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Do I need a high output alternator?

 

New member
Username: Tre607

Canton, Ohio United states

Post Number: 1
Registered: Dec-04
I have an 1993 chevy cavalier and I just put in an Optima yellow top deep cycle battery in it. I have two Audiobahn ALUM15Q 15" subs and an Audiobahn A1300HCT amp. the subs are rated at 1100 watts rms and the amp is rated at 1200 watts rms at 1 ohm. I was wondering if I would still need to install an high output alternator since I have a battery that is made for this type of abuse?
 

Bronze Member
Username: Terminatermule

Australia

Post Number: 31
Registered: Nov-04
Hi Tom,

Mate thats not how it works :-) - the battery is only the reserve capacity, it can't run your system for you. If you draw more amps then you put in then your bat will go flat - no matter what you buy. Someone please post Tom those links on charging circuits :-). Tom once someone that has them bookmarked posts them for you have a read and it should become clearer what you need.

Cheers Glenn
 

Gold Member
Username: Glasswolf

NorthWest, Michigan USA

Post Number: 6043
Registered: Dec-03
Alternators and Charging Systems

Upon reading and answering many questions about car audio, one question always pops up:
"Do I need a high output alternator or just a capacitor?"
If you want a killer system, you may think that all you need are big amplifiers and huge speakers. Not so! Adding a bunch of car audio components to your vehicle without the proper charging system may lead you to disappointment, distortion and damaged equipment.

Let's say you install a 1,200 watt amplifier in your ride. Your rides charging system must produce enough electrical current to run the amplifier. Now how do you know how much current is needed? Simple: divide the RMS power rating of the amplifier by the amount of voltage your cars electrical system will produce then add in amplifier inefficiency based on amplifier class.

Most vehicle electrical systems are 12.5VDC at idle, and between 13.8 and 14.4VDC above about 900rpm but we use 12 volts as the standard for these calculations, so 1,200 watts divided by 12 volts equals 100 Amperes of current. If this is a class D amplifier, it'll be ~80% efficiend, so we'll add 20% of 100A to the total, and we get about 120A of current demand continuously at peak amp output. This means that the electrical system of the vehicle will need to produce an extra 120 Amperes of electrical current to power your amplifier and subwoofer at peak levels. Keep in mind that the factory electrical system is designed to produce enough charging power (alternator and battery) for the vehicle's stock equipment, and was not designed to accomodate high-powered audio systems.

The biggest mistake made by consumers and (some) installers is failing to beef up the charging system to handle the extra load of the audio system. First, you need to understand how the electrical system operates. This must be one of the most mis-understood systems of the entire vehicle, so here's a brief summary:

Turning the ignition key begins the process of cranking the motor. The battery supplies the power to get things started. Once the engine is running, the electrical burden is shifted over to the alternator. The alternator uses the engine's mechanical power to produce electrical (AC) current. The AC current is passed through a rectifier and changed to DC current which is then sent through a voltage regulator to smooth out and set the voltage rails for the car . The alternator also has the duty of recharging the battery after starting the vehicle by providing a forward bias voltage higher than that which the battery produces on it's own.

Everything works perfectly so long as the power requirements of the vehicle do not exceed the capabilities of the alternator. If the peak output is surpassed due to excessive load, then power will be pulled from the battery. If the alternator and battery combined cannot meet the demand, then the vehicle's voltage rails, and subsequently the electrical devices are diminished (dimming lights, spark plug misfires, audio distortion and amplifier clipping, or even the car stalling.)

The first place to look to determine if your charging system is up to the task is the alternator itself. If possible, look for the HOT RATING on the alternator. IF you can't see it easily, call a local auto-parts store or car dealership and ask them to look up the stock alternator size, or rating for your vehicle. The hot rating will tell you the amount of power the alternator will produce once the engine reaches it's operating temperature (this is a lower rating than the cold rating). I suggest using your stock alternator unless you experience problems. That's how you know if you need to upgrade, since there is no concrete way to tell if a stock alternator has enough reserve to handle your additional burdens. Now, if you do need a new and larger alternator, after finding the stock rating, then allow your alternator about 10 Amperes credit or buffer area.
As a note, when calculating your required current for your audio system, this is an easy way to do it:
1: calculate the total RMS wattage of your system based on how the amplifiers are wired (2 Ohm load, 4 Ohm load etc)
2: take that total RMS rating, and divide by 12 (volts.)
3: add 20% for class D and T or 40% for class AB. (this compensates for efficiency based on amplifier topology)
4: add amplifier totals together for a combined measurement. (in amperes)

This is how many Amperes your audio system will require in addition to what your car already needs (stock alternator rating) at full output.

