what size is the alternator in the tC. Reason I ask is because when I am playing my music (even when I am driving) my car will completely shut off, engine and everything. I want to put in maybe an Ohio Generators high amp Alternator however I was wondering the size of the oem alt.

if I remember correctly, it's 120 W.

Do you have a larger-than-OEM sound system running or something?

^^ I think you mean Amps, not watts. I believe it is closer to 90 or 100A. I seriously doubt it is your alternator unless you have one hell of a system. Find the problem before you start replacing parts. What kind of power are you pushing with your system?

I do have a hell of a system :). I compete in db drag/ bass race events every weekend

I know for a fact that is my alt. It just can't charge my battery fast enough. I am pushing 5000 watts

BTW I am talking amps not watts

not 5000watts on your OEM alt.

If you're competing and have 5000w worth of RMS power, then you should know that you won't be able to get that full 5000 without a helluva electrical system....what kind of wiring do you have? what kind of equipment do you have?


as engifineer said, I think the stock alt is around 90-100Amps

Amplifiers cannot produce more average energy than the alternator can provide. All enegery to move a speaker in your car comes from the charging system. Amplifers take the energy it receives and converts it to something useful to do work.

If the Scion Tc has a 90 amp Alt (I believe this to be true), that's what we have to work with. The car itself needs 40 - 60 amps to operate dependent upon which accessories you're using so this comes off the available output. If you don't use the AC/Heat and no lights, you'll be closer to the 40 amp figure. Best case that leaves 50 amps for your sound assault on the neighborhood (you bastard). Ohm's law come in handy here:
Power = Current x Voltage
Power = 50 x 12.5
Power = 625 Watts (alternators output)
As you can see, there is a descrepancy, your amps say they produce 5000 Watts but they only have 625 Watts of supply. Unless your amps have some Star Trek power supplies, you're not getting the power you paid for unless there is a rift in the space-time continuum in your car.

To make matters worse, power supplies are not 100% efficient, 50% is most common. This means that for your amps to produce 5000 Watts of output, they need 10000 Watts of input. If you were listening to a sinewave clipped by only 3dB, you would need 800 Amps of current:
Current = Power / Voltage
Current = 10000 / 12.5
Current = 800 Amps

Now I know that there is a big difference between listening to an audio system and dB Drag competition. If you're not allowed to run the engine in a competition, it's all battery. This is why these guys load up with as many batteries as possible (a tough task in a Tc). Without the alternator recharging them, the battery voltage sags very quickly. For every 1 Volt of sag, there is going to be a 15% reduction of amp output (about .5 dB) with a non regulated power supply. Also, the listening material is very different so the average energy used over time is very different (between comp and musical listening).

Another thing to consider is how the amp gets it's power rating. The industry will have you believe that a 14.4V input is valid in your car with a 12.5 Volt charging system. The good news is that if your amps use this rating, you don't have to worry about supplying a 5000 Watt system because it's only 3500 Watts, the bad news is someone is lying to you.

If you were to take another identical car with an identical system except the other car had only 1000 Watts (same amps) you would have a short burst advantage of about 4dB (until the batt voltage saged) in competition. If it were an endurance competition, the other car would have the advantage. On the street driving around listening to music, both systems would be just as loud. There is no such thing as a free lunch.

If you are actually stalling your engine with your system, I am going to assume for a moment that you're an abusive listener. Abusive listeners will use 50% of the amplifers output avergage over time. When you factor in efficiency, the current required looks like this:
Current = Power / Voltage
Current = 3500 / 12.5
Current = 280 amps
Once you add in the car's requirement of 40 - 60, you're going to need an alternator in the 320 - 340 amp range. To my knowledge, they don't make an alternator for automotive applications this big. The biggest alternator that I know of that will fit into a Scion bay is 180 amp. Maybe you can get a large case in there with enough effort and fabrication. If you did pull this off, the charging system output to the stereo (best case) becomes 3125 Watts. This would produce just over 6dB more output than you do now, but still not allow the amps to produce their rated power (real or 14.4V fantasy).

I don't know anything about your system outside of the power, but it's better to get output with displacement rather than gobs of power that your electrical system cannot support. If you were to cut your power in half and doubled your cone area, you would have the same output as you do now and the current required to produce it would be cut in half.

When the JL Audio Golf was built back in 2000 the system consisted (among other components) of two 13W7 and two 500/1. A year later when the 1000/1 became availabe, the 500/1 were replaced with two 1000/1 amps. The difference was 3dB of output an an audio system that only plays loud when plugged into a wall. This is fine for a demo car that spends it's life connected to two 100 amp power supplies in a convention center, but not a daily driver (the extension cords become a _____).

