watts to amps?

[hondarider 10+ year member]

How do you figure out how many amps and amp will take from your alternator?

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[squeak9798 5,000+ posts]

How do you figure out how many amps and amp will take from your alternator?

To find actual amperage draw:

(Power output/amplifier efficiency)/Voltage input = Amperage pulled from electrical system

Amperage * Voltage = watts

Lets take an example; 1000w RMS amplifier that's 75% efficient running off of a 13.8V electrical system.

(1000/.75)/13.8 = 96.62A total amperage pulled

13.8V * 96.62A = 1333.3w total watts pulled

So, it takes 1333.3w (96.62A @ 13.8V) to make that 1000w out of the amplifier.

 

[PhatTonyDeMarco 5,000+ posts]

To find actual amperage draw:
(Power output/amplifier efficiency)/Voltage input = Amperage pulled from electrical system

Amperage * Voltage = watts

Lets take an example; 1000w RMS amplifier that's 75% efficient running off of a 13.8V electrical system.

(1000/.75)/13.8 = 96.62A total amperage pulled

13.8V * 96.62A = 1333.3w total watts pulled

So, it takes 1333.3w (96.62A @ 13.8V) to make that 1000w out of the amplifier.

So if I have a 2000w RMS amplifier receiving 14.0v and it is 70% efficient then...

(2000/.7)/14 = 204?....

 

[psych0ticnemes1 5,000+ posts]

****.... i would need one hell of an elec then lol

 

[squeak9798 5,000+ posts]

So if I have a 2000w RMS amplifier receiving 14.0v and it is 70% efficient then...
(2000/.7)/14 = 204?....

Yup. It'd draw 204A from your electrical system with 14V input at full power output.

 

[UndercoverPunk 5,000+ posts]

Yup. It'd draw 204A from your electrical system with 14V input at full power output.

Which rarely happens daily.

 

[psych0ticnemes1 5,000+ posts]

man... i guess if you want any kind of power over 500rms you really NEED a HO alt

 

[UndercoverPunk 5,000+ posts]

man... i guess if you want any kind of power over 500rms you really NEED a HO alt

Maybe if you're diving around burping full bore constantly...

 

[psych0ticnemes1 5,000+ posts]

Maybe if you're diving around burping full bore constantly...

well if you want a 1000rms woofer to get a 1000rms from a 1000rms amp... that's 90 amps of current... most stock elecs can't handle that... so your sub won't even recieve it's rms...

 

[UndercoverPunk 5,000+ posts]

well if you want a 1000rms woofer to get a 1000rms from a 1000rms amp... that's 90 amps of current... most stock elecs can't handle that... so your sub won't even recieve it's rms...

In most installs with gains set at 0db subs never receive their RMS anyway... Even if you set your gain with an o-scope it's not going to be doing 1000RMS all day long...

 

[squeak9798 5,000+ posts]

Which rarely happens daily.

Tru dat. Tru dat.

 

[PhatTonyDeMarco 5,000+ posts]

I have a 220A alt from Nathan, and I have been getting some dimming at higher volumes, I was thinking I could try a new battery (I am using a 7 year old stock battery.) I was thinking getting a yellow top, and I have done the big three..

And where would I find out the efficiency of my amp? I just took your 70% Squeak... I looks on the Planet Audio site and there was nothing on that.

 

[squeak9798 5,000+ posts]

I have a 220A alt from Nathan, and I have been getting some dimming at higher volumes, I was thinking I could try a new battery (I am using a 7 year old stock battery.) I was thinking getting a yellow top, and I have done the big three..

And where would I find out the efficiency of my amp? I just took your 70% Squeak... I looks on the Planet Audio site and there was nothing on that.

PA might be able to tell you.

Beyond that, your only option would be to measure the input voltage and current draw in relation to the power output via sine waves and DMMs/clamp meters.

 

[maylar 10+ year member]

You guys forget that music has about a 5:1 peak to average ratio. Nobody listens to sine waves at full power (well.. not for long anyway).

Divide your calculated numbers by 5 and you'll have an idea of what the electricals need to provide with real programming.

 

[PhatTonyDeMarco 5,000+ posts]

Would Advanced Auto or something like that be able to check my alt for its output? I want to make sure the amp really it putting out 220A...