how big high output alternator

[MOHpro]

My total system rms wattage is 2900. The total combined amps of all the fuses on the 3 amps i will be using is 315. I will have a new main battery and 2 additional batteries in the trunk to power my amplifiers. How big of a high output alternator would I need to run the system and all the vehicle's electrical systems?

[Clownrock95]

What vehical?

What batterys?

Wire runs?

Current alt?

Most will say the biggest you can get from a reliable seller

[CPT.scratchandsniff]

more advanced members feel free to chime in but from my knowledge, charging system size "should be" as follows...

your 2900w output (assuming that's total RMS output of all amps) is after factoring in your amps efficientcy. for this example we will assume 80%

2900w devided by 0.8 (80% efficientcy) equals 3625 watts required. generally speaking, 10W=1A wich puts your alternator requirement at 362A

this is assuming your playing a burp note at 100% output, however playing music (at a more normal volume) will give the ALT. a period to catch up between bass hits.

having said that if you could get ahold of like a 250A ALT. I would feel confident saying your headlights "shouldn't" dim (when playing music). this is however just theoretical and only real world testing can tell for sure.. im far from experienced when it comes to installs but If a more experienced member cares to comment id like to hear what they have to say. hope this helps

[DubNDodge]

You know my rhyme and reason to buying an alt? Get the biggest one that fits and call it a day. you're going to upgrade eventually and when you do, you don't have to buy another alt