For more information on charging systems and alternators, see here:
http://www.bcae1.com/chargin2.htm
 

Silver Member
Username: Carguy

Post Number: 659
Registered: Nov-04
Glasswolf, you need to a link set up so that you don't have to repeat it over and over like that Energizer bunny commercial. Of course unless you like typing :-)
 

Gold Member
Username: Glasswolf

NorthWest, Michigan USA

Post Number: 6050
Registered: Dec-03
actually that was a direct paste from the article on my site.
I paste the link over and over, and I just assume this guy doesn't like linking to go read..
so I saved him a click and pasted it directly here.
:-)

article link is:
http://www.wickedcases.com/caraudio/charging.html
 

New member
Username: Tre607

Canton, Ohio United states

Post Number: 2
Registered: Dec-04
Thanks everyone for the advice. Is there any web sites I can go to for a high output alternator? I really don't want to pay way too much money for one.
 

Silver Member
Username: Carguy

Post Number: 669
Registered: Nov-04
Hey Tre607, try 4alterstart.com.
 

Gold Member
Username: Glasswolf

NorthWest, Michigan USA

Post Number: 6055
Registered: Dec-03
or just look at the "ads by google" bar on the right.
lots of alternator shops listed there.

this isn't a cheap hobby. If you want a high power system, it costs money to feed it if you don't want to have problems.
 

New member
Username: Hiamps

Miami, Florida USA

Post Number: 4
Registered: Dec-04
Tre607
Send me a email. I can get yopu the HO alternator you need. autoelectricpart@aol.com
 

SNIP929
Unregistered guest
Whats up, I have a problem like this myself, I have 2100 watts total, out of 3 amps, one 1000 watt, one 600 watt, and one 500 watt amp. The 1000 is pushing two 12's and the 600 is pushing two 10's. The 500 is pushing my highs which are two 6 x 9's and two 4 x 10's. I have a 2 Farad Capacitor. Everything electrical wise works fine in the truck when I'm in park with the engine at idle speed. I just boutght a new Die Hard battery with 660 cranking amps. I bought this because the system drained out the old battery. Anyway, when I'm in park and engine on idle speed, when I turn up the volume the battery meter drops from a full 15 volts to the red line immedietly. Even when I'm going down the road at 60 mph the battery guage on the dashboard is still jumping up and down with the beat of the music, and its not the vibration making it do either. Now from what I know about cars/trucks, electrical stuff etc. Obviously I need a new alternator, I just need to know how many amps is suitable for my set up. My stock alternator is 100 amps, and thats in a 1994 Chevy K-1500 Blazer Full Size 4x4 2 door model.
What alternator size in amps do you suggest I get that can handle the truck electrical system itself like the A/C, Windows, Head Lights etc., and that can handle my 2100 watt stereo system? I would really appreciate anyones help. Thanks

John
 

Bronze Member
Username: Hiamps

Miami, Florida USA

Post Number: 21
Registered: Dec-04
SNIP929
Wish engine has your Blazer 4.3 , 5.7, or 6.5.
I'm sure you need a HO alternator.
Send me all your Blazer information to autoelectricpart@aol.com and I'll get back to you wish the information for the alternator you need.
Aldo
 

Gold Member
Username: Glasswolf

NorthWest, Michigan USA

Post Number: 7399
Registered: Dec-03
Alternators and Charging Systems

Upon reading and answering many questions about car audio, one question always pops up:
"Do I need a high output alternator or just a capacitor?"
If you want a killer system, you may think that all you need are big amplifiers and huge speakers. Not so! Adding a bunch of car audio components to your vehicle without the proper charging system may lead you to disappointment, distortion and damaged equipment.

Let's say you install a 1,200 watt amplifier in your ride. Your rides charging system must produce enough electrical current to run the amplifier. Now how do you know how much current is needed? Simple: divide the RMS power rating of the amplifier by the amount of voltage your cars electrical system will produce then add in amplifier inefficiency based on amplifier class.

Most vehicle electrical systems are 12.5VDC at idle, and between 13.8 and 14.4VDC above about 900rpm but we use 12 volts as the standard for these calculations, so 1,200 watts divided by 12 volts equals 100 Amperes of current. If this is a class D amplifier, it'll be ~80% efficiend, so we'll add 20% of 100A to the total, and we get about 120A of current demand continuously at peak amp output. This means that the electrical system of the vehicle will need to produce an extra 120 Amperes of electrical current to power your amplifier and subwoofer at peak levels. Keep in mind that the factory electrical system is designed to produce enough charging power (alternator and battery) for the vehicle's stock equipment, and was not designed to accomodate high-powered audio systems.

