High Output Alternators

[Ron Burgundy]

Just curious really...

When does one become needed/necessary?

Obviously running major audio/lighting upgrades, but where does it become noticeable or worth the money?

I've read stock puts out 90 amps. If stock was made to produce 90 amps, is that to say that ANY addition requiring the slightest bit of electrical draw would benifit from the addition of a higher output alternator. Or for that matter, what if you have ZERO upgrades. Would a higher output alternator benefit you?

Looking around i've seen a 160, a 190 and even a "UP TO 200" amps opiton offered. At what point is it just overkill?

Thoughts? Anyone running one or done some additional research?

[Pathfound49]

Good Question. I believe my '03 Pathfinder has a 110 amp alternator. The problem with it and a 2 amp stereo system like mine is that at idle, the electrical system only puts out around 20 amps of usable current. High output amps bump up that output at lower rpm's. A stock alternator will power most audio systems without dimming lights and screwing up a voltage regulator if you can maintain about 250o rpm's.

I also would be interested if anyone has found a reliable supplier of high output alternators.

[scaramoche]

Here is my opinion.

First Im making the assumption that the "stock" alternator has more than enough juice(amp's) to fun stock electronics with some to spare.

What is the limiting factor is what your usable wattage is. The formula for calculatting what you currently have available (ie total wattage created by your alternator) is
Voltage X amps = Wattage.

since all alternators are 12v(roughly) the only value that changes is how much "amps" it sources.

so for standard alternators at 90 amps the wattage is

12v X 90A= 1080 Watts

Now here is where you question "Do i need to upgrade amps?"
well lets take an example.

You purchase a new stereo system. The "wattage" of it is listed on the box
Stereo=100watt
Amplifier=500 Watt

so to find out how much wattage you need for bolth devices, just add the watts together
100 + 500 = 600

Now your old alternator has 1080, to run this new stereo and not cause issues with other equipment, you need an additional 600watts. If not you will see flickering lights, and possibly other devices faltering or failing(not having enough wattage, putt's alot of strain on the alternator/voltage regulater)

So my suggestion would be to "upgrade" your alternator.

for example a alternator capable of an output of 160amps will give you the following Wattage
12v x 160amp= 1920Watts.

This is more than sufficient to run devices.

Hope this helps

[Ron Burgundy]

Pathfound49: I have read something along those lines as well. Do you notice any decline in quality of electonics or engine performance when you are at idle then?

scaramoche: Very interesting...That definately helps a lot. Its just hard to gauge considering I don't know how many watts the car's stock electronics used. For example, I have pretty close to zero electronic upgrades in my car. The only electronic mods even made are interior LEDS and a higher output headlight bulb. Yet if I turn my headlights and interior lights on and THEN start my car I can clearly see the light output decline as I start my car. Granted it returns after the car has started - but for the sake of argument, it seems like it shouldn't happen if the stock alternator was qualified to run stock equipment.

[Pwnin O'Brien]

So I've been following this thread and I think I should chime in. The alternator on your 99.5 is a Hitachi model rated at 90A (@ 12V), however, the regulated voltage is set at 14.1 - 14.7V. This means that when the car is running, and the alternator is charging, it is going to set the entire vehicle voltage charge to somewhere between 14.1 - 14.7V. When the vehicle is not running (or when it is being started), the vehicles voltage charge will be at the battery voltage which depends on your battery. Now, 90A is more than enough to run all electronics on your vehicle from the factory without a problem.

One indicator that tells you to upgrade your alternator is when you can drain your fully charged battery in a short period of time while the vehicle is running. So for example, if you have a fully charged battery, you start the car and you run all of your accessories and you go for a drive and the battery dies during the drive (and you know the battery is not at fault), then that means you definitely need an upgraded alternator. Of course, it may happen over a longer period of time, not just a single drive. Each battery has a specified capacity, generally this capacity is rated a AH (or amp-hours). That capacity dictates how long you can run the battery at a specific current draw without any outside charging (AKA the alternator). If your vehicles current draw is greater than the alternators current output, then you will eventually drain the battery.

By upgrading the alternator you want to increase the current output to make it greater than the vehicles current draw so that the battery can stay charged at all times. It's also important to note that with a sound system, the current will fluctuate and at times may draw more current than calculated, however if it goes above the intended current draw for only a moment then the alternator will simply recharge that lost capacity. It is also important to note that the power output of an amp is not related to the current draw. Yes, the power equation is charge x current = power, however an amplifier is just that, it amplifies the signal to generate more power. So for example, if you have an amplifier rated at 1000W @14V, then one might think the current draw for that amplifier is 71.43A, when it is not. That is the current which the amplifier feeds, when in reality it may only draw 10A to make the 71.43A supply.

