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[CarAudioAddict 10+ year member]

To find out the amperage draw on an amplifier takes its output power (RMS for average draw and total for max draw) and devide by 12. This will give a reading assuming the amp was 100% efficient. Now you have to consider that class AB amps are only about 60% efficient and class Dare about 80%. Divide the number of amps you got from the last equation by the efficiency of the amp and you should end up with a fairly accurate number.

so, amperage draw equation:

( output power / 12 ) / effeciency = amperage draw

example using a 1000 wattt class AB amplifier @ 60% efficiency

( 1000 / 12 ) / 60% = ( 83.333 ) / 60% = 138.9 Amps

 

[CarAudioAddict 10+ year member]

Yes you are right. I wasn't thinking.

About 99.9999999999% of the charging systems out there are 14.4 volt

Just substitute 14.4 everywhere I said 12

so, amperage draw equation:

( output power / 14.4 ) / effeciency = amperage draw

example using a 1000 wattt class AB amplifier @ 60% efficiency

( 1000 / 14.4 ) / 60% = ( 69.444 ) / 60% = 115.74 Amps

Yeah that other number looked a little high. thanks Jmac.

I must have been thinking car=12Volt. Thats a common analogy and although not very accurate is what many people think.

 

[n2audio 5,000+ posts]

operating voltage is mid 13's