The biggest mistake made by consumers and (some) installers is failing to beef up the charging system to handle the extra load of the audio system. First, you need to understand how the electrical system operates. This must be one of the most mis-understood systems of the entire vehicle, so here's a brief summary:

Turning the ignition key begins the process of cranking the motor. The battery supplies the power to get things started. Once the engine is running, the electrical burden is shifted over to the alternator. The alternator uses the engine's mechanical power to produce electrical (AC) current. The AC current is passed through a rectifier and changed to DC current which is then sent through a voltage regulator to smooth out and set the voltage rails for the car . The alternator also has the duty of recharging the battery after starting the vehicle by providing a forward bias voltage higher than that which the battery produces on it's own.

Everything works perfectly so long as the power requirements of the vehicle do not exceed the capabilities of the alternator. If the peak output is surpassed due to excessive load, then power will be pulled from the battery. If the alternator and battery combined cannot meet the demand, then the vehicle's voltage rails, and subsequently the electrical devices are diminished (dimming lights, spark plug misfires, audio distortion and amplifier clipping, or even the car stalling.)

The first place to look to determine if your charging system is up to the task is the alternator itself. If possible, look for the HOT RATING on the alternator. IF you can't see it easily, call a local auto-parts store or car dealership and ask them to look up the stock alternator size, or rating for your vehicle. The hot rating will tell you the amount of power the alternator will produce once the engine reaches it's operating temperature (this is a lower rating than the cold rating). I suggest using your stock alternator unless you experience problems. That's how you know if you need to upgrade, since there is no concrete way to tell if a stock alternator has enough reserve to handle your additional burdens. Now, if you do need a new and larger alternator, after finding the stock rating, then allow your alternator about 10 Amperes credit or buffer area.
As a note, when calculating your required current for your audio system, this is an easy way to do it:
1: calculate the total RMS wattage of your system based on how the amplifiers are wired (2 Ohm load, 4 Ohm load etc)
2: take that total RMS rating, and divide by 12 (volts.)
3: add 20% for class D and T or 40% for class AB. (this compensates for efficiency based on amplifier topology)
4: add amplifier totals together for a combined measurement. (in amperes)

This is how many Amperes your audio system will require in addition to what your car already needs (stock alternator rating) at full output.

For more information on charging systems and alternators, see here:
http://www.bcae1.com/charging.htm
http://www.bcae1.com/chargin2.htm
 

New member
Username: Pimpin

Fort atkinson, Wi Usa

Post Number: 2
Registered: Jan-05
why do u need a Optima yellow top deep cycle battery? is it better or something? why wouldnt just a battery work. i mean it does cuz thats all i have in my cars and my shuff hites hard.
 

Bronze Member
Username: Mrdark

Post Number: 26
Registered: Dec-04
ha ha Glass! that was funny...some people just can't read the first time..
anyway I need an upgraded high output alt for my 1999 Maxima. Aldo, help me...I'm looking to get at least a 180 amp alternator. I know other Maxima owners want the same thing, so it's a business opportunity for you.
 

New member
Username: Tre607

Canton, Ohio United states

Post Number: 3
Registered: Dec-04
the optima batteries are way better than regular batteries because they use a different technology than the standard batteries everyone else has. the stuff thats in the optima batteries is a film like substance that forms a jell when it comes in contact with the electrolite or acid that they put in batteries. regular batteries have these plates that produce electricity when it comes in contact with the acid or electrolite or whatever that stuff is called. with the optima batteries u dont have to worry about the battery sulfating neither. sulfating is corrosion on the plates inside the batteries when it gets drained too many times. you dont have to worry about that with the optima batteries because there is no plates. plus with the optima batteries u can mount them anyway u want. u can mount them upside down, on its side, or upright. now the yelleow top is a deep cycle battery and deep cycle battery drains slower than just the regular red top optima battery. they use deepcycle batteries in boats so u can keep the boat lights on all night without draining the battery. its great for car audio use too according to the optima website. i learned all that i know about the differences between regular batteries and the optima batteries from automotive school that i am currently attending. except for the use of the deep cycle battery for car audio use. they dont teach that in automotive school.
 

iKe
Unregistered guest
Sounds like you got suckered. Like it says above....the Alternator powers your system. NOT YOUR BATTERY! I swear....DO PEOPLE READ??
 

New member
Username: Treeguy2oo4

Phoenix, Arizona USA

Post Number: 10
Registered: Feb-05
wow you guys its all good any thing that heips you have more power wy not do it. me i'm going to do all i can to use it all. more its better!!!!!!!!!!!!!!!!!!!!
 

New member
Username: Vicky

Paso robels, Ca USA

Post Number: 1
Registered: Feb-05
DJ is my faverit player person please E-mail me
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