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Hello. I have a 2005 Ram 1500 SLT HEMI. It wouldn't start this morning(wouldn't turn over, solenoid just chattered) It was very cold here -35C, -45C with windchill. The battery was frozen. I put a new battery in and it started and i let it run for about 20min. I put a voltmeter on the battery and i had a couple concerns;
#1 voltage was fluctuating sometimes, 12V to 15.2V this only happened a couple of times for a short period. the rest of the time it was pretty steady around 15V
#2 15V seems high to me, i thought the voltage regulator should limit the voltage to about 14.2V(maybe the newer vehicles are different)
I do suspect the voltage regulator and alternator. My question is "Where is the voltage regulator?" is it built in to the alternator? is it external? can i purchase just the regulator or get a rebuild kit with brushes and regulator in it? If the regulator is external I would buy one and install it. If that fixes the problem, i am happy. If not i will take the alternator off and get it tested.
Any input would be great. Thanks for your time.
 

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hey man i would definately pull the alt of and get it tested cant hurt and it's free and just takes a little time....... but you are defiantely correct 15v is to high....ill try to see if i cant find out about the rest but my first guys would be the alternator and dont forget the battery is kinda of a regulator it soaks up the spikes and lets power through on dips