As for your headlamps dimming when you start the vehicle, that is perfectly normal. The starter requires LARGE amounts of current to start the vehicle and it is normal for lights/accessories to dim when starting. One way to prevent that from happening is to purchase a battery with a higher cranking amps specification. Since the vehicle is not running already, the alternator plays no part in the starting of the vehicle, it is purely the battery powering the starter and all accessories. You may have read on the forums not long ago about Qxxx4's issue with his battery, he had a lot of dimming when he listened to music, that was caused by a battery with a low amperage output. By upgrading the battery, he was able to prevent a current shortage.

I know this is long a boring and it might not make much sense, but let me close with a short example.

I will use your Pathfinder as an example. So if your Pathfinder has zero electrical add-ons, you might draw an average current of 40A when driving (radio on, headlamps on, etc). The alternator is able to put out 90A, so you aren't even touching the battery really. Let's say you were to add some off-road lights, a really powerful sound system, and some other various accessories. Now you're drawing 95A (average) from the battery, now you're pulling 5A more than the alternator can support. Those 5A will come from the battery, reducing the available capacity. Now depending on the battery capacity, you may not have any problems until a week later, when you have reduced the capacity of the battery down to 0AH and the vehicle has died. You find that even if you jump start the vehicle it dies, so you take the battery to a shop and they charge it off the vehicle. Now you can drive the vehicle more and the same problem happens a week later. Now if you were to upgrade your alternator to a 110A model, you would be charging faster than you would be consuming, so the battery would always stay charged. Now, you may have that one song with the really low bass note that causes your amp to draw more current, but you are still in the clear since you have those 15A of buffer, meaning you can safely add more accessories to the vehicle.

Let me know if this doesn't make sense.

[madpappi]

^^^^ good info
i have a couple of points to chime in on also
1. do the big three upgrade the wiring from the alternator the ground and the engine ground it helps alot
2. battery battery battery do not be cheap get yourself a good size deep discharge battery
3. watch volume while idling no matter how much $$$ your alt cost @ idle you will only get a fraction of its rated power unless you change the pully.
4. if you have a ho alt do not be afraid to add a second battery (dry cell never install a "wet" battery inside your car)

[Pathfound49]

Scaramoche's reply is indeed true. The only problem is that an alternator is only producing its nominal amp rating at a ridiculous rpm. How many people drive around at 5,000 rpm?

Regarding my vehicle. I have an optima yellow top which is more than sufficient for my system. At idle, with the sub-amp working extra hard. Say listening to anything with a heavy, steady bottom end. The headlights and cluster lamps will dim slightly. As for a decline in performance, I can't honestly say other than a slight fluctuation in idle rpm which is not present with the music down. With the tunes cranking at those volumes(preferably Killswitch Engage-the double kick drum is insane, or Black Label Society), I notice nothing but turning heads and lots of ear ringing.

[scaramoche]

Having your "light's on, with all acc" is not dependent on the alternator when starting your car. This is completly dependent on your car battery. If you are noticing a dimming, struggling to turn over, the cause is that your battery cant produce enough current. In these situations you want to upgrade your battery, to one that has more "cold cranking amps".

Also, they are correct that the alternator only produces the "max current" at high rpm's. Still, the formula for wattage is correct(even when alty is running at 14v, just replace voltage in equation).

Also led lights use very little power, usually less than 1/2-1/4 watts. now your headlights is a different story, they can have very high wattages.

From a design standpoint(Im an electrical eng) Nissan probably created the electronics, and wattage raiting to be able to have everyhting on, and the vehical still start and run, with some wiggleroom(we design around tollerances). But as you begin upgrading aftermarked electronics, you wattage consumption will go up. Soon you will find that you are beyond the tollerances, and though some devices will continue to preform, others will not(specifically digital electronics).

[Pwnin O'Brien]

Also, for future reference, here are the hot output currents for each RPM range on your 99.5:

• - More than 23A current output at 1,300 RPM's

• - More than 65A current output at 2,500 RPM's

• - More than 87A current output at 5,000 RPM's

So you can see that the alternator never really reaches the full 90A until you are past 5,000 RPM's.

[Ron Burgundy]

Thanks for the info guys! Really good stuff...

Like I said, to be honest I'm just curious - I'm having no electircal problems in need of a higher output alternator.

However, I am in the market of replacing my battery and cables and figured I'd get a good idea of the entire system while i'm at it.

So basically what i'm gathering here is even with accessories along the lines of Empty V's (sound system, lighting) and maybe even a little more - a capable battery is more than enough to take care of the job? (Speaking in terms of Pathfinders/QX4s in particular - not concerned with other makes/models.)

Thanks again!

[Pathfound49]

I love the way the mod always backs stuff up with numbers, pics, links, whatever. Pretty damn cool. I'm too lazy to look all that up.

[Chuck Tribolet]

One thing to remember about your stereo is that the wattage on the box is the wattage it SUPPOSEDLY PRODUCES.

SUPPOSEDLY because the stereo makers are notorious for fudging their numbers to the high side (or even lying
like crazy)

PRODUCES because stereos are less than 100% efficient, and so will consume more power than they produce, and it's
the consumption that affects the alternator.

And don't think: OK, I just won't turn it up all the way. There are some amplifier designs that actually consume
more power at low output than at high output (though these would be a bad idea in a modern high-output
stereo for a car).


Chuck

[ganesh21]

Good Question. I believe my '03 Pathfinder has a 110 amp alternator. The problem with it and a 2 amp stereo system like mine is that at idle, the electrical system only puts out around 20 amps of usable current. High output amps bump up that output at lower rpm's. A stock alternator will power most audio systems without dimming lights and screwing up a voltage regulator if you can maintain about 250o rpm's.

I also would be interested if anyone has found a reliable supplier of high output alternators.

here is two reliable supplier for HO alternator:

http://www.mechman.com/
http://www.excessiveamperage.com/price_quote.htm

96 - 99.5 alternator - up to 200 amp @ 80 amp at idle (direct bolt on)
00 04 - up to 250 amp @ 90 amp idle (direct bolt on)

Oh yea, I have a 200 amp alternator for 96 - 99.5 pathfinder if any is interested.

[scaramoche]

One thing to remember about your stereo is that the wattage on the box is the wattage it SUPPOSEDLY PRODUCES.

SUPPOSEDLY because the stereo makers are notorious for fudging their numbers to the high side (or even lying
like crazy)

PRODUCES because stereos are less than 100% efficient, and so will consume more power than they produce, and it's
the consumption that affects the alternator.

And don't think: OK, I just won't turn it up all the way. There are some amplifier designs that actually consume
more power at low output than at high output (though these would be a bad idea in a modern high-output
stereo for a car).


Chuck

This is very true. Infact one reason to purchase stereo gear from a Well known company is because generally the the wattage listed is accurate. what you want listed on the box is what's called Watt's RMS(root mean square), this wattage is actually the "usable" wattage. Many cheap manufactures, and some well known will list one of 2 values. watt's Peak(which is about 40% less wattage), or Peak to Peak wattage, which is 80% less.. Their really is not regulation to force these guys to list a "standard", ie RMS.

[miamiheat3332]

ganesh, i checked the links you gave us, and the first one mechman, they sell it for 1997-2003, but it says for the 3.3l engine only which is not good because most people here with a 2000 or 2001 + have 3.5l

and i couldnt really find anything on the 2nd website.

[ganesh21]

ganesh, i checked the links you gave us, and the first one mechman, they sell it for 1997-2003, but it says for the 3.3l engine only which is not good because most people here with a 2000 or 2001 + have 3.5l

and i couldnt really find anything on the 2nd website.

Give Nathan a call at excessive amperage. I pick up a 250 amp alternator from him last year, around march.

[Chrisbalkissoon]

Good Question. I believe my '03 Pathfinder has a 110 amp alternator. The problem with it and a 2 amp stereo system like mine is that at idle, the electrical system only puts out around 20 amps of usable current. High output amps bump up that output at lower rpm's. A stock alternator will power most audio systems without dimming lights and screwing up a voltage regulator if you can maintain about 250o rpm's.

I also would be interested if anyone has found a reliable supplier of high output alternators.

here is two reliable supplier for HO alternator:

http://www.mechman.com/
http://www.excessiveamperage.com/price_quote.htm

96 - 99.5 alternator - up to 200 amp @ 80 amp at idle (direct bolt on)
00 04 - up to 250 amp @ 90 amp idle (direct bolt on)

Oh yea, I have a 200 amp alternator for 96 - 99.5 pathfinder if any is interested.

Is it still for sale

[EdBwoy]

Chris, welcome to the forum. I see you've began familiarizing yourself with our features such as the SEARCH

That posting was about 7 years ago, and ganesh hasn't logged on since late last year. This doesn't necessarily mean the alt is no longer available. Since new members don't get access to private messaging features until they get 10 posts, I'll send a PM to ganesh on your behalf and we'll hang tight while waiting for a reponse.