idle voltage

[monty76]

What kind of voltage are you guys getting at idle? with the lights on I get about 11v at idle, stoplight for instance. Car cruising down the street about 13, without lights about just a bit more, say 13 to 14. Are there any advantages to getting a constant 14v regulator?

[Ghoste]

The constant 14v is a race only piece and will boil your battery in short order.

[monty76]

FYI I'm driving a 73 se with a 440

Thanks for the info on the 14v

[twilt]

The constant 14v is a race only piece and will boil your battery in short order.

why would that be the case? offhand it doesnt make sense to me as modern vehicles typically charge anywhere from 13.5 to 14.5 V without boiling a battery.

[Ghoste]

Because they are averaging that figure in the regulator.  When those same vehicles go to a lower rpm, the charge voltage drops, correct?  A constant supply is just that, constant.  Even at idle it will be in an overcharge condition.  It's designed for race systems where they need a higher output but will only be running for a short period of time.

[monty76]

...bump...

[2Gunz]

Monty mine is about the same.

11 or 12 at idle and 14ish at 2300 RPM or so.

I once had my car out in the ran  in LA traffic with the lights on, heated on and wipers going. And guess what, the battery almost died. I had to turn everything off and run the engine a little above idle to keep the thing running will sitting in traffic.  That day SUCKED. 3 freaking hours of the car is going to die any moment now.

I decided that want going to happen again. So instead of reinventing the charging system on my car I decided to buy an Optima yellow top battery.

One of the best things I have ever bought for the car. Its prolly not the best solution, but it was easy and has SO much more life than a regular battery.

Another option might be to put a smaller pully on the alternator to increase RPM's at idle.

And I think ghost is correct about the race regulator.  Im not familiar with it, but I would suspect its not much of a regulator at all, it just puts the alternator at full steam ahead.  Which as mentioned will kill the battery.

[John_Kunkel]

Because they are averaging that figure in the regulator.   When those same vehicles go to a lower rpm, the charge voltage drops, correct?   A constant supply is just that, constant.   Even at idle it will be in an overcharge condition.   It's designed for race systems where they need a higher output but will only be running for a short period of time.

So, if one starts out on a highway trip across the country and sees 13V continuously while at highway speeds and never drops to a lower rpm except to stop for gas every 4 hours, the battery will boil?

[Ghoste]

John, are you asking me a trick question?  It may be oversimplifying the way that I have explained it but if you installs the constant output regulator, and begin driving in situations where the load is going to be less than a race environment demand, then yes, the battery will boil.

[twilt]

Because they are averaging that figure in the regulator.  When those same vehicles go to a lower rpm, the charge voltage drops, correct?  A constant supply is just that, constant.  Even at idle it will be in an overcharge condition.  It's designed for race systems where they need a higher output but will only be running for a short period of time.

Not trying to be difficult here and not familiar with this constant 14v regulator but modern vehicles normally charge at over 14v (even at idle) without any battery boiling. on modern vehicles, load and  rpm dont have as drastic effect on charging output voltages.   the only times i have seen batterys boil is when a regulator went bad and system was charging at 16v or higher. The charging voltages at idle of the 2 vehicles that i installed alternators on yesterday....... Saturn SC coupe 14.2V, Mercury Cougar 14.7V

[Chryco Psycho]

typically a battery has 13.2 v & the alt puts out 13.8-14.2 so ti will not draw from the battery but at low RPM the alt may not put out enough current to keep the battery charged , changing the regulator will not make any difference , using a higher idle speed or a smaller alt pulley to turn it faster will help though

[Ghoste]

So everyone is saying I'm out to lunch on the constant output regulator?

[John_Kunkel]

Lots of people have successfully run the constant voltage VR on the street, the big difference is at idle and low speeds where the stock VR might not keep the system at battery voltage.

A fully charged 12 volt battery will read about 12.6-12.7 volts so a 13.5 volt constant charge isn't going to harm the battery.

[Ghoste]

So why isn't it the standard equipment if it's harmless?  It doesn't cost any more to make the higher output version.  If some vehicles need it, why pay for the redundancy?
You are very welcome to run one on all of your vehicles if you choose.  I will not and I still advise against it for the vast overwhelming majority of street driven vehicles.

[greenpigs]

So everyone is saying I'm out to lunch on the constant output regulator?

Not me, I ran one of the blue race regulators,I was told it was ok  for the street, and melted wires. Those same wires had some ugly splices in them which may have been the meltdown cause. Either way Summits and Mopar Performance say that they are race only, which is good enough for me.
  It's more "juice" than the system can handle, not necessarily the battery.

[monty76]

When you said it melted some wires did you have the wiring re-routed around the amp gauge? Mine is fried so I followed the tech article and bypassed the gauge. Now I have a heavier gauge through out and I'm about to swap the the thing with an Auto Wire kit. Just ondering if a constant vr will melt that set-up

[greenpigs]

I don't think so, but they must have a reason to for saying it is a race only part. I would use a standard part as opposed to the race regulator..

[Nacho-RT74]

Is just enough go with a stock later 70s alt ( full case covering the stator ) what is able to drive around 80-90 amp  and 800 amp batt, adding smaller pulley and extra paralell wires to teh existant ones up to ammeter through firewall 8 gauge.

Cheap, easy and still will be a Mopar.

well who knows... a Mopar without charging problems maybe isn't anymore a Mopar LOL...

[G Force]

What is a "Later"  70's alternator. What ampereage do they put out?  Any model  or order number?  Any pictues?  Thanks

[Nacho-RT74]

they are able to drive around 80-90 amperes. Stator is around 2 milimeters wider but rotor, diodes, condenser, bearings, pulley are the same than earliers with squarebacks alternators ( double field ) with brushes isolators exception and cases. As far I know stator IS the big difference.

They are the ones with NON VISIBLE stator center coil, because is hidden by the front and rear alt cases.

This is the  laters 70s alternator kind (this one is painted black, but originally isn't painted )



notice that stator is hidden by cases.

[defiance]

Just for reference, my vehicles:

'92 buick: 14.4v @ idle (around 1100rpm)

'03 WRX: 14.1v @ idle (around 600rpm)

'72 Charger: 13.8v @ idle (around 800rpm)

That's measured at the battery.  The charger and buick both have high-end upgraded alternators, but the batteries in all are normal, and the one in the buick ( a cheap-o Auto Zone one) is about 4 yrs old.