Electrical system help

[Bumpin' Goalie 10+ year member]

Voltage and current stay proportionate. When the amp draws heavy current and the wire cannot carry it, the wire acts like a resistor in series. It drops some voltage. This in turn limits the amount of current the amplifier can draw.

^^this is what i was trying to convey.

Sorry for anything you found to be false or untrue, unfortunately i only know what i am taught by others, and know from my limited electrical experience.

Glad that i am continuing to learn, and will be more cautious as to who i will take information from in the future; and am/will continue to educate myself in a hands on environment.

And in response to Bubba: I understand your views, yet, please be more specific with your insults. In fact, i am quite knowledgeable in most fields of car audio and its pertaining elements. I am a relative novice to electrical work, however i am far from a beginner in other aspects.

Once again, sorry, thank you.

 

[Cap'n Andy 10+ year member]

^^this is what i was trying to convey.
Sorry for anything you found to be false or untrue' date=' unfortunately i only know what i am taught by others, and know from my limited electrical experience.

Glad that i am continuing to learn, and will be more cautious as to who i will take information from in the future; and am/will continue to educate myself in a hands on environment.

And in response to Bubba: I understand your views, yet, please be more specific with your insults. In fact, i am quite knowledgeable in most fields of car audio and its pertaining elements. I am a relative novice to electrical work, however i am far from a beginner in other aspects.

Once again, sorry, thank you.[/quote']

Pick up a decent book about electronics and electricity.

 

[bubbagumper6 5,000+ posts]

Basic Car Audio Electronics

nuff said

 

[darudeone 10+ year member]

Bumpin' Goalie, literally none of the things you have said so far are accurate. It's great that you're trying to figure them out for yourself, but until you have it right please do not post these things. They are misinforming people.
First, The battery is not the source. The alternator is the source. You can literally start your engine and then remove the battery. How do you think jump starting works? Current flows from the highest source of potential ONLY. The alternator charges at ~14. The battery never charges higher than around 13v and only puts out minimal current above 12.6v. While the vehicle is on and the voltage is above 12.6v ALL CURRENT IS DRAWN FROM THE ALTERNATOR because it is the highest source of potential.

Your hose and straw ******* analogy are something people can relate to. Unfortunately that is not how it works.

Voltage and current stay proportionate. When the amp draws heavy current and the wire cannot carry it, the wire acts like a resistor in series. It drops some voltage. This in turn limits the amount of current the amplifier can draw. If enough current is drawn through the wire to get the wire really hot, the wire will melt the insulation and start a fire.

Voltage is also knows as Electro-Motive Force or EMF. This means that it is the only force pushing or ******* the current through the pipes. We know that using a smaller conductor does not raise the voltage. This disproves your analogies.

Noob question: If "ALL CURRENT IS DRAWN FROM THE ALTERNATOR..." , why do we run a power line to the battery?

 

[ahole-ic]

Noob question: If "ALL CURRENT IS DRAWN FROM THE ALTERNATOR..." , why do we run a power line to the battery?

In a parallel circuit it shouldn't matter where you connect the power wire. Connect it directly to the alternator. You won't have any problem. If you were to do this and dc clamp the wire/s between your battery and alternator, you'd see that the only current passing between the battery and alternator are the few amps the battery is drawing to charge.

Here is a noob question for you. How does current flow? Does it flow between two sources if the voltage is identical? Is it possible to hook a +12v positive with a +5v ground? If so, what would be the effective system voltage?

 

[darudeone 10+ year member]

bro, Id gotta bust out the science book on that. way over my head. Still got 3 weeks before My meesly 780rms total set up

 

[ahole-ic]

bro, Id gotta bust out the science book on that. way over my head. Still got 3 weeks before My meesly 780rms total set up

Then just trust me. Current only flows from the highest source of potential. This is why your alternator puts out a voltage of ~14 to your 12v battery. It's so current will flow FROM the alternator TO the battery keeping it charged. The battery is ONLY in the vehicle to start the car. That's IT. It will also prevent the voltage from going below 12v on heavy bass notes where the alternator cannot keep up, but the voltage has to get down to its resting voltage before it discharges any significant amount of current.

