560ti Posted July 16, 2020 Report Posted July 16, 2020 First post on the forum. I want to do an audio system later this year. Nothing super crazy maybe 1500-1700 watts RMS total. I have gotten quotes from alternator companies and they look good (Singer, DC, and Mechman). I plan on buying one of the 3 alts and doing the big 3 wiring under the hood. The question I have is I replaced my battery 6 months ago with a standard autozone battery (Duralast Gold). When I did my last system I had Singer alternator with an actually AGM battery since that was what was recommened for car stereo systems. Do I have to replace the Duralast battery or since the alternators are going to be way more powerful than my current draw could I technically get away with the Duralast gold ? (basically will I still be susceptible to harash voltage drops regardless of how badass the alternator is ?). Thank You
1point21gigawatts Posted July 16, 2020 Report Posted July 16, 2020 You don’t need an aftermarket alternator or a better battery when it comes to only 1500-1700 rms. That’s a waste of money on that type of rms. Just do a big 3 upgrade and possibly an extra agm battery in the rear, at the most. “How can we help you?” “And don’t forget to tell them that the customer isn’t always right.”
Backwoods Posted July 16, 2020 Report Posted July 16, 2020 So much is dependent on the vehicle you have and the electrical draw for its stock components and the stock alternator size... I personally feel like anything over 1500rms should have upgraded electrical... But a 200amp alternator and adding 50-75AH to what came stock would be plenty... OK, so first things first... Lets start with if you had no system at all... A stock lead acid battery is designed for cranking amps, and normally doesnt have a very large reserve, and amp hours are relatively low. An alternator runs the vehicle while its on, the battery cranks the vehicle, the alternator is only designed to run the electrical components and recharge the minimal drainage caused by cranking the car, not charging fully drained batteries. Charging drained batteries puts added stress on an alternator and can make them fail prematurely. Now lets add in the system... And factor in a bit of the stock electrical draw... Lets say your stock alt is 80 amps, your car needs 60 when the AC is running, using power windows and headlights are on... Lets say the reserve capacity on the battery is 65ah, not unusual.... Now you have 1500rms drawing 150 amps... Do the math... 150 for the amp +60 for the car =210... stock 80amp alternator + 65 AH from stock battery = 145... Now your stock battery is draining and the stock alternator is required to work even harder, straining it and causing wear that could be prevented by upgrading electrical... All that being said, you wont be pulling 1500 watts after rise, its rare you will be using the full draw for stock electrical components, and you could likely get by just fine without upgrading, but i still feel its best to upgrade with anything over 1500. In auto tech and performance college we were taught one of the main reasons alternators fail is from being in charge mode too often, for too long.... PLUS, upgrading will help your amp get the 14.4 volts while playing, which will give you closer to their rated power than running them at 12-13 volts. Singer 250amp Alt, Singer PCM bypass harness Titan8 Lithium Underhood safe BCI PWR-S5 Big 3 W/ dual runs of power/ground. All 1/0awg OFC SounDigital EVO 5K amp, Two 15" Fi SSD subs Next Level Fabrication @ 7 cubes net, tuned to 32HZ
560ti Posted July 16, 2020 Author Report Posted July 16, 2020 Thanks for the 2 post above. I forgot to mention that my stock alternator is only 90amps so that's why I was eyeing something higher. Getting an AGM battery for my car is majority of the cost of just getting a higher tier alternator so that's why I was leaning more towards that option
1point21gigawatts Posted July 17, 2020 Report Posted July 17, 2020 22 hours ago, Backwoods said: So much is dependent on the vehicle you have and the electrical draw for its stock components and the stock alternator size... I personally feel like anything over 1500rms should have upgraded electrical... But a 200amp alternator and adding 50-75AH to what came stock would be plenty... OK, so first things first... Lets start with if you had no system at all... A stock lead acid battery is designed for cranking amps, and normally doesnt have a very large reserve, and amp hours are relatively low. An alternator runs the vehicle while its on, the battery cranks the vehicle, the alternator is only designed to run the electrical components and recharge the minimal drainage caused by cranking the car, not charging fully drained batteries. Charging drained batteries puts added stress on an alternator and can make them fail prematurely. Now lets add in the system... And factor in a bit of the stock electrical draw... Lets say your stock alt is 80 amps, your car needs 60 when the AC is running, using power windows and headlights are on... Lets say the reserve capacity on the battery is 65ah, not unusual.... Now you have 1500rms drawing 150 amps... Do the math... 150 for the amp +60 for the car =210... stock 80amp alternator + 65 AH from stock battery = 145... Now your stock battery is draining and the stock alternator is required to work even harder, straining it and causing wear that could be prevented by upgrading electrical... All that being said, you wont be pulling 1500 watts after rise, its rare you will be using the full draw for stock electrical components, and you could likely get by just fine without upgrading, but i still feel its best to upgrade with anything over 1500. In auto tech and performance college we were taught one of the main reasons alternators fail is from being in charge mode too often, for too long.... PLUS, upgrading will help your amp get the 14.4 volts while playing, which will give you closer to their rated power than running them at 12-13 volts. A 1500 watt amp doesn’t draw 150 amps of current on music. The current readings are read on sinusoidal signals, not music. Music consumption is about half the amperage. Then you have to factor in impedance rise which pulls less current because it’s generating less rms. That 1500 watt rms amp would generate about half that rms after impedance rise and voltage drop and then since it’s music current then that figure is cut in half again. So 800 rms on a sine wave is pulling about 80 amps of current. But 800 rms on music is pulling about half that amount of current which is 40 amps of average current. Average. Because at frequencies where there is t much impedance rise that 1500 rms amp would be doing about 1200 rms on some frequencies and on music that draw would be about 60 amps of current. He doesn’t need a high output alternator on that minimal rms and current draw. A big 3 upgrade and an extra agm battery would be more than enough. And if he wants higher voltage from his alternator then he can add a 1n4004 diode to the sense wire on his stock alternator. “How can we help you?” “And don’t forget to tell them that the customer isn’t always right.”
1point21gigawatts Posted July 17, 2020 Report Posted July 17, 2020 Get a 120ah agm battery and do a big 3 under your hood. That’s it. And if you want higher voltage then watch this video. The sense wire is the wire that reads constant voltage even when the vehicle is off. To check to find out which one it is use a digital multimeter. “How can we help you?” “And don’t forget to tell them that the customer isn’t always right.”
1point21gigawatts Posted July 17, 2020 Report Posted July 17, 2020 The only smart decision that includes a high output alternator in this scenario is if you ever plan on using a bigger amp than 1500 rms on a future upgrade. “How can we help you?” “And don’t forget to tell them that the customer isn’t always right.”
560ti Posted July 17, 2020 Author Report Posted July 17, 2020 My last setup (2015 to 2018) was similiar power usage and the stock alternator was a huge bottleneck. Even with the biggest XS brand AGM battery I could fit + big 3 I saw signficant voltage drop even with the amp at half tilt. The moment I upgraded to a Singer alt my output more than doubled and my voltage never dipped below 14V. I don't mind upgrading the alternator, to be honest it's not much more expensive then buying a Northstar/X2/XS AGM battery anyways
Backwoods Posted July 17, 2020 Report Posted July 17, 2020 Yeah its not necessarily a necessity at 1500rms for sure.... but thats just my opinion of what id do... There are several videos and threads out there from lots of big name audio people that say something pretty similar stating anything over 1500 rms should have upgraded electrical... Some say anything over 1000rms.. Some say 2K.... Most say to start with big 3, then more tend to say to upgrade the alternator before batteries, but opinions vary. I watched quite a few of these videos when determining whether or not i wanted to get an amp bigger than 1K... But there are plenty of people running 3K amps on 4 gauge wire with stock batteries and stock alternators too. How long there battery and alternator will last is anyones guess. And the possibility that they are getting anywhere near the 14.4 volts that their amp does rated power at is slim to none while music is playing. Voltage drop without upgraded electrical is a bigger concern, and you already lose a lot of power to the subs due to rise, which you cant do anything about... But you can do something to prevent the loss of power due to decreased voltage. Some google searches, "car audio when to upgrade alternator" "Alternator or battery" "when to upgrade electrical for car audio" Will lead to TONS of good reference materials by plenty of people who have been competing and installing car audio for many years. I never go by just one source for anything so i suggest people do plenty of research and come to their own conclusion for their personal situation. There is a huge difference between running a cheap over rated 1500rms amp for 10-15 minutes a day playing country music VS running an under rated 1500rms amp for a few hours a day playing bass boosted music and doing demos with sine waves every chance you get. Singer 250amp Alt, Singer PCM bypass harness Titan8 Lithium Underhood safe BCI PWR-S5 Big 3 W/ dual runs of power/ground. All 1/0awg OFC SounDigital EVO 5K amp, Two 15" Fi SSD subs Next Level Fabrication @ 7 cubes net, tuned to 32HZ
1point21gigawatts Posted July 17, 2020 Report Posted July 17, 2020 34 minutes ago, 560ti said: My last setup (2015 to 2018) was similiar power usage and the stock alternator was a huge bottleneck. Even with the biggest XS brand AGM battery I could fit + big 3 I saw signficant voltage drop even with the amp at half tilt. The moment I upgraded to a Singer alt my output more than doubled and my voltage never dipped below 14V. I don't mind upgrading the alternator, to be honest it's not much more expensive then buying a Northstar/X2/XS AGM battery anyways That agm must of not had that many amp hours or that factory alternator was malfunctioning and/or the rear battery’s ground could of been too long and needed more current (bigger alternator) to stay up. Something was wrong. For sure. I’ve had 1500 rms systems before, even on stock electrical. Before my homeboy upgraded he had on a stock 130 amp alternator with a big 4 upgrade on a regular battery and a shuriken 140ah agm in the rear on a Rockford t1500bdcp (probably draws more current than any 1500 watt amp out right now. A lot of current in reference to the rms. Rockford bdcp amps are known for that. I had one too, so I know.) on a 19” Rockford t3 subwoofer. Cold voltage of 14.4v and Never dropped below 14v even on the hardest pulls. This was at idle. There was something wrong with that factory alternator on that vehicle you are speaking of or that agm battery didn’t have enough amp hours. But upgrading an alternator never hurts and always helps. It’s about the same price as a good battery and it’s more important than a good battery. So I don’t object to getting a high output alternator. One more thing, what kind of amp and what kind of agm? “How can we help you?” “And don’t forget to tell them that the customer isn’t always right.”
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