Finally, if having a car loaded with audio gear resulting in a curb weight equal to the space shuttle was not bad enough for MPG, a bigger alternator is also harder to turn for the engine creating more drag. Soemthing to consider these days. In audio, there's still no replacement for displacement!

:clap:

Thank you...I'll be here all week....Remember to tip your waitresses.....

First off, JLTD thatnk you for replying to my post with much detail.

I guess I chould have added some more info...

I am running two Kinetik batteries right now. A 1800 in the front (replacing the OEM batt.) and a 2400 in the trunk (hatch)

I am running a 5000W Orion HCCA amp, powering (2) Orion 10" H2's wired down to 1/2 ohm.

Also as for my competitions I do bass race (I said db Drag just because everyone has heard of that) In bass race you can run your car and rev up to 2k rpm. However you score is based on a 30 second average of continuous playing music (not a bass note).

Any suggestions of what I can do to help power my car more?

The only amp Orion amp I could find that matches what you say that you have is the HCCA D5000. Is this the amp in question? According to the specs on the Orion website, this amp is 2500 Watts RMS @14.4V into a 1 ohm load. It does not say it's 1/2 ohm stable. The specs that I am looking at are here: http://www.orioncaraudio.com/amps/Dmono.asp
It has the "Max Power" spec listed at 5000 Watts. These specs should always be ignored because they are pointless.
The drivers that you have are listed as a D2 subwoofer so it would be possible to wire two of them to a .5 ohm load (or a 2ohm load).

As I stated earlier, the alternator is the source for the electrical energy in the car and no amount of extra batteries is going to change that. Extra batteries only increase engine-off listening time. If you're allowed to run the engine during the comps, you want the system to run off the alternator. The batteries at one point need charging and that means an additional load on the alternator. The reality is the extra battery is actually REDUCING the available voltage to your system. Remember that every volt is worth .5dB!

Get the biggest alternator that you can shoe-horn into the bay, get rid of the extra battery and you will see your scores increase. An old trick is to outfit the alternatror with a smaller pulley so it spins faster at idle. It's not great for MPG or alt longevity, but it allows the alt to keep up as best as possible.

:bow: Thats the best explaintion of anything on this site that I have read. I think we all learned a little something from reading that. :bow:

JLTD good info man.

Shameless plug i hit 139db@42Hz (termlab mic) with my RFT10001bd w/ 12" RE SX in a 2cuft ported box.

I want it to hit louder but that means a new box and that means no back seat (no trunk as it is right now). :doh: But i am considering to build a box just for competition but not sure what to build.

i hit 142 @ 50hz with a termlab mic

What are some places to get aftermarket alternators? Where can this 180A alternator be found?

there is a company called Iraggi altinator that builds great alt's, call them at 615-287-7991 and talk to Dom. high output altinators and ohio generators also makes high output alternators. check out www.dbdragracing.com and do a search for those companies.

this post is a great starting point for anyone planning out a system and using your car's available power wisely. well-done! i still want to get a HO alternator though :D

ok so im gonna go get a new amp within the coming days. its probably gonna be a memphis 16-mca300 which has 2 25A fuses. does that mean it draws 50A all the time whenver its running, or how much would it normally draw? the amp will be 200 watts rms x2 channels (this is at 3 ohms). i have an mtx ta3404 right now that has the same thing...25x2, but i keep hearing about the alternator goin bad and all this stuff and im gettin worried. ive also been hearing that the car takes 15A from the alternator? im assuming that there is no way that's true...that it has to be at least 40A? please help im so confused!

^^ in your situation, I wouldn't worry SO much... running less than ~800RMS with your amps shouldn't be too big of a deal. Even though your amp is rated for 200x2@3, it might only be pushing 50x2@3 with the HU volume 1/4 of the way up. This is because the voltage sent to the amp (dependant on HU volume) directly effects the watts being pushed out the amp.

A 400watt amp at 50% efficiency with 12v will only be pulling 16-17 amps at full tilt... If my equation is correct...<<< It wasn't...

Some of the best things you can do are: upgrade the Big3, upgrade the battery, make sure all connections are adequate.

aight thanks!

To produce 400 Watts output @ 12V and the amp is 50% eifficient, 66.7 amps would be needed. If this same amp was in someone's system and they were listening to music (or whatever you kids think is music today) and the person was an abusive listener the average demand would be 32 amps.
A normal listener would drive the system to draw 13.4 amps.