 

[darudeone 10+ year member]

I was just curious, but not that much technically. I am going to do the big 3 and fuse the line to the alt. I got an x-cab toyota with a (will double check) 70A alt. I think I need a 80A fuse. I got 2 gage welding wire for the big 3 and power to a fused distrobution block, it splits to 4gage for MBQ4125 2 sets of polk db 100rms comps and 6 gage to an eclipse ea4200 (140 rms bridged) for 2 12" rf's @ 150rms. First time doing this. I hope the subs are enough. I may upgrade later.

 

[Bumpin' Goalie 10+ year member]

Hi, i'm back lol.

So if i gather correctly, the main battery is only there for starting purposes. If this is true, why do ppl recommend a larger battery to help with voltage w/ the car on? Also, another question, (please correct me if i'm wrong) a battery in the back, run in-line, will be charged by the alternator, obviously. And the amps will draw power from it until it is depleted; which should only happen if the alternator cannot keep it charging as fast as the amps drain it; correct?

(metaphors seem to help me explain my questions)

In this sense, the alternator creates water to fill the batteries (lakes) which are being drained via wires (rivers) for power to the amps which draw current. If there is a shortage of water, the lakes will dry up and the thus the amps have no more water to receive.

This makes me think that the batteries are a stepping stone in between amp draw and the alternator.

This is what i seem to hear from most everyone. Because will not an amp wired from the battery, use it as a source of power b4 drawing straight from the alternator?

It has been my common belief that the alt's job is to make sure the battery sustains enough charge to power the electronics being used.

...Now; please educate me if you don't mind //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[bubbagumper6 5,000+ posts]

Hi' date=' i'm back lol.
So if i gather correctly, the main battery is only there for starting purposes. If this is true, why do ppl recommend a larger battery to help with voltage w/ the car on? Also, another question, (please correct me if i'm wrong) a battery in the back, run in-line, will be charged by the alternator, obviously. And the amps will draw power from it until it is depleted; which should only happen if the alternator cannot keep it charging as fast as the amps drain it; correct?

(metaphors seem to help me explain my questions)

In this sense, the alternator creates water to fill the batteries (lakes) which are being drained via wires (rivers) for power to the amps which draw current. If there is a shortage of water, the lakes will dry up and the thus the amps have no more water to receive.

This makes me think that the batteries are a stepping stone in between amp draw and the alternator.

This is what i seem to hear from most everyone. Because will not an amp wired from the battery, use it as a source of power b4 drawing straight from the alternator?

It has been my common belief that the alt's job is to make sure the battery sustains enough charge to power the electronics being used.

...Now; please educate me if you don't mind //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif[/quote']

Your analogy is close. If the current draw doesn't exceed what the alternator can output (instantaneously) then the alternator can supply all of the power for the amplifier and the battery will effectively do nothing. However the real world scenario is that alternators can't go from 0A to 200A instantly (it's just not possible), so when your heavy bass note hits, it will immediately pull down the system voltage. This is where the batteries come in. If the voltage is at 14v the batteries will be supplying nothing. But when the voltage drops to their resting point, which is 12v, sometimes closer to 13v, the batteries can supply huge amounts of current. So they almost act like a buffer for the alternator. But the alt is still the main source of power in the car, because while the batteries can supply huge amounts of current, they can't do that for forever, so as soon as that voltage drops below the 14v the alternator is putting out, it's current output will significantly increase and charge the batteries back up (after a slight delay of course). I hope that made sense and I hope I didn't miss anything...it's still early and I'm only half way through my coffee //content.invisioncic.com/y282845/emoticons/crap.gif.7f4dd41e3e9b23fbd170a1ee6f65cecc.gif

 

[stormsearch]

What bub is saying is all true. I will add a couple notes. Putting in a larger battery will only help if the alternator cannot keep up with the system voltage that the amps are continuously pulling for a set timeframe. BUT, after a short period of time, the larger battery will be no better than the one replaced since it has output enough current to drop it's capacity. A bigger battery will help in longer run times while the engine is off. A bigger battery will help to start vehicles that struggle particularly in colder climates (assuming a weak battery to begin with). Battery acts like a capacitor in the system to absorb voltage spikes (either from vehicle electronics or sound system) - a larger battery will not really help here.

Running your power wire to the alternator B+ stud is actually not a bad idea - since you would bypass the alt B+ to battery B+ cable run. But that will work the opposite way if the engine is off. However, powering away from the battery reduces its affect to help deal with the amp power spikes (it needs to overcome the added impedance of the wire from batt to alt vs. dealing with a power spike directly at the batt b+). Hence reason people like to add a 2nd battery in the rear near their amps. The alternator is a noisy machine (electromagnetic noise) so keeping power wires from it is preferred.

Also note, that the alternator operates to control voltage near the battery B+ terminal. There is a feedback wire that likely terminates near the batt b+ (fuse box or other power distribution type box). This ensures proper battery voltage based on temperature and provides longer battery longevity. Batteries have an optimal charge voltage dependent on temperature. Pulling power at the alt b+ will obviously provide a higher operating voltage to compensate for the voltage drop across the batt to alt wire.

Resting voltage of a battery is 12.7v (12.6v if you consider some of non-wet cell batteries), 100% SOC. If the resting voltage of the battery is at 12.5v, it is around 50% SOC. At 12.0v, battery is considered dead. This only relates to when a battery is not receiving or providing any current (resting voltage). Battery voltage will drop significantly during high power loads like starting your vehicle. Dropping to 8v is not uncommon for the very short period of time.

 

[Bumpin' Goalie 10+ year member]

Yes i understood. The Alt supplies power as much as it can directly. The battery compensates for the difference when needed. So because my amp voltage hovers between 13-13.7 depending on headlights, fans, etc, should i be concerned with my alt killing itself to keep up? especially @ night when it drops to ~13 with so many other car accessories to also power?

Thanks for the info, enjoy the rest of your coffee while i go make breakfast. Sleeping in late ftw //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[bubbagumper6 5,000+ posts]

Yes i understood. The Alt supplies power as much as it can directly. The battery compensates for the difference when needed. So because my amp voltage hovers between 13-13.7 depending on headlights' date=' fans, etc, should i be concerned with my alt killing itself to keep up? especially @ night when it drops to ~13 with so many other car accessories to also power?
Thanks for the info, enjoy the rest of your coffee while i go make breakfast. Sleeping in late ftw //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif[/quote']

It sort of depends...it's hard to tell how hard your being on the alternator. I ran my first system which was ~ 1600wrms off a stock 110A alt w/ a single yellowtop up front and had some bad dimming. I thought it would be fine to run until I can upgrade my alt. And it did seem to be ok, but when I did upgrade my alt, I opened up my stock alt and the **** thing was just charred. I mean I have no way to know for sure, but I'd guess that thing would have died in another month or so. Putting a lot of stress on the alternator can cause damage to it, and can cause it to fail. Whether or not your doing a lot of damage or not is hard to tell...

And enjoy your sleeping in. I'll take my 8-5, monday - friday, 17$ an hour work, any day //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[Bumpin' Goalie 10+ year member]

haha yea...I have training (hockey) ~4 hours a day. and Games whenever they're scheduled. So a bunch of traveling throughout the US and Canada, usually on a 2-5 games a week basis. But when i'm home. i have all but 4 hours a day to obsess over my car. No wonder i can't hold onto any of my money.

I'm not getting any dimming, etc, but i have not driven it for an extended period of time to where the battery was depleted. So i'm not sure. I suppose now would be the time to look into H/O alt's just in case. Don't want to get stuck somewhere.

 

[bubbagumper6 5,000+ posts]

haha yea...I have training (hockey) ~4 hours a day. and Games whenever they're scheduled. So a bunch of traveling throughout the US and Canada' date=' usually on a 2-5 games a week basis. But when i'm home. i have all but 4 hours a day to obsess over my car. No wonder i can't hold onto any of my money. I'm not getting any dimming, etc, but i have not driven it for an extended period of time to where the battery was depleted. So i'm not sure. I suppose now would be the time to look into H/O alt's just in case. Don't want to get stuck somewhere.[/quote']

lol, this thread isn't even about you...but anyway, it's not exactly easy to "look into your alt". I had to basically destroy mine (we destroyed it trying to get the stock pulley off). And you really shouldn't ever drive your batteries to depletion, it's not good for them.