80 Amp Alt enough?

[dvrmstrng 5,000+ posts]

i get dimming only noticable if interior lights are on...not even headlights at night....but thats with gains set over 1/2...for regular cruisin i have gains at 2/11 and i have no problems (1200 watts @ 1 ohm)

 

[questionaire 10+ year member]

You could lower the gains, but then your sub wouldn't be as loud

Not in my situation. If I messed with gains subs(250RMS) would blow since 1606D should be somewhere around 1400@1.3 ohm..............

 

[BassAddictJ 5,000+ posts]

i run a stock 90amp alt.......i had bad dimmage at first, went to 2 red tops and dimmage went down. Even with 2200-2500w rms with music and tests the dimmage for me wasnt any worse than it was with half that power. full tilt it stayed right @ 12v, rarely dipped below 12v. alty takes it pretty well. if you get 2 good batteries the dimmage shouldn't be too bad. just remember to turn it down at stop lights or other times the rpm's are low.....

 

[questionaire 10+ year member]

Would there be a power(torque, horse power etc.) difference using 130A with 1600@ 1.3ohm???

 

[n2audio 5,000+ posts]

Would there be a power(torque, horse power etc.) difference using 130A with 1600@ 1.3ohm???

If it's on a briggs & stratton

 

[n2audio 5,000+ posts]

Watts/volts = amps
1500W amp / 13.2 volts = 113.6 amps. Now you have to take into consideration that would be with the gains properly adjusted and the volume full tilt.

AND playing test tones. Music current draw vs. test tones is 1/3 on the high side, as low as 1/5-1/10 depending on the music type.

Plus, you didn't account for efficiency at about 75%.

So - if you want to do some ballpark calculations...

1500/.75 = 2000

2000/13.6 = ~147

147/3 (music crest factor) = 49A

And that would be absolutely slamming some bass heavy stuff.

RMS current draw at everyday volumes is likely to be in the 30-40A range.

 

[n2audio 5,000+ posts]

75% efficient doesn't mean it uses 75% of the rated watts, 75% means the amps puts out 75% of the energy input as music.
The other 25% is lost through heat.

uhh - yeah... //content.invisioncic.com/y282845/emoticons/eyebrow.gif.fe2c18d8720fe8c7eaed347b21ea05a5.gif

power out/efficiency = power in

in this case, 1500w/75% which is 2000w

so...??

you corrected me to agree with me??

//content.invisioncic.com/y282845/emoticons/confused.gif.e820e0216602db4765798ac39d28caa9.gif

 

[Mugen 10+ year member]

AND playing test tones. Music current draw vs. test tones is 1/3 on the high side, as low as 1/5-1/10 depending on the music type.
Plus, you didn't account for efficiency at about 75%.

So - if you want to do some ballpark calculations...

1500/.75 = 2000

2000/13.6 = ~147

147/3 (music crest factor) = 49A

And that would be absolutely slamming some bass heavy stuff.

RMS current draw at everyday volumes is likely to be in the 30-40A range.

So you're saying that my current alt is enough?

 

[n2audio 5,000+ posts]

I would think you might have figured out by now that it's not a yes or no answer.

It will run? Sure - and most likely run for a while. It may run fine for a long time, but it's possible your alt could be over-stressed and wear out in a matter of months, weeks...who knows.

Some people have run less and had problems, run more and had no problems at all. There are many variables.

Here's a guesstimation on the power demands...

80A alt -- general rule of thumb, 40% headroom. 80x.4 = 32A

Your amps -

1000w class D

300w class a/b

class d about 75% efficient -- 1000/.75 = 1333w demand at maximum test tone power.

1333/13.6 = 98A req'd -- 98/3 = 32A (music full volume)

class a/b = about 60% efficient -- 300/.6 = 500w demand at maximum test tone power.

500/13.6 = 37A req'd -- 37/3 = 12A

As a rough estimate you're looking at 45A at full power.

Do you listen at full power or more (clipping) all the time? Do you play a lot of bass-heavy music?

If those are both true there could be trouble.

What it comes down to is -- install it right. See how it works. It might be fine. If it's not, make improvements.