is this the right formula.???

[1iwilly]

this don't make sense to me cause all the question i ask were answer you need a bigger alt.
well lets re-cap the situation. 160 amp alt 2 match 1100 CCAat 32 degress and 980CCA at 0 degrees batteries.
they say the rule is WATTS-DIVIDED BY VOLTS=amps
and that for every 100watts it should draw 10amps.
OK 2x8 doing 600 to 650 watts RMS at starting volts 14.50 dropping to around 13.79 volts
600-divided by 14.50=41.3793
600-divided by 13.79=43.5097
the other way 10 amp draw for every 100 watts=60.amps
so to me i still have reserve left from alt and batt for the box to do more watts.???
but it doesn't.i either have to hit the box with higher volt to get more watts . but still not pulling enough amps
here an ex sample=if i ran 16 volts charging at 18.50 drops down to 16.80. 1000watts divided by 16.80=59.5438.amps
I'm doing this to try to understand the fundamentals. so please keep the smart to your self cause that will not answer the question.
i want to be able to understand what would be the proper equipment needed with out spending money on useless thing that won't give me more.

 

[ussixtysix]

P= power in watts divided by V= Voltage of the power supply will give you I= the amount of current needed.

then add 35% as an efficiency loss (most amplifiers are only 65% efficient)

 

[W5LZ]

Lets carry that just a little bit further.
Watts = voltage X current, that's a given. But it doesn't account for the efficiency of any load. Nothing is 100% efficient. So, measure the voltage and current with that amplifier (or radio, or light bulb, whatever) in normal use, and the output power. The difference between the power going into that amplifier/radio/whatever and the amount of power coming out of it will determine -that- device's efficiency. That efficiency will be different for each device, and each circumstance it's used in. Then, the 'numbers' should start getting closer to what you can reasonably expect, can start making more sense. Everything used in constructing electrical/electronics devices are never exactly the 'right' size. They can certainly be 'close' though, and that means the results will also be 'close', but never exactly as calculated.
- 'Doc

 

[1iwilly]

Lets carry that just a little bit further.
Watts = voltage X current, that's a given. But it doesn't account for the efficiency of any load. Nothing is 100% efficient. So, measure the voltage and current with that amplifier (or radio, or light bulb, whatever) in normal use, and the output power. The difference between the power going into that amplifier/radio/whatever and the amount of power coming out of it will determine -that- device's efficiency. That efficiency will be different for each device, and each circumstance it's used in. Then, the 'numbers' should start getting closer to what you can reasonably expect, can start making more sense. Everything used in constructing electrical/electronics devices are never exactly the 'right' size. They can certainly be 'close' though, and that means the results will also be 'close', but never exactly as calculated.
- 'Doc

the radio is a cobra 29 classic dead keys 2 watts swings bird to 8 watts rms.????? and at 600 watts the reflect is 6 watts.
so is my box doing what it suppose to do for this set up.??

 

[Captain Kilowatt]

Most amps run around 50% efficient except for some class C splatter boxes that run a bit higher. You must determine the efficiency of the amp in order to determine how much current is required for a given power output. Example: say your amp runs 50% efficient at 600 watts output with 13.8 volts. It would take 600/13.8 divided by 0.5 for a total of 87 amps.

Where this 10 amps for every 100 watts thing I keep hearing about ever came from is completely beyond me. I suspect it is another deep and dark CB related mystery that only ever seems to happen on 11m frequencies and nowhere else in the radio spectrum.

 

[BOOTY MONSTER]

use PEP watts not RMS watts . pills are rated a pep watts and audio works because of PEP watts . RMS watts is for folks blinded by the bird boys .

 

[W5LZ]

1iwilly,
That first set of numbers is related to modulation percentages (and is well over 100%). The second set deals with SWR. Neither of those deal with the efficiency of either the radio or the amplifier.
I agree with Capt.KW, that 10 amps per 100 watts thingy isn't 'real', it's just a misquote of misunderstood information.
To make it just a little bit more complicated, the input power supplied to an amplifier is in DC watts. The output power of an amplifier deals with AC watts. They are definitely not the same. DC power deals with 'resistance'. AC power deals with 'impedance'. The only similarity between those two is that "watts" name for the unit of measuring. Ain't that a thrilling thought??
- 'Doc

 

[1iwilly]

Most amps run around 50% efficient except for some class C splatter boxes that run a bit higher. You must determine the efficiency of the amp in order to determine how much current is required for a given power output. Example: say your amp runs 50% efficient at 600 watts output with 13.8 volts. It would take 600/13.8 divided by 0.5 for a total of 87 amps.
:

ok so i must be running at 50% cause thats what i get out of mine.??
i also notice with the van on or off i get the same watts
so why all this talk that you need 165amp alt to see full power out of the box.??

 

[GnG8d]

use PEP watts not RMS watts . pills are rated a pep watts and audio works because of PEP watts . RMS watts is for folks blinded by the bird boys .

If you want to take it a step further, "RMS wattage" doesn't exist

 

[Captain Kilowatt]

ok so i must be running at 50% cause thats what i get out of mine.??
i also notice with the van on or off i get the same watts
so why all this talk that you need 165amp alt to see full power out of the box.??

Near as I can figure it's because most people overdrive the amps beyond the manufacturer's ratings and try to squeeze every last milliwatt out of them and in doing so they do require lots more amps.As a point of reference any time you see me quote power output or current consumption it will be based on manufacturer's ratings of the devices used and NOT on what can be obtained by driving the snot out of the amp in order to achieve some "feel good" numbers.

If you want to take it a step further, "RMS wattage" doesn't exist

Correct. There is no such thing as RMS power. RMS voltage times RMS current equals AVERAGE power.