2,000 rms to much for stock alt????

Help me out, Wanting to do some upgrading on all my stuff. Total continuous power will be 2,000 rms, with original stock alternator and battery. Have a 3 farad cap, but we all know they dont do much. To much power for the alternator???

Short answer, NO. I am running just over 3000 RMS and the alternator is definately big enough.

Most aftermarket alts that advertise 160amp don't actually put that out continuously, example MSD. Thats why most guys just buy the MSD case and swap the Delco guts into it. GM alts are better.

Just make sure you run a 4-6 Farad capacitor to relieve some of the strain on your alt. I run a 6 Farad.

I'm runnin 2000 watts with a 150A Alternator and a Voltage boost mod with no Cap. Even at an idle with it cranked up, the lights don't dim or anything. I think you'll be fine.

Figured I would be fine after seeing earlier posts of you all runnin 2000 plus. Right now Im just running 600 rms and do have some light dim, but never drop below 13.5v.

Watts don't matter, they have nothing to do with your charging system. Car batteries and alternators are rated in Amps, not Watts. Amps are what's important. Check fuses on your amplifier(s) and add up their numbers. This is the max current your amplifiers can pull at peak power. Most of the time, the amplifiers will run well below this number, but when you turn it up, they can get very close to the max fuse value. Different amplifiers use a different number of Amps to make their rated power in Watts, but the car's electrical system doesn't care about anything except Amps.

Your car takes a certain amount of Amps just to run, probably less than 20. It takes a bit more at wide open throttle, even more when you turn the lights on, and a lot more to run rear defroster, etc. Most of the time, the alternator is only pushing 20-30 amps, but the more accessories you have on, or the louder your stereo is cranked, the more Amps the alternator needs to create. Our alternator can only make 140 Amps before it maxes out. When this happens, you'll notice the lights will start to dim.

If the battery is run down, it takes more amps to charge it. A weak battery can cause the lights to dim, because a larger number of Amps is required to keep the battery charged. If battery is fully charged, you can play your music louder without maxing out the alternator.

Since the car is using a continuously variable number of Amps depending on what accessories are turned on, and the condition of the battery, it's hard to say exactly how many Amps are left to power your stereo system. 100 Amps is a good target, imo. If your fuse values added together are more than 100, you'll be close to the car's limit. Most amplifiers that truly can put out 2000 Watts RMS are going to be using fuses well above 100 Amps, probably closer to 200. Obviously, this will exceed the alternator's limit. Unless you can find an amp with a 100 Amp fuse, it's time to upgrade the alternator.

Watts have nothing to do with Amps eh? Then why all the nice equations? Watts = Amps x Volts.
2000w/14v (estimated) = 142A.
Or 1000w/14v = 71A.

So how is it that Watts don't matter in relation to Amps?
I'd really like to hear this explanation......

Because you're ignoring heat.

No amplifier is 100% efficient, so the formula doesn't work. If you do the math on your amplifier, you'll find the fuse rating doesn't work with P = VI formula. This is because part of the power (not included in the Watt rating) is released as heat.

And every amp is slightly more or less efficient. Class D are 85-90% (less heat). Class AB are ~75% (more heat). Use the fuse rating and you don't even need to know the efficiency of your amp. The engineers already did the figuring to determine the proper fuse rating.

Another reason your math doesn't work is because all decent power amplifiers do not run directly on 12-15V power. They use power supplies (transformers) that boost the voltage up to 20-30V or more to produce their power numbers into 2 or 4 ohm loads. You have to consider another formula to make it work: I = V/r. Now you are factoring resistance, so you'll see that you can't make 2000 watts into 4 ohms with 14 volts.

Well if you wanna go by fuses just my sub amp is 200amp fuse. I think the other is 150amp. 350amp out of a 140 alt and it works fine with a Cap.

With respect to both of your arguements you can use that equation in some situations. Example my power 500a2 came with a print out that gave me my amps efficientcy rating, which was 82%. With that number you can still use the equation Abaddon is talking about for the said amplifier.

You can get away with it if you don't turn the gains up all the way. You're just not using all the current your amps can deliver. Or, your amps don't actually put out the power they claim.

RMS power usually draws only half of the peak power rating, so that puts you back down around 150-175 amps. Also, the battery helps you out for a while. But if you played it loud enough for long enough, the alternator would not recover.

Quote :

Example my power 500a2 came with a print out that gave me my amps efficientcy rating, which was 82%. With that number you can still use the equation Abaddon is talking about for the said amplifier.

Now he can! And his numbers will be different. I didn't say the equation was incorrect, just that it won't work without factoring the efficiency.

I was told by my stereo tech that 82% is a very good efficiency rating for an A/B class amp. Quite frankly I would be shocked if my D class has a higher efficiency than that particular A/B class amp. I would expect the D to be as efficient but definately no more. I think you would be safe to figure in an average efficiency of 65% for A/B class, and 75%-80% for D class. Its conservative but it will be as accurate as you'll get without the exact numbers infront of you.

My Nakamichi AV10 reciever has an efficiency of 78%, however I'm not certain how they classify ampilified recievers. Whether they use the same parameters or not I have no idea. I assume its different because 1 is 12v power the other is 110.

AA you may know the answer to this you said you worked for Altec Lansing.

Your RF amp is very good for A/B at 82%, but most Class AB amps have a max efficiency of ~78%, whereas Class D are usually around 90%. There is very little reason to doubt this, because just about every Class D amp is smaller, lighter, and uses smaller fuses than an AB amp making equal power. This means the Class D amp can run cooler and still make the same amount of power. The consequence is higher distortion, which is not as important for powering subs. However, there are some low distortion Class D amps put out in recent years.

Your Nak receiver uses an AB class, as it is a full range amp. Class D is mainly reserved for sub duty (more power, more distortion). The 78% number is spot on with most every AB amp out there.

The home and car audio amps aren't really so different when you get past the power supply. It doesn't matter if they are powered by 12vDC or 110vAC, the power supply changes the voltage to AC, at the needed level to produce the rated power into 1, 2, 4 or 8 ohms.

I didn't work directly for Altec, I worked for a firm that designed the cases for a line of their media speakers. I am not an electronics engineer, I'm a product designer. Most audio companies send out the cosmetic design to a consultancy rather than work on it in-house.