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Old 2nd January 2008, 01:14   #1
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Default Amplifier performace at different Volts.

Hi all,

I had a very technical query about Amplifiers. Power rating of amplifiers are done of specific Volts eg. 400 RMS @ 11 V , 800 RMS @ 12 V, 1500 RMS @ 14.4 V etc...

If i am not wrong the car batteries are something like 12 V?

So, my DD M3 amp, says that it outputs


2400 watts RMS @ 1 ohms at 12.8 V

2700 watts RMS @ 1 ohms at 14.4 V

3000+ watts RMS @ 1 ohms at 16 v

Now my question is that, if i want to run my system at 14.4 V, how can that be done? Car batteries are 12 V, do you get batteries above 12 V also? May be stupid question, but i am throughly confused.
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Old 2nd January 2008, 01:30   #2
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I think with all the electrical components of your car running fine (Alternator, Battery etc.) your car's system voltage is around 14.4V by default. Don't know what'll be the effect of the amp's load on it though.

I think LBM/Tanveer/B&T/Navin/Sam/Gunbir can explain more.
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Old 2nd January 2008, 01:48   #3
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Quote:
Originally Posted by iraghava View Post
I think with all the electrical components of your car running fine (Alternator, Battery etc.) your car's system voltage is around 14.4V by default.
I think its 12.something Volts.

Anyways, let wait for some expert comments.
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Old 2nd January 2008, 08:14   #4
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12.6-12.8 : Engine turned off, only battery.
13.1-13.6 : Car running, without heavy electrical accessories.
14.4 : HOW?

Its good that you started this topic, even I was thinking of opening a similar thread.
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Old 2nd January 2008, 09:13   #5
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Good charged battery gives around 13.2 V and after switching on the engine it goes upto 13.5-14.5 depends upon the engine RPM.
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Old 2nd January 2008, 09:27   #6
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Quote:
Originally Posted by panky12345 View Post
12.6-12.8 : Engine turned off, only battery.
13.1-13.6 : Car running, without heavy electrical accessories.
14.4 : HOW?
Older batteries / dynamos did top out at 14.4 V or so. I recall an alternator in my Padmini Deluxe (1979 vintage) which had a Prestolite alternator with an electromechanical regulator. This fellow gave 14.4V. These EM regulators had two internal settings. The first controlled the rotor excitation between on and off. Even when off the residual magnetism did give some output. This is where the second stage came in. This grounded the rotor, and came in only on light loads. It was this which permitted 14.4V.

Now with electronic regulators we have 13.6-13.8V. Strictly speaking the ideal voltage for a battery drops with increasing ambient temperature.
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Old 2nd January 2008, 09:32   #7
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Quote:
Originally Posted by panky12345 View Post
12.6-12.8 : Engine turned off, only battery.
13.1-13.6 : Car running, without heavy electrical accessories.
14.4 : HOW?

Its good that you started this topic, even I was thinking of opening a similar thread.
Slight correction:
12.6-12.8 : Engine turned off, only battery
13.1-13.6 : Engine running, electrical accessories running, battery charging
14.4 : Engine running, over-rated alternator + regulator, no other electrical accessories running (except ICE) and battery fully charged

Battery is 12V NOMINAL; does not mean voltage at the terminals cannot be more.
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Old 2nd January 2008, 11:09   #8
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deralte phappe, you are right.

my cars volatge is around 12+ volts when not running and hovers between 13.6 to 13.8 with everything running. never got 14.4v though. lol
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Old 2nd January 2008, 11:10   #9
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Fine... but what if i want to go upto 16.6 V....just a question, not my intension

Guys have bench tested the amp, and as said above it draw 2700 RMS @ 14.4 V, and 3200 RMS @ 16.6 V. So how can car electrical be pulled up to 16.6 V then?
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Old 2nd January 2008, 11:12   #10
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DerAlte is correct. Without headlights and AC running, and battery fully charged, you would get around 14-14.4V on the terminals.
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Old 2nd January 2008, 11:14   #11
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Quote:
Originally Posted by tsk1979 View Post
DerAlte is correct. Without headlights and AC running, and battery fully charged, you would get around 14-14.4V on the terminals.
Haan, thats what i am asking....that with AC on + Engine Running + ICE Installed, how can the entire system be made to operate at 14 V or 16V?
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Old 2nd January 2008, 11:18   #12
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1.U need a deep-cycle battery like the Optima yellow top.
2.U'll need an uprated alternator to churn the current to charge the battery.
If U dont do the above,U'll be using up car batteries like eveready batteries used on digicams.

LBM has lived with a similar setup.So, he'll have a lot to say here.
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Old 2nd January 2008, 11:22   #13
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The Load voltage is always less than non-load voltage at the output terminals of a power source.
So unless you have a 500A alternator, and your usage is 10A, you cannot escape voltage drop.
Ideally your voltage should not drop below 13V with ICE on.
If you are facing that, you should upgrade to a bigger alternator.

A high Ah battery is a stop gap solution.
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Old 2nd January 2008, 11:30   #14
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You cannot maintain battery voltage of 14V or higher continuous unless you are using a bank of batteries and/ or high amperage alternators and/ or serial batteries of 2-4 volts.

Your setup without any power supply enhancements will run for the most part in the 11.5 to 12.5 volts range, for short periods.
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Old 2nd January 2008, 11:30   #15
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Quote:
Originally Posted by amit_sound View Post
Fine... but what if i want to go upto 16.6 V....just a question, not my intension

Guys have bench tested the amp, and as said above it draw 2700 RMS @ 14.4 V, and 3200 RMS @ 16.6 V. So how can car electrical be pulled up to 16.6 V then?
Amit-bhai, the car's main electricals need not be pulled up to 16.6V, just the line to the sub-amp. At 16.6V your headlamps will go pop every couple of days!

One way is to mount another alternator with a full-wave bridge rectifier, with the regulator set for a different voltage.

BUT, are you sure the amp is rated to work at 16.6V without going up in smoke? Maybe you should read the fine print - it should say somewhere for how many seconds is that allowed! Amp electronics IS over-rated for safety - but SAFETY is the buzz-word.
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