when im in my car with the headlights on and the radio and i put up my windows all my lights in the car dim. i just replaced my alternator like two months ago, anybody got any ideas on why this would happen
Hmmmm..your lights go dim because something is chewing up your voltage.
Solutions
1.) Battery voltage is low and you need to replace the battery.
2.) If you have a sound sytem running (a high wattage one 400 or more) then you should get another battery or get a capactior.
3.) Your alternator could possibly(but most unlikely) be damaged.
__________________
Electrical Engineer in da his house.
"If you eliminate the impossible then whatever left, however improbable must be the truth!"
Huh??? Free battery testing??? Just attach a voltmeter across the top of the battery and see if its reading 12Volts...If its less than 12 then the battery needs replacing...If its higher than 12 then its not the battery!!
__________________
Electrical Engineer in da his house.
"If you eliminate the impossible then whatever left, however improbable must be the truth!"
hook up the voltmeter, make sure you have at least 12 volts, crank the car and see if the voltage drops below 9.6volts, if it does, battery is getting weak, then when running see how much the battery has, because that is how much the alternator is charging, or trying to meet, this is just basically monitoring the battery voltage at different conditions, even check out how much it drops when things get dim....when you play with the accessories....
Originally posted by UNISH25 Huh??? Free battery testing??? Just attach a voltmeter across the top of the battery and see if its reading 12Volts...If its less than 12 then the battery needs replacing...If its higher than 12 then its not the battery!!
no your wrong...
just because a battery test 12 volts doesnt mean that the battery pushing out enough amps to crank over properly... now yes if the battery test like 10.5 volts there is something wrong with the battery
just because a 9 volt battery tests 9 volts doesnt mean its going to work
I have a red top, same thing for me, same in my mom's maxima. Headlights on, and when I roll up my windows, the headlights dim a bit. There's nothing wrong. Window motors eat up some power.
just because a battery test 12 volts doesnt mean that the battery pushing out enough amps to crank over properly... now yes if the battery test like 10.5 volts there is something wrong with the battery
just because a 9 volt battery tests 9 volts doesnt mean its going to work
Hey man, thats it!!! Ima have to get more technical on all you peeps that keep hatin on my shiz.
I guess 4 years of engineering school wasn't worth it! LOL!!
Iiight...Listen up....NO I'm not wrong(sorry for the rudeness, but its true)!!!
If a battery is testing 12 volts....
Lets see...according to ohms law...V=IR. V=voltage, I=current, R=resistance.
Lets assume Resistance is the same all the time, therefore its constant in your car... The equation reduces down to 12=I*R. So I is dependant on V. If the battery tests 12 volts, then yes! It can pump out the required current! Assuming R does not change! It has to be able too! Ohms law prooves that!
Now when we start the car, we use 12 volts, the 12 volts go through inductor coils...when it goes through the coils, the voltage shoots straight up!!! Giving us the spark within the plugs.
Now...suppose you use a 9v cheap radioshack battery(those little square ones...) with a two 1.5volts batteries in series. Thats 12 volts! In theory, this is just as good as the 12volt car battery.
Thus, in theory this will absolutely work!!! IN THEORY!!!**IN THEORY!!!!!!!! 12=I*R. The 12volts in the battery would be converted through the coils, and give the high voltage needed to start the car.
In reality...You'll most likely blow the shiz up outta those little batteries. That batteries would only be able to withstand a certain amount of current before it heats up and literally blows up!!(SO DO NOT EVEN THINK OF TRYING IT, UNLESS YOU WANT CORROSIVE ACID ALL OVER YOUR FACE!!)
Your car battery is big because it can pump out more current. About 300-600 cold cranking amps depending on the battery! If your battery is reading 12 volts, then it will give you the power required to start your car!!! It has to!!!!!!!! This is proven by Ohms law!!! The electrons will be come outta that battery easily!
If the battery is 11/12 volts or less...then it might not! The voltage will be converted but not enough to spark the plugs.
Less electrons will come out! If it is more than 12 or 15 volts it will work, but it might blow up something in your car. Like alarm systems and radio! Because of the high voltage
Now suppose your voltage is 12 volts and your cars not starting. This means only a couple of things!
The only case I can think of is if the resistance in your battery is increased...
V=I*R.
V/R=I
As you can see from Ohms law if you increase the resistance the current gets lowered. If the resistance of your battery gets increased, then the amount of current your battery can supply will get lowered.
How can this happen you ask?
If your battery is hot, then its resistance is probably higher. Therefore the current you are getting is lowered. And your battery might not supply the required current needed to start the car.
Also if you apply multiple loads, while starting the car then it will fairl. IE Speaker systems, power windows, headlights, these all apply a load across the battery! Thus making the required voltage to start the car lower than needed!!!!
So if your battery is 12volts, I can assure you 100% that your battery will be able to supply the current needed to start your car! Ohms law states it!
PHEW! SORRY FOR THE INDEPTH STUFF, BUT PEOPLE BE HATIN!
__________________
Electrical Engineer in da his house.
"If you eliminate the impossible then whatever left, however improbable must be the truth!"
Last edited by UNISH25 : May 11th, 2003 at 05:15 PM.
Originally posted by 1997 GA16DE I have a red top, same thing for me, same in my mom's maxima. Headlights on, and when I roll up my windows, the headlights dim a bit. There's nothing wrong. Window motors eat up some power.
The headlights dim when you roll up your window, because you apply a "load" across the battery.
If you apply multiple loads across a single battery then the voltage across the battery will decrease!
__________________
Electrical Engineer in da his house.
"If you eliminate the impossible then whatever left, however improbable must be the truth!"
Originally posted by nismoracr when im in my car with the headlights on and the radio and i put up my windows all my lights in the car dim. i just replaced my alternator like two months ago, anybody got any ideas on why this would happen
By the way, the alternator does not supply current unless the engine is running. The only function of the alternator is to supply current to the car when the engine is running and to recharge the battery!
__________________
Electrical Engineer in da his house.
"If you eliminate the impossible then whatever left, however improbable must be the truth!"
Originally posted by UNISH25 The headlights dim when you roll up your window, because you apply a "load" across the battery.
If you apply multiple loads across a single battery then the voltage across the battery will decrease!
Well, that's pretty much what I'm saying, it's completely normal. It's just like trying to accelerate with the AC on. Just like the battery, the AC puts extra work on the engine and the engine can't propel the car as easily.
Just to make that technical part clearer, each electronic accessory takes a certain ammount of current (Amps). Window motors take a good amount of current (especially when you roll 4 up at once like me). I could be wrong on a few of these upcoming numbers, but a typical car battery can support a temporary amount of 600-800 cold cranking amps. But normally, you will not ever need anymore than 100Amps (unless you have an electrical problem). The starter pulls about 75A and the headlights pull about 4.5A per bulb). A typical AA battery can only support maybe 2 amps max. I have a digital camera, I'm not sure what it draws from the batteries, but when I take out the batteries, they are litterally too hot for me to hold on to. If you overload the battery, it cannot move the electrons fast enough and the cells (usually a paste) will heat up and eventually explode.
Originally posted by UNISH25 Hey man, thats it!!! Ima have to get more technical on all you peeps that keep hatin on my shiz.
I guess 4 years of engineering school wasn't worth it! LOL!!
Iiight...Listen up....NO I'm not wrong(sorry for the rudeness, but its true)!!!
If a battery is testing 12 volts....
Lets see...according to ohms law...V=IR. V=voltage, I=current, R=resistance.
Lets assume Resistance is the same all the time, therefore its constant in your car... The equation reduces down to 12=I*R. So I is dependant on V. If the battery tests 12 volts, then yes! It can pump out the required current! Assuming R does not change! It has to be able too! Ohms law prooves that!
Now when we start the car, we use 12 volts, the 12 volts go through inductor coils...when it goes through the coils, the voltage shoots straight up!!! Giving us the spark within the plugs.
Now...suppose you use a 9v cheap radioshack battery(those little square ones...) with a two 1.5volts batteries in series. Thats 12 volts! In theory, this is just as good as the 12volt car battery.
Thus, in theory this will absolutely work!!! IN THEORY!!!**IN THEORY!!!!!!!! 12=I*R. The 12volts in the battery would be converted through the coils, and give the high voltage needed to start the car.
In reality...You'll most likely blow the shiz up outta those little batteries. That batteries would only be able to withstand a certain amount of current before it heats up and literally blows up!!(SO DO NOT EVEN THINK OF TRYING IT, UNLESS YOU WANT CORROSIVE ACID ALL OVER YOUR FACE!!)
Your car battery is big because it can pump out more current. About 300-600 cold cranking amps depending on the battery! If your battery is reading 12 volts, then it will give you the power required to start your car!!! It has to!!!!!!!! This is proven by Ohms law!!! The electrons will be come outta that battery easily!
If the battery is 11/12 volts or less...then it might not! The voltage will be converted but not enough to spark the plugs.
Less electrons will come out! If it is more than 12 or 15 volts it will work, but it might blow up something in your car. Like alarm systems and radio! Because of the high voltage
Now suppose your voltage is 12 volts and your cars not starting. This means only a couple of things!
The only case I can think of is if the resistance in your battery is increased...
V=I*R.
V/R=I
As you can see from Ohms law if you increase the resistance the current gets lowered. If the resistance of your battery gets increased, then the amount of current your battery can supply will get lowered.
How can this happen you ask?
If your battery is hot, then its resistance is probably higher. Therefore the current you are getting is lowered. And your battery might not supply the required current needed to start the car.
Also if you apply multiple loads, while starting the car then it will fairl. IE Speaker systems, power windows, headlights, these all apply a load across the battery! Thus making the required voltage to start the car lower than needed!!!!
So if your battery is 12volts, I can assure you 100% that your battery will be able to supply the current needed to start your car! Ohms law states it!
PHEW! SORRY FOR THE INDEPTH STUFF, BUT PEOPLE BE HATIN!
i would reply to that but i didnt want to read the whole thing
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