Stock alternator capacity?

[deecee101]

I would just like to know just how much our 2g cars can handle when running more than one amp. My plan is to get a single jl 500/1 amp, but I am considering to also step up and get a 4 channel amp as well, the 300/4, would this be overkill on the 2g cars without upgrading the alternator?
Thanks for the help.

 

[Urban_S]

I am running 2 batteries and a Rockford Fosgate 1100a2 amp(POWEer hog), and a 640watt 4 channel kenwood. So far I am not had a problem.

 

[deecee101]

Thanks for the reply, so I guess running a two amp system should be no problem. Correct me if i am wrong, but will the second battery only add to how long the system can run without the car on??

 

[Urban_S]

It does that and it acts as a capacitor. So when I crank the bass up it does not make my lights dim.

 

[dynatos]

if you're looking for actual numbers, the stock alternator is 75 amps.

 

[Gigaah]

Ahh!! a topic I can help you with. It'll just be easier to copy and past then put it in my own words.

This topic comes up a lot in here and I'm just going to go ahead and clear up some confusion. High-powered mobile audio systems are power hungry beasts. If you want your system to perform as the manufacturer intends, you have to provide ample power.

-How much power does my system need?
Look at all your components (amps, head unit, x-over, changer, etc..) and write down the OEM fuse rating on each device's power line. Add them all up and figure about 50% of that number as what your system will need to be reliable. If one of your amps has two 20amp fuses, count each of them individually. This is not the most accurate method but you will get the ballpark...I doubt most people have the tools to get more specific.

-How much battery do I need?
Enough to start your engine. This is what the battery does, nothing more. Period, anything you hear to the contrary is a myth. The competetion vehicles with banks and banks of batteries use them because they do not run the engines in their vehicles and they listen for extended periods... they INTEND to drain their batteries, you don't.

-How much alternator do I need?
After you figured 60% of your system's demand above, add about 30-50amps (depending on need here, these are not concrete numbers) and that's what your alternator needs to produce to keep up with your system. If you don't have enough alternator, you are taking it out of the battery and you'll end up stranded somewhere.

READ THIS CAREFULLY: If your alternator does not produce more power than the sum of the electrical systems in your car demand, you will hate life. Either upgrade the alternator or downgrade the system. You can't fly without wings.

-What about a capacitor?
Capacitors have one quality that the audo community likes: fast discharge. A capacitor is similar to a battery; they don't make power, they store it. A capacitor holds a large jolt of power on tap and can dump it into the amplifier when a hard bass hit comes about. Then the capacitor slowly (it's actually quite fast but much slower than the discharge rate) charges back up and sits waiting for another surge in demand. If your headlights slightly dim ONLY on big bass hits or if your big bass hits seem a little mushy but you have NO OTHER POWER PROBLEMS, you will find a benefit with using a capacitor.

Summary: More batteries don't help and adding capacitors don't help...adding either of these to an already taxed charging system only perpetuates the problem. Again, your charging system must produce more than your total electrical demand or you are draining your battery.


** so yes..more batteries is just a patch to what should be an upgraded alternator/downgraded system unless you need to run your system at a show without the engine running***

 

[FiReBReTHa]

Very Good Write up!!

took care of it completly!

 

[dont need 8]

amp 1
30 amp
30 amp

amp2
40 amp

Headunit
10 amp

110 amps total
55 amps = 50%
+30 to 50 amps

at least 85 to 105 amps needed
75 amps is stock alternator output

Doh!!! Anyone know of a good alternator that will fit my needs and not break my bank?

 

[Gigaah]

Nope. Infact if I recall when I looked years ago they were hard to find for my 90 talon.
its going to cost some $$ ($200-$350). Maybe check around locally to see if you can get one rewound? I didn't check into that and I don't know how much more juice you'll get from it. On the other hand. I did happen to run two 400watt amplifiers in my 90 talon with stock battery and a capacitor. My lights didn't really dim but I did go through alternators like every year due to the high load. I knew the "rules" but I chose to ignore them and I paid for new alternators and getting stranded every now and then..in my younger days.

Mr. Alternator
Mean Green
Stinger

**edit** If I recall there was some debate. I heard that the canadian alternator was rated at 90amps but it was debated if they were actually any different than the 75 amp us alternator. Shrug. just a side note.

 

[darkside515xx]

You should be able to run your equipment off the stock alternator. I am running 2 amplifiers, one with 60 amp fuses and the other with 40 amp fuses, plus the head unit and I have no problems. Lights don't dim at all. Most of the time, music is only playing at 10% it's maximum volume, unless a big bass note hits, so usually your not drawing that much current... when the big bass hit comes, it depletes a lot more current out of your electrical system, but not enough to drain your battery, since the alternator is recharging it, aslong as the car is moving..

 

[BlackNWhiteRS]

I have an amp that has a max draw of 160 amps, and another amp with max draw of 60. I only have the big sub amp wired to 4 ohms so the max draw is about 60-80 right now. with a total of about 1000-1200 watts. It works perfectly fine off of the stock alternator, dims just a tad when I have it cranking. I also have a yellow top battery as my starter battery. What most people need to remember is that unless your doing like SPL burps, your almost never gonna be pushing your RMS wattage of your amps, and therefore almost never going to be pulling max current.

 

[4geze63]

in canada dsms have 90 amp alts standard, both my 90s have them

 

[Slipstream]

"Most 2G turbo DSMs have a 65A alternator, but automatic models have a 75A. 1G Canadian models and the Galant VR-4 have a 90A alternator that should bolt on with little trouble, if desired."

Taken from Sean Costall's site.

 

[awd4g63]

"Most 2G turbo DSMs have a 65A alternator, but automatic models have a 75A. 1G Canadian models and the Galant VR-4 have a 90A alternator that should bolt on with little trouble, if desired."

Taken from Sean Costall's site.

I got my GVR4 alternator from Advanced Auto Parts. It's 90 amps and fit just like the stock one. This is what I'd recommend for a direct replacement.

 

[realitytb]

do you really need that big of a system? if its for show purposes, then upgrading your alternator shouldnt be an issue, as its a show car...

 

[Gigaah]

Thats like asking "Do you really need 400+WHP?". Of Course not!!! But that isn't the point.

 

[deecee101]

I didn't get a chance to reply until now.. busy with work and installing. but excellent writeup giggah... will be lots of help down the road... I ended up going with just a single phoenix gold xenon 600.1, we had our annual clearance sale so i got a pretty good deal, and I didn't end up going with a multi amp set up for now, that would mean extra $$$ cuz you just gotta go with new speakers extra wire etc etc to make the multi amp setup really worth it IMO.. i don't know yet if my headlights are dimming or the big bass hits seeming mushy haven't had much time to really test the system out, so i am not sure if i am going to be needing a cap...


thanks for all the input

 

[dont need 8]

I don't have any dimming issues, but I do want to make sure my engine has enough power to run smoothly, and I don't burn up the alternator. I also have a UDP that probably isn't helping matters. I do have a capacitor and I think the clarity is much better overall with it. It may have been the placebo effect but I had friends who also agreed that it sounded tighter and cleaner.

 

[dynatos]

as far as a cap is concerned, it's not only been proven to make a difference but makes sense too. unless you're one of those odd ones that thinks of power as 'pressure'. oh the many times i've had to talk kids out of 14 gauge power wire because they thought the 'pressure of the current would created a tighter bass'. A cap not only helps your amp perform and cleans up the sound, but also helps your car.

 

[deecee101]

does name brand really matter with caps, like if I went with a lightning audio cap versus a phoenix gold or rockford cap??