does your RPMS drop when your idling?

[cappy72 10+ year member]

I just parked my car and I was finishing the rest of the song when I noticed that my engines rpms would noticeable decrease when the bass hit.... I dont have a high-out alternator...

does anyone else have this? or is this suppose to happen?

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[JimJ 5,000+ posts]

What size alt do you have, and what sort of current draw are you pulling from it...

It basically means your alt is having to work harder to keep the system voltage up.

 

[96pfinderSE 10+ year member]

i cant thinko of how to explain it but its like turnin on the A/C.

 

[JimJ 5,000+ posts]

i cant thinko of how to explain it but its like turnin on the A/C.

You're pulling current from a finite source, so the voltage drops according to Ohm's Law. The alt has to work harder to keep up with the voltage drop. An example would be if you ate nothing but McDonald's and KFC for a year, and expected your heart to keep up...it would have to work that much harder.

 

[cappy72 10+ year member]

I have an 110 amp alternator ...

Im using a D5 1200.1 amp and a Van Gogh 320.4 amp currently...

I also have a yellow top in the trunk...???? I would have thought that the yellow top would help a little...

 

[DJ CHAOTIC 666 10+ year member]

You're pulling current from a finite source, so the voltage drops according to Ohm's Law. The alt has to work harder to keep up with the voltage drop. An example would be if you ate nothing but McDonald's and KFC for a year, and expected your heart to keep up...it would have to work that much harder.

"SUPERSIZE ME"

 

[B_Master_Flash 10+ year member]

I have an 110 amp alternator ...
Im using a D5 1200.1 amp and a Van Gogh 320.4 amp currently...

I also have a yellow top in the trunk...???? I would have thought that the yellow top would help a little...

Very little. your battery only contributes once your alternator is tapped out anyway, doesn't matter how many batteries you have

 

[drkodin 10+ year member]

I have an 110 amp alternator ...
Im using a D5 1200.1 amp and a Van Gogh 320.4 amp currently...

I also have a yellow top in the trunk...???? I would have thought that the yellow top would help a little...

it would if it was charged. i'm willing to bet that you drained it enough so that the demand was larger than the supply. You may have that extra battery storage on a normal basis, but if you already used that extra capacity and then even tried to bump at idle you will get the exact result you encountered.

 

[drkodin 10+ year member]

Very little. your battery only contributes once your alternator is tapped out anyway, doesn't matter how many batteries you have

i would like to know why you think this, because it just doesn't make any sense, more batteries would drastically help in his situation.

however there is a drawback that most people misunderstand as something that needs to be avoided at all costs. A battery is a backbone to any electrical system, it works in conjunction with any electrical system and is fully designed to run on its own accord. Running a system off a battery alone or by relying on that battery to keep up the charge while the input voltage is low is by no means a bad thing.

The part that most people go the wrong way is they tell people that they will only end up killing an electrical system too soon by using multiple batteries off a stock alternator. If he is at idle, and he adds a second yellow top to his system, all his problems will go away including the possibility of problems like headlight dimming as long as he doesn't discharge more than he will EVENTUALLY charge. The alt will pick up the moment the car starts moving again and since music is dynamic it should also have more than enough current to start charging the batteries back up slowly.

ok, with that said i don't think that a second battery is necessarily the best solution to the problem. The best solution actually derives from my point on multiple batteries (proving that single or multiple the issue remeins the same) that he isn't allowing time for the battery to charge back. For a single yellow top on a 110a alt i would give at least 5min driving time load free (no music, heater, AC, winshield wipers, power windows, etc) to charge back up. 2 yellow tops i would want 10min driving time. This insures the charge is there not only to start the car but also to save your alternator.

The only thing that will kill an alt faster is if you drain the battery so far that the alt is the sole source of current.

 

[cappy72 10+ year member]

Ok I have 1 regular battery that is hooked up in the engine bay, I have a yellow top hooked up in the trunk. I installed the battery when it was fully charged. I dont normally sit around playing my music. I am normally on the go... although I have been making short trips to and from school, which is less than 1/2 mile away.

 

[Spkrman]

i would like to know why you think this, because it just doesn't make any sense, more batteries would drastically help in his situation.
however there is a drawback that most people misunderstand as something that needs to be avoided at all costs. A battery is a backbone to any electrical system, it works in conjunction with any electrical system and is fully designed to run on its own accord. Running a system off a battery alone or by relying on that battery to keep up the charge while the input voltage is low is by no means a bad thing.

The part that most people go the wrong way is they tell people that they will only end up killing an electrical system too soon by using multiple batteries off a stock alternator. If he is at idle, and he adds a second yellow top to his system, all his problems will go away including the possibility of problems like headlight dimming as long as he doesn't discharge more than he will EVENTUALLY charge. The alt will pick up the moment the car starts moving again and since music is dynamic it should also have more than enough current to start charging the batteries back up slowly.

ok, with that said i don't think that a second battery is necessarily the best solution to the problem. The best solution actually derives from my point on multiple batteries (proving that single or multiple the issue remeins the same) that he isn't allowing time for the battery to charge back. For a single yellow top on a 110a alt i would give at least 5min driving time load free (no music, heater, AC, winshield wipers, power windows, etc) to charge back up. 2 yellow tops i would want 10min driving time. This insures the charge is there not only to start the car but also to save your alternator.

The only thing that will kill an alt faster is if you drain the battery so far that the alt is the sole source of current.

well said

so long as you give time for the batteries to recharge... you can run whatever you want on the stock alt.

Good idea to let it sit in a charger overnight, keeps the batts in tip top shape anyway.

btw this "problem" isn't out of the ordinary

 

[B_Master_Flash 10+ year member]

i would like to know why you think this, because it just doesn't make any sense, more batteries would drastically help in his situation.
however there is a drawback that most people misunderstand as something that needs to be avoided at all costs. A battery is a backbone to any electrical system, it works in conjunction with any electrical system and is fully designed to run on its own accord. Running a system off a battery alone or by relying on that battery to keep up the charge while the input voltage is low is by no means a bad thing.

The part that most people go the wrong way is they tell people that they will only end up killing an electrical system too soon by using multiple batteries off a stock alternator. If he is at idle, and he adds a second yellow top to his system, all his problems will go away including the possibility of problems like headlight dimming as long as he doesn't discharge more than he will EVENTUALLY charge. The alt will pick up the moment the car starts moving again and since music is dynamic it should also have more than enough current to start charging the batteries back up slowly.

ok, with that said i don't think that a second battery is necessarily the best solution to the problem. The best solution actually derives from my point on multiple batteries (proving that single or multiple the issue remeins the same) that he isn't allowing time for the battery to charge back. For a single yellow top on a 110a alt i would give at least 5min driving time load free (no music, heater, AC, winshield wipers, power windows, etc) to charge back up. 2 yellow tops i would want 10min driving time. This insures the charge is there not only to start the car but also to save your alternator.

The only thing that will kill an alt faster is if you drain the battery so far that the alt is the sole source of current.

Ok, but you won't start drawing from the batteries until the voltage drops to below their level, which means your alt is being over worked. So no matter how many batteries you have, you still have to exhaust your alt before they even come into the picture.

PS I'm not stating this as fact, it's just what I thought, if I'm wrong pls correct me

 

[drkodin 10+ year member]

Ok, but you won't start drawing from the batteries until the voltage drops to below their level, which means your alt is being over worked. So no matter how many batteries you have, you still have to exhaust your alt before they even come into the picture.
PS I'm not stating this as fact, it's just what I thought, if I'm wrong pls correct me

yes you are correct, in a way.

Amps used to be rated at 12.5V for the very reason you made your statement, alternators just aren't going to be able to handle a large load like a stereo system. As ratings inflated they started being rated at 14.4V which is still legit in its own way.

The big key is that music is dynamic and unless you have a highly trained ear you will not notice the power drop from 14V to 12V, especially since the volume would be extreemly high anyway. Now if you judged an amp with a tone on an spl meter, the meter would certainly reflect the power gain.

back to one of those half truths. The statement is absolutely correct, but the meaning and direction behind it were lost.

 

[drkodin 10+ year member]

Ok I have 1 regular battery that is hooked up in the engine bay, I have a yellow top hooked up in the trunk. I installed the battery when it was fully charged. I dont normally sit around playing my music. I am normally on the go... although I have been making short trips to and from school, which is less than 1/2 mile away.

Unless you have a battery isolator you need to only run the yellow top. Without that isolator batteries need to be the same if there are multiple.

Have you always had the problem of rpms dipping or is it just since the short trips started? The problem we got on a tangent about is related to you in a way since the problem does come from a weak electrical system, now we just have to help you pin point it. I would suggest first to go drive around a while with everything turned off, at least 20min or so just to be sure, then play the stereo like you were before. Do the rpms still dip? Did it help at all and if so how long?

One last question, have you upgraded any of the car's wiring, like alternator or battery grounds and such?

 

[netherland24_ 10+ year member]

this topic really helped me out, i have one question though i just got 2 1200 mono concept amps and i dont know subs yeah but whatever, i have a die hard Gold battery, with a 130 stock alternator. in a ford windstar would it be able to take 2400 watts? all original wiring under the hood. thanks