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
no your wrong...UNISH25 said: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!!
ccroaddog said: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
The headlights dim when you roll up your window, because you apply a "load" across the battery.1997 GA16DE said: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.
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!nismoracr said: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
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.UNISH25 said: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!
UNISH25 said: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!
UNISH25 said: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!
LOL...sorry for the WHOLE electrical theory, just wanted you guys to know I wasn't an electrical idiot. AHHH...4 years of engineering school was probably worth it then..??? NAHHH!!! BSEEccroaddog said:i would reply to that but i didnt want to read the whole thing
isnt true though if a battery reads 12 volts doesnt mean its in full working order. And i will never question your knowledge again... if you would have answered first like you did the second time i would have just agreed. Anywho no hurt feeling :cheers:UNISH25 said:LOL...sorry for the WHOLE electrical theory, just wanted you guys to know I wasn't an electrical idiot. AHHH...4 years of engineering school was probably worth it then..??? NAHHH!!! BSEE
LOL...no offense taken man! We in good terms now. If a battery reads 12 volts...then you know everything is aok in it!ccroaddog said:isnt true though if a battery reads 12 volts doesnt mean its in full working order. And i will never question your knowledge again... if you would have answered first like you did the second time i would have just agreed. Anywho no hurt feeling :cheers:
maybe it was .7v shit like i said its been awile, lol or was that the voltage npn transistors turns on, hell its late and im getting tired lol. im a little rusty i was hoping unish25 could refresh my memory anyway.1997 GA16DE said:I've taken my battery all the way down to nothing before when I left my headlights on. Wouldn't that be 0 volts (well, maybe a small fraction)? My battery charged back up just fine.
It depends on the situation. You say you have a sound system.ccroaddog said:i should test my batt in my car that doesnt work now......hmmm since your a expert i would like you to answer this question.
Are caps worth it in car audio or is it better getting something different??
i think i might know your answer but humor me and the thread