Toyota Nation Forum banner

1 - 20 of 29 Posts

·
Registered
Joined
·
470 Posts
Discussion Starter #1
I can get a 200amp alternator for 325+installation. Does anyone know if i can beat this deal going somewhere else. This alt isn't a direct bolt on, they have to add a bracket..
 

·
TN Pussy Man
Camry
Joined
·
13,302 Posts
you could probably get yours rewound for cheaper...probably won't get 200amps, but you'll need one helluva system to use that up.....

what kind of car do you have?
 

·
Ferocious Teddy Bear
Joined
·
674 Posts
no, and no! though i would get your alternator re-wound, but that being said man, its a hot price. I just got a 220amp, though ill be using all of it =0p . For that price i would do it. Just a thought, its better to have too much than too little, i mean what if you add another 1500 in the long run, i know my system always ends up going over!
 

·
Registered
Joined
·
40 Posts
There is a lot of confusion about this topic but Ohm's Law can help us here. The amount of current demand your system will have on your charging system depends upon the amp and your listening habits.
First lets look at what your vehicle needs to run. Depending on which and how many accessories you are using, you vehicle will need 40 - 60 amps to operate.
Your amp is rated for 1500 Watts RMS @ 14.4V. Current (amps) = Power (Watts) / Voltage. To figure out how much power an amp rated @ 14.4V would do at realistic in-car voltage, multiply power by .7. (1500*.7= 1050). So lets's plug this into the formula: 1050 Watts/12.5 Volts = 84 Amps.
This is not the whole story hower. The number above assumes the amp is 100% efficient, but it's not. A design like this amp has great efficiency but when you consider the greater levels of clipping the amp will be exposed to it's efficency is about 50%. This means it will need 2100 Watts to generate 1050 (yikes). So lets see: 2100 Watts/12.5V= 168 amps plus the 40-60 amps you car needs, you need a 200 - 320 amp alternator just to feed this one amp....or do you?
You are the other factor. Your listening tastes dictate how much of that availabe power you are going to use with music. Most people will use 20% of the amplifier's power on average with music:
1050*.2=210 Watts (average)
(210*2)/12.5=33.6amps (average)
If you are like most people, you probably will not need to change the alternator if it's healthy.
Abusive poeple will use 50% of the amplifer's power on average with music:
1050*.5=525 Watts (average)
(525*2)/12.5=84amps (average)
Probably should upgrade.
The major difference between these two types of listeners is the amount of clipping they will drive their systems to. Most people will drive thier systems into clipping, some more than others. Clipping dramatically increases average power.
There are other factors that influence average power like Crest Factor of recordings but that is a different discussion.

Regards,

J Colasanti
JL Audio, Inc
 

·
Got SQ?
Joined
·
780 Posts
Ok so my gains on my sub amp is 3 to 1 un-regulated amp that is driiving 1500 @ 1 ohm, my front amp is 4 x 150 gains set at 2 to 1, the car requires 100 amps to run everything in the car. so what size amp do I need. Oh yeah, I run my system at 60-75% of the amps power all the time.
 

·
Registered
Joined
·
40 Posts
I am not sure that I fully understand your question, but all the information you'll need is contained within my post. Just plug in the numbers that you feel apply to you. It's doubtful you are using 75% of your amplifiers average power with music however...Unless you are driving around listening to sine waves or something of the like! The most abusive people out there will use 50% of the amplifier's power on average with music (volume pegged). These same people will listen to it loud and not care how bad it sounds. The transient nature of music makes this so.


Regards,

J. Colasanti
JL Audio, Inc.
 

·
Registered
Joined
·
392 Posts
Oh no. I need a bigger alt. I am the abusive type. But based on my JBL amps the 1100wx1ohm max current draw is 110. But my 4 ch. max current draw 60amps. My gains are set at 3/4 on the mono block and 1/2 on 4ch. I use 50-65% of my amps power. Maybe a little more on the mono amp. In a guesstamation what is my average current draw. Oh yeah, my car requires 50-60 amps with everything on. Let me know if you need more info to figure my average. Thanks.
 

·
Grenaded piston
Joined
·
6,580 Posts
oibone781 said:
what is clipping?
Clipping happens when you overdrive an amp.

What your doing is asking it to put out more power then its capable of.

When this happens the amp clips (runs out of power) and puts out a distorted signal.

Thats why its always a good idea to get a bigger amp then you need.
 

·
Registered
Joined
·
40 Posts
When the amplifer (not if) is over-driven into "clipping" the peak output doesn't increase, but the average energy dramatically increases. The problem with the "get more power than you need" theory is it only increases the amount of damaged caused when (not if) the amplifier is driven into clipping. People who are abusive will not stop being abusive simply because they have more power.
Here is an example with a sine-wave. The shape of the wave form actually changes and the average power doubles when clipped. More power = more heat on the speaker's voice coil. The Crest Factor of music is not as low as this, but that is a different discussion.


Regards,

J. Colasanti
JL Audio, Inc.
 

·
Got SQ?
Joined
·
780 Posts
I meant what size alt do I need, small typo there, my amps are 70% efficient according to specs, based on gain settings with sine waves, my peak output is at 70 on the HU (80 is max clipped volume), I play it at 50-60 all the time. My RMS rating on these amps are 1500 and 600 (not peak)
 

·
Got SQ?
Joined
·
780 Posts
oibone781 said:
I can get a 200amp alternator for 325+installation. Does anyone know if i can beat this deal going somewhere else. This alt isn't a direct bolt on, they have to add a bracket..
Where can you get this alt?
 

·
Registered
Joined
·
40 Posts
eddiem67 said:
I meant what size alt do I need, small typo there, my amps are 70% efficient according to specs, based on gain settings with sine waves, my peak output is at 70 on the HU (80 is max clipped volume), I play it at 50-60 all the time. My RMS rating on these amps are 1500 and 600 (not peak)
I covered all these questions in my initial post including efficiency. If you would like to change the numbers around, the math still applies.

Regards,

J. Colasanti
JL Audio, Inc.
 

·
Got SQ?
Joined
·
780 Posts
that is a very good price, what is there no?
 

·
Registered
Joined
·
470 Posts
Discussion Starter #19
if i get this 200 amp alt do i still need a five farad capacitor. Also if i get the alt, and the amp still goes into protect, i guess we can all agree that the problem is the amp, right?
 

·
Got SQ?
Joined
·
780 Posts
that would be pretty costly to find out, have the amp checked before you go drop 300 bucks...and no you will not need a 5 farad cap.
 
1 - 20 of 29 Posts
Top