Alternator Upgrade

[280~Master]

I just bought an alternator for the 75 280Z. I got the Alt for a 82ZXT internally regulated of course 60AMP. I am not in need of it yet but have noticed a flux in voltage when driving so I am preping for when it does go out. My question for this thread is.

1. Is there a way to ugrade the insides of the Alternator to get a max output of voltage. I do have an Alt shop close by but he's not the best guy to talk with. I also don't want to spend the 100 or so for the other guys super AMP alternator.

[hls30.com]

John,

I have a book called "Alternator Secrets" I bought it years ago from Lindsay Publications-I'll see if it has what you need...

Will

[Nissanman]

An alternator usually outputs a maximum of around 14.2V, generally 13.2-13.8V.

The internal windings and diode characteristics dictate what sort of current it can produce.

So, while an alternator can be tweaked to produce more power, it is the current capability that is increased, not the output voltage.

That of course leads to the next question, why do you need more alternator output power?

Unless/until you fit an aftermarket sound system or some other power hungry accessory, the original alternator power should be adequate.

I know a lot of folks fit seriously large alternators to old cars, for whatever reason, but unless you have a need for that extra capacity, it doesn't get used.

You also need to consider the likelihood of the increased alternator output overloading the factory wiring loom.

Wiring that was designed for an 85A alternator for example will, without suitable protection, burn out when connected to a 100A alternator and the load is also increased:finger:

Ideally, the additional load should be via new, correctly protected and dimensioned wiring, directly from the battery post.

[Zs-ondabrain]

Or more basically put, Don't push your luck. Don't expect your garden hose to handle the output of a pressure washer. It was built for 3 to 7 PSI, NOT 1200 PSI. See what I mean??

An increase of 20 amps is more than plenty for what ever you're running. I have a 70' 240Z with the 280ZX 60 amp alternator. I also have 90/100 H4 lights, 55 watt fog/driving lights, 800+ watt stereo system, power windows, power locks, full alarm system, DVD player, under dash monitor, Honda wiper motor, honda blower motor and some other goodies. And I can listen to the stereo with both subwoofers going, for over 2 hours, and still start the car afterwards with NO problems.

And I've never had a power or lack of power issue. Never. Just make sure all of your power wires are up to spec, your grounds are godd-clean and tight,and all your connections are clean and tight.

You don't want or need any more than 20amps over stock.

JM2CW,

Dave.

[280~Master]

I see where you guys are coming from on the AMP's. I am running an electric fan that draws a bit of amps plus a stereo and I am headed for more power using options. Windows, Wiper pgrade things like yours dave. I do see the voltage gauge when using lights blinker ect. pluse like to much is being drawn. May just be an old regulator. But I also have some idea about things and would love to read that book Will.

[Zs-ondabrain]

Anythin being drawn off the fusebox will show up on an amp meter and things that draw directly from the battery (like my upgrades) rarely show up on AMP and Volt meters.

Make sure your fan is powered directly from the battery, via a Hi amp relay. If a typical relay is not strong enough, you can use a starter relay like those in older cars, just make sure it has a long duty cycle so it don't burn out.

Dave.

[240ZMan]

Do you see the ammeter pulse with the changing load at idle, or when cruising (such as above 2k rpm)? If it's only at idle, upgrading to the ZX alt will help a little, but not a lot. At idle the alternator just isn't able to put out as much current as it can at higher rpms.

You might want to make a list of all your planned electrical upgrades and how much current they draw. The total will give you a good idea if the ZX alt will meet your needs. Of course, keep in mind that electric windows aren't used continuously, but if you want to be safe, factor in your headlights on highbearm, the cabin fan on high, etc. In other words, use the worst case scenario.

If you decide the ZX won't be adequate, there are several options, including a few discussed on this site. FWIW, when I converted to megasquirt I found that the ZX alt was at its limit when driving on a warm night with the cabin fan on, the e-fans running for the AC, high beams on, and all the load the FI system added, including the second fuel pump. I noticed that the alt was beginning to give off a slight smell - I think it was running at its limit. Swapping to a maxima 90 amp solved it. I didn't see any point in trying to fit a new alt into an old case - too much work and chance for error.

An unexpected benefit was that at idle the new alt can put out more current. If I keep the idle at 800 rpm the lights just barely dim at stoplights. And my low beams are 80w

[240ZMan]

Anythin being drawn off the fusebox will show up on an amp meter and things that draw directly from the battery (like my upgrades) rarely show up on AMP and Volt meters.

Dave.

Actually, I have to disagree with that. On my 73 the ammeter measures current flow into or out of the battery. Under normal operations (engine running long enough to have replaced whatever current was used to start the car), the ammeter stays in the center (zero) position reflecting that there is no current flow to the battery. The alternator is supply everything required by the car. If you add an additional load to the battery, such as an e-fan, the current pulled by the fan will shown on the ammeter as "charging". The electrical system will think that the battery (actually the e-fan) is requiring the current to be recharged. Technically, as long as the total current doesn't exceed the max of the ammeter, you won't hurt anything, but under normal conditions your ammeter won't read zero either.

Perhaps what you meant to say was to connect the high load items (using a relay of course) directly to the output of the alternator? That way you don't overload the stock wiring (easy to do) and yet the ammeter will still function properly.

[280~Master]

240ZMan

do you have any info on that upgrade? I know about doing that upgrade, was even going to do that upgrade. I just don't want to change things like ALT pully and make a new braket ect. I want a good bolt on swap.

[240ZMan]

The alt I used was from a 90 Maxima (Autolite #14661). The pulley did have to be swapped and since the connector is different, I had to create some short jumper wires with the appropriate spade connector crimped on each end. The main reason I chose the Maxima alt was that there was no grinding or cutting of brackets etc and the old alt could always be reinstalled later.

Note: I'm assuming you have already made the wiring change required for an internally regulated alt.

If you do go that route, here's how to connect the 2 jumpers:

- The Field wire (green) is connected to the upper/outer connector when the alternator is viewed from the front looking up at it (from below the car).

- The N (sense) wire (yellow) is connected to the lower/inner connector.

I'm sorry I don't have any pictures as my camera was away being repaired while I did this project.

[Nissanman]

Here is a similar topic discussed previously: -

Ammeter Question

Essentially, the ammeter measures what is going into or out of the battery, NOT the load on the electrical system.

[if it did measure the total load, then, yes, it would have to be ranged to match the capacity of the alternator].

The ONLY time an ammeter DOES measure the total load, is when the engine is OFF and the ignition is ON.

In this case, it will read "-" always, since the storage battery is DISCHARGING.

So, in a normal system, the battery is a storage device which provides a ready current source to turn the starter.

Also, it provides enough reserve to power up any electrical circuit/accessory, including the alternator exciter windings, until the alternator starts to function at a certain RPM.

Then the alternator can take over the load, which may only be 20A or so, right up to its' rated capacity under extreme conditions.

What you then see on the ammeter, is not that total load, but the charge current that the alternator feeds into the battery, the trickle current.

This current is determined by the potential difference of the battery voltage to the alternator voltage, the potential difference, PD.

The storage battery is nominally 12V, the alternator normally supplies a voltage of 13.6 - 13.8V.

Hence the flow of current INTO the battery or ammeter reading slightly on the "+" side of "0'.

In a normal system , a simple test to demonstrate the workings, is to have the engine idling with a "+" indication on the ammeter.

Then, switch on the headlamps.

You will observe a quick but definite flick of the ammeter back to "0", maybe even go "-" but it will recover and settle back to the small "+" value.

This is the alternator not supplying the extra load, the battery supplying the shortfall current, the regulator sensing the increased load and then compensating for it by increasing the alternators current output.

Quid pro quo.

If the ammeter doesn't settle back to the "+" reading, there is a regulatory/charging issue.

If you don't already have one, the installation of a maxi-fuse/fuseable link on the output of the alternator, to match the cabling rating is alwas a good idea.

A 85A alternator will make short work of a cable system with a rating of 30A.

Any fuse is there to protect the wiring, period.