Maximum Wattage Available in 12v system?

[cherrybomb]

Back when I was installing stereo's, and studying for my MECP, I remember there being a calculation that basically determined the absolute maximum wattage you can extract from 12v.

Probably used the OHM's law to arrive at it. But for the life of me, I cannot remember how it was calculated.

Anyone else know this off the top of they're heads? Or maybe a little better at math than I am?

 

[cherrybomb]

Using Dead Link Removed ohms law calculators, a 12v system, pushing 100 amps, is only capable of 1200 watts..

Using the following formula.
P is "Power" or "Watts"
E is "Volts"
I is "Current" or "Amps"
P = E x I

So, if your pushing anything north of about 700 (real) watts, it makes good sense to have a high output alternator, and a cap, or two.

 

[TeamPwnageBrad]

Youve gotta also remember, amplifiers are not 100% efficient. If your amp draws 120 amps and is getting 14.4 volts in, it could put out 1728 watts at 100% efficiency, however it isnt. At 70% efficiency, it would be producing around 1200 watts. Also when playing music, you arent going to draw nearly as much current as if you were playing a test tone at 100% volume.

 

[cherrybomb]

True..

It's just interesting. Since some people boast several thousand watt systems, which, in all reality, can't actually be done, unless they're running a VERY strong alternator, or a pair of them, etc.

You're quite right, that it is NOT always drawing that much power, but technically, it does have a cap.

 

[TeamPwnageBrad]

me and my buddy are running several thousand watts, 6000 at one point, but we do have a 5500 amp battery bank at our disposal lol.

 

[93exploder]

yeah, its called having more than one battery.

 

[expo5.0]

i'm claiming 8k watts.

doubt me?

 

[Longjohn119]

From 12volts - 8-10 watts, 25w bridged .... before you freak out this is a FACT because with 12 volts you can't apply more than 12 volts peak to the speakers ...

That's why the older 'booster amps" where only rated at 25 watts (on a good day). What manufacturers do to get around this FACT is use DC-DC converters to up the 12 volts and make it a split supply, for instance to get 50 watts into 8 ohms you need approximately a +/- 35 volt supply (70 volts total)

What you REALLY want to know is how much power you can get from the **available current** in car battery/alternator system.

BTW most high power car amps that are blown are caused by the DC-DC converter toasting and often times taking out the power amp transistors in the process. Seldom do you see a blown outputs without a blown converter but you do find blown converters with perfectly working amp section.

Low distortion power amps are easy to design and make 'bulletproof', it's the converters in the best units that make the real difference in durability but seldom do you see anything written about or the specs for them ...

 

[cherrybomb]

i'm claiming 8k watts.

doubt me?

I've seen the pictures of your truck, and buildup. I saw the row of batteries under your box.

I doubt nothing! ;-)

 

[Saleen_SR71]

i'm claiming 8k watts.

doubt me?

rms or peak?

 

[expo5.0]

since there is no way to determine peak on an equitable basis i'm claiming 20k peak lol