 70 Chargers harness is still stock everywhere, the car now runs all systems much much better, ignition, lights, wipers and blower motor all run much more efficiently not starved for current. I'll never go back to low/weak output again. All my battery does is crank the engine and supply power to light the ignition, then it's done, my car even starts faster as Alt output kicks in while cranking, reducing draw on the battery. 
I've bought the new reproduction Alternator gauge as it's rated at 60 amps not 40 like the originals and will be installing it this winter when I redo my gauges. (That should give me a greater margin of safety along with some control relay mods and putting a primary alt. output distribution terminal close to my Denso.)   

[flyinlow]

One problem with a big alt. is the factory ammeter. If you discharge your battery to the point of of barely starting or jumping it, then you big alt. starts sending 100 amps thru the factory ammeter to recharge the battery,you can have problems. If you developed a short that was not protected by a fuse, the alt. would try to feed it. The battery side is somewhat protected by a fusible link I (#14 ?) I run my alternator charging wire thru a 100 amp fuse to the starter relay.

I liked the ammeter gauge, but they are source of problems. I don't want to run 100 amps into the dash and back out if I don't have to.

The only wayI know to have 60 amps avialable at idle is to have a 100+ amp alternator.

[68neverlate]

Reading with interest guys... all great stuff.   

I follow your example flyinlow... and can see that just sticking a larger alternator into the picture without considering the wiring and the ammeter is not a good idea.        And I do see where a 60 amp alternator might have trouble keeping up, even if you don't have a lot of extras running.

I have a question though.  Given a situation where you have a high output alternator (100+amps) and the battery is in a serious discharged state, the car is cruising (alternator is at maximum output) and the draw on the alternator other than the battery recharge is minimal... wouldn't the fusible link on the battery side only allow so much current to go to the battery before blowing therefore protecting your factory 40 amp ammeter (assuming it's still wired as per factory and the fusible links blows before 40 amps are allowed to flow in the circuit)??  As I see it, the flow of electricity has to go from alternator to ammeter back out to starter relay (through the fusible link) then to battery in order to recharge the battery.  So, wouldn't the fusible link protect everything in the circuit starting at the splice all the way to the battery regardless of where the fusible link is in the path?