Major voltage drop

[Stoneylowe]

Hey guys, I’m running around 4000rms total power to my subs and speakers, and despite having a 240amp alternator and brand new 800cca AGM battery I’m getting enough voltage drop to occasionally throw my sub amp into protect. Anybody have any idea why this might be? My research leads me to believe i shouldn’t need more than that, power wise, for the wattage I’m running. 
 

The only possible thing i could think of is because i was kinda lazy doing my grounds on my Big 3, i grounded it at the alternator bracket and the stock body ground point, which isn’t the greatest, just attaches to the core support. Could less than perfect grounds cause this type of voltage drop or do you guys have any other ideas about what could cause this? Wanted to consult the forums before i started redoing stuff. 

 

Thank you guys 

[CstrokerV]

Bad ground,  not enough electrical, short somewhere could be alot of things 

[liteblue]

yes. Bad grounds would not help any. Definitely not a short somewhere lolol. You do not have enough electrical for 4000 watts rms.

 

You only have "one battery", and only one 240 amp alt. You listed the CCA but not the AH, Amp hours are much more important when looking at car audio applications.

 

The alternator puts out 13.8 x 240 which is ~3300 watts. Your vehicle needs some of that power to function, lets say 40 amps, leaving you only have 200 amp available for accessories. 13.8 x 200 =2760 watts. An alternator cannot supply this much power all the time. It will get hot, RPM is also a major factor. You will also need a battery capable of providing 1240 watts for a prolonged period of time, ie hour. 1240(wattage required)/12.8(Resting voltage) = 96.8 amps or 96.8 amp hours in battery reserve. EVEN THEN you will experience some voltage drop over extended bass sessions.

 

The alternator is unable to charge the battery while power draw exceeds its capacities. As for "800 cca" that is a measurement over 30 seconds under load before the battery is depleted. if you are drawing anything near that for more 30 seconds then you are most likely depleting the battery.