Miguels Posted December 11, 2014 Report Share Posted December 11, 2014 always match the batterys..... you could get away without it..... i'm a keen believer in overkill for all my electrical. cant hurt having the extra batt in there it hurts the wallet im with addict.. a good battery under the hood and one in the rear. my logshttp://www.stevemead...-my-new-set-up/my blow through loghttp://www.stevemead...future-updates/ 96 ss http://www.stevemeadedesigns.com/board/topic/164094-96-impala-ss-build/ Link to comment Share on other sites More sharing options...
Guest Posted December 11, 2014 Report Share Posted December 11, 2014 What if I left stock battery in front and then put an XS power battery in the rear? Link to comment Share on other sites More sharing options...
Miguels Posted December 11, 2014 Report Share Posted December 11, 2014 get a agm from autozone you dont have to get xs power batteries my logshttp://www.stevemead...-my-new-set-up/my blow through loghttp://www.stevemead...future-updates/ 96 ss http://www.stevemeadedesigns.com/board/topic/164094-96-impala-ss-build/ Link to comment Share on other sites More sharing options...
Broke_Audio_Addict Posted December 11, 2014 Report Share Posted December 11, 2014 get a agm from autozone you dont have to get xs power batteriesI agree 100% if you can't swing the money for Xs power Batts just grab whatever agm fits under the hood and the biggest agm you can afford for the back.Having cheap agm's is better than nothing. I think juice box is $200 for a group 31 I'd grab one of those if I was on a budget for the back. That being said a lot of people's definition of "music" is a clipped 30 hz sine wave with some 80 IQ knuckle head grunting about committing crimes and his genitals. Link to comment Share on other sites More sharing options...
Miguels Posted December 11, 2014 Report Share Posted December 11, 2014 a group 34/78 goes for $148 at autozone last time i checked my logshttp://www.stevemead...-my-new-set-up/my blow through loghttp://www.stevemead...future-updates/ 96 ss http://www.stevemeadedesigns.com/board/topic/164094-96-impala-ss-build/ Link to comment Share on other sites More sharing options...
rockFord_Expedition Posted December 11, 2014 Report Share Posted December 11, 2014 Alot of misinformation in here. What is your OEM alt rated at? Your vehicle needs about 75%-85% of that for OEM electrical etc.. If your system is 2500W RMS then yes 2500/14 = about 179 Amps. Your amplifiers arent 100% efficient though. Even a super efficient D class amp would run in the mid to low 70's and an A/B class is somewhere in the 60's. We all like over kill right? So lets figure 60% efficiency.... 2500 out requires 4167 watts in (2500/.6) 4167W/14V = about 298A Next, if you're playing music and not sine waves your amps are running at about a 50% duty cycle. So 298/2 = 149A @ 14 V your system will need. Are you running OFC or CCA, how thick is the wire and how long are your runs? You will lose some energy in the wire. Yeah, youre going to end up somewhere close to your original figure of 179A dedicated for audio but I want to make sure you know how to arrive at that number. This is what really gets me; throwing a bank of 12V batteries at a system that you want to run at 14V will NOT help you in any way shape or form in regards to maintaining 14V. Batteries have their place, but their usefulness is often misunderstood. And yes, I would still upgrade your OEM battery to an XS power, but with the proper alternator a second battery usually has no use for playing music with the engine running. Those 12V batteries need about 13.6V to maintain a surface charge and each one will consume about 7 amps or so of current to do this so they are a small, but extra load on your alternator. In regards to a car audio system designed to run @ 14V, a 12v battery bank helps you in 2 cases: It gives you extended playing time with the engine off, and it helps with voltage drop down into the range of battery resting voltage when your system is drawing more current than your alt is putting out. In this case, more alternator is the solution, not more battery. Some people will tell you that batteries kick and and supply amperage when voltage drops below 14... they dont, because they dont store a useable charge of more than 12.6 ish. and this is the range that they become useful in car audio. Also, batteries dont react quickly to super fast spikes in voltage. Good caps (not shiny chrome ones with digital volt meters) on the other hand will rest at the charging voltage and act as a good buffer between charging voltage and battery resting voltage because music is so dynamic. I guess what I am getting at is alternators, batteries, and capacitors all have a distinct usefulness in a car audio system. One doesn't do what the other is intended for. Hope this helps. Old School/New School RF Build March 2015 SOTM Winner How to crimp large wire Link to comment Share on other sites More sharing options...
Miguels Posted December 11, 2014 Report Share Posted December 11, 2014 no one is saying to get more batteries and run stock alt. we all agree with new amp and upgraded batteries.. and again they don't have to be XS power batteries. plus current is drawn from the path of least resistance so most likely it will pull most amperage from rear battery and the alt will supply the amperage to keep that battery at the voltage the regulator is set to 2 agm batteries will be more than enough no matter the brand my logshttp://www.stevemead...-my-new-set-up/my blow through loghttp://www.stevemead...future-updates/ 96 ss http://www.stevemeadedesigns.com/board/topic/164094-96-impala-ss-build/ Link to comment Share on other sites More sharing options...
Miguels Posted December 11, 2014 Report Share Posted December 11, 2014 the reason i say that xs power are not a must is because i run 3 different brands, xs being one of them and in my daily setups i really dont see a difference.. my voltage stay the same in all 3 setups plus you cant guess duty cycle and efficiency. all amps are not the same and like it is its just a guess. if 140A was good enough then most stock alts would keep up. the fact of the matter is they dont. with 1.5 batteries a stock 135a alt suffers now please do that math again but this time use 13.4 volts which is more reasonable and you will see more amperage is needed to keep that voltage.. my logshttp://www.stevemead...-my-new-set-up/my blow through loghttp://www.stevemead...future-updates/ 96 ss http://www.stevemeadedesigns.com/board/topic/164094-96-impala-ss-build/ Link to comment Share on other sites More sharing options...
Guest Posted December 11, 2014 Report Share Posted December 11, 2014 My factory battery size in the front is 24F. So I was looking at the XS D2400. And I am running like 95% OFC, and the 5% I'm not is zero gauge with 0 to 4 gauge reducers. I know to keep the length as short as possible. The amps I have/will get are around 80% efficiency (Rockford Power/Arc Audio) so your calculations might have been little off because of that. My OEM alt is a whopping 60amps right now. It has 400 watts on it with absolutely no voltage problems or dimming whatsoever. Also, I already contacted mechman about the 320amp alternator. They said that for my particular vehicle, it is pointless to get the 320amp because at idle, the charging in comparison to the 240amp model is negligible. Mechman recommended a second battery as well. I guess I just wanted to get an opinion from more than one source. Link to comment Share on other sites More sharing options...
Miguels Posted December 11, 2014 Report Share Posted December 11, 2014 4167/13.4v because its more realistic. 315a to maintain 14v only happens in the perfect world.. no one will ever see 14v unless you dont play or dont have anything on but the engine.. hot alt charges at 13.8 and even 13.4 at times and that's not counting amp playing .. just the bass will bring it down to 13.1 if he has solid electrical. my logshttp://www.stevemead...-my-new-set-up/my blow through loghttp://www.stevemead...future-updates/ 96 ss http://www.stevemeadedesigns.com/board/topic/164094-96-impala-ss-build/ Link to comment Share on other sites More sharing options...
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