Anybody Run Power Off Back of Alt.
08-19-2006, 04:24 PM
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Anybody Run Power Off Back of Alt. I was wondering if anyone here runs there power cable for there stereo off the back off the alternator. Granted I dont have a stereo and dont plan on ever having a real outragous stereo system but I thought it was benefit some of you guys on here that do. If you think about it it makes sense, you're always going to have power there just like if you were to run it off your battery, your going to have better sound because your going to have a good 12.6-13v there at all times while vehicle is running. Its going to save your bettery considerably by not putting the load and causing it to be cycled and continously charged and discharged whenever your amp hits. It sounds like a really good idea to me and is what I would do if ever decided to install any kind of aftermarket amp in my car. Granted I know it may be a little more of a PITA to run it off your alternator but for the few minutes it would take to jack it up and install and extra cable it would be worth it and save your battery some. I know it my put a little more stress on your alternator but if you have a decent alternator or even a HO one it should be fine. So whether or not this means anything to you guys or you think its a totally bad idea I thought I would post it up anyways.
Later Ben
Later Ben
08-19-2006, 05:16 PM
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since your alternator and battery are wired in parallel, you would get no benefit. The voltage at the alternator terminal and at the battery terminal will be very close. In fact, the power for the rest of the cars electronics originate at the battery, not at the alternator.
08-19-2006, 06:11 PM
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Yeah I know the voltage at the battery is going to be about the same as at the alternator. The whole point is to keep the amp from pulling from the battery then the alternator having to charge the battery back up since the amp is drawing directly from the battery. Its meant to help out your battery. The main reason batteries fail is from sulfated plates from being charged and discharged and if you have a amp pulling 30-40 amps from your battery all the time its going to shorten the life of the battery significantly. Most of the electronics are going to originate at the battery since its the heart of the system and everything is rated and designed for that system from the factory, not for an additional 500 or 800w amp. But I have never done this myself so I might be totally wrong it just made pefect sense to me when a Technician/Instructor told me about it.
Ben
Ben
08-19-2006, 10:18 PM
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The only time the amp would draw power is when the radio is turned on which turns on the amp, not when its hooked up the whole time its in the car. If thats what your talking about.
08-20-2006, 12:56 AM
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No No I know how a stereo works, I have hooked a few up in the past and have always wired the power cable to the battery. But when I heard about this I thought it was a good idea.
08-20-2006, 02:22 PM
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but your not drawing current from the battery.
When you have multiple power sources in the car, the load will come from the one with the highest voltage.
A car battery is about 12 volts. An alternator should output about 14 volts (usually closer to 13.5 or so in the real world).
So when the car is running, the alternator is the highest voltage source, so your alternator is powering the load of the car, including any amps or aftermarket electronics. This is regardless of whether your amp is connected directly to the battery or anywhere else in the car, since all of the wiring is in parallel.
Now, lets say you have a bass heavy song playing, and you want to jam out! You crank the system to 11 and rock out
. Now, if your system is of sufficient size, your amps current draw during big bass peaks may exceed your alternator capacity. When this happens, the voltage supplied by the alternator will drop, you may notice your head lights dimming as well. Once the alternator voltage becomes lower then 12.5 volts or so, the battery becomes the highest voltage source in the car, and powers the amps (and the rest of the car) until the excess current demand by the bass hit is over, and the amperage draw falls back down to a range the alternator can supply. Alternator voltage goes back up, and proceds to recharge the battery and power the car and system. All of this happens in a split second. If your system draws sufficient current to create this scenario often, it's time to invest in a bigger alternator.
This is how it all works, regardless of wether your amp is hooked to the battery, or to the alternator. The battery and alternator are connected in parallel by a 6 guage cable. So whatever is attached to one, is for all practicle purposes, connected to the other.
mike
When you have multiple power sources in the car, the load will come from the one with the highest voltage.
A car battery is about 12 volts. An alternator should output about 14 volts (usually closer to 13.5 or so in the real world).
So when the car is running, the alternator is the highest voltage source, so your alternator is powering the load of the car, including any amps or aftermarket electronics. This is regardless of whether your amp is connected directly to the battery or anywhere else in the car, since all of the wiring is in parallel.
Now, lets say you have a bass heavy song playing, and you want to jam out! You crank the system to 11 and rock out
. Now, if your system is of sufficient size, your amps current draw during big bass peaks may exceed your alternator capacity. When this happens, the voltage supplied by the alternator will drop, you may notice your head lights dimming as well. Once the alternator voltage becomes lower then 12.5 volts or so, the battery becomes the highest voltage source in the car, and powers the amps (and the rest of the car) until the excess current demand by the bass hit is over, and the amperage draw falls back down to a range the alternator can supply. Alternator voltage goes back up, and proceds to recharge the battery and power the car and system. All of this happens in a split second. If your system draws sufficient current to create this scenario often, it's time to invest in a bigger alternator.This is how it all works, regardless of wether your amp is hooked to the battery, or to the alternator. The battery and alternator are connected in parallel by a 6 guage cable. So whatever is attached to one, is for all practicle purposes, connected to the other.
mike