The difference between the two profiles is the amount of clipping the listener will drive the system to. Abusive listeners will use 50% of the amplifier power with music average over time. A normal listener will use 20% of the amplifier power over time with music. Amplifiers which are 50% efficient need to draw twice the power rating to produce the rated power output, the rest is wasted as heat.

The formula is Power / Voltage = Current.

OK, I just did my math wrong..haha..

shouldn't it be
(watts/voltage)/effeciency = amperes? I think I did (watts*effeciency)/voltage=amperes....

BTW:
Class a/b amps are typically 50-60% effecient
Class D amps are typically 70-80% effecient

that's just a generality though... some could be lower, some higher

Class D amplifiers are generally used in subwoofer applications. Although their design offers greater efficiency than A/B amplifiers, they are also driven into higher levels of clipping than other amps due to our lack of sensitivity to low frequency. Even "golden eared" audiophiles will commonly drive their subwoofer amplifiers to 10 - 15% distortion. Obviously, by using Class D you're still ahead in the efficiency game, but it real life Class D is on par with A/B amps in efficency. If you were using an A/B amp on your subwoofers the efficiency would be far worse, but you would have higher damping factor generally speaking. With few exceptions, Class D offers higher efficiency than A/B, but almost no control due to the switching design.

That's why it's good to use an o-scope to find the max unclipped gain level, then set it to your likings under that setting...

There is a couple other things here to. Alot of the issues that people run into also is that they will run there amp wide open. (gain all the way up). Alot of people think the gain is a volume knob. The problem with that is the gain is to level match the headunits output and the amps input. When the gain is wide open and you are already running a high output deck you are clipping your amp before you ever really get started on the output. This causes the amp to work harder and causes more distortion. Therefore pulling more current from the electrical system.
Another issue is people running there amp at a lower ohm load then what is recommded cause it "makes more power that way". That is not true. 90% of the time you are not making more power, you are just increasing the distortion rate of the amp. The speakers are now taking all the abuse. Your speakers wont like it, your amp wont like it, the charging system wont like it.

The key to any system is the charging system. The system can only do what it can with the right backing. Putting a cap or anything like that in a lacking charging system will usually only put more of a strain on the system. They are more like a band aid. They will help in some situations, but wont fix a bad cut. LOL.

Using an O scope to set gains is not a bad idea at all assuming you own one and know how to use one. For the other 99% of the human race that listens to music in their cars this practice would have no impact.
Also, using the Oscope to set gains has nothing to do with what the end user will do with it. I don't know anyone who would be happy with the output of a zero-clipped system. Everyone drives their system into clipping (even you), some more than others. Clipping is a way of life today as many recordings have such a low crest factor that they are clipped before the CD (or itunes downloaded) is even played.
Using and O scope or multimeter to set gains is a great way to manage clipping but you want to allow for some overlap to allow for moderate clipping (what all humans do) and avoid severe clipping where things start burning.
A great method to set gains if you don't have an Oscope is illustrated here: http://mobile.jlaudio.com/support_pages.php?page_id=143

Look for MEAN GREEN alternators...they make bad a** off road ones that last forever

I need help... My stock stereo is hooked up to my 2 10" JBL subs with 1200wat amp. all installed by cartoys. When am sitting it sounds fine and when i start moving the bass gets a lot louder and doesnt sound too good. but if am sitting and hit the gas in park or neutral the bass doesnt change so i thought it might be a power problem but am not sure now. I need help on what is going on. Does Scion stock stereo have a road noise inside the stereo or is it the battery, alternator, not enough power or what???? Someone help....

hey man, which year is your car? cuz i know for 06' have a diff radio that has an ASL level. its pretty much used in the way so that the volume goes up as the car moves to compensate for "wind" noise on the highway and such. if ur car is an 06' and up, turn off your ASL, and you should be good.

Same thing happen to me yesterday, car completly shut down in the middle of the road. i had subwoofers turned off thou but i was driving in traffic with the ac on. I couldnt get my car to turn on for an hour figuring out wtf happen. First i thought it was main fuse blown, but it was fine. I took a look at it today to see wut went wrong with my multimeter.

The problem wouldnt repeat but i turned of ALL my accories including ac and lights. Car wanted to stall a few times and got this low voltage reading http://i2.tinypic.com/4pl1kt5.jpg I also heard the altinator making clicks. After a few seconds voltage went up to normal http://i7.tinypic.com/4z419b6.jpg sorry i dont have AMP clamps for the multimeter for more testing.
What should i do?? buy used eom alternator or buy a higher amp alternator? I have a lot of leds/neons everywhere, navi, subs, gauges, radar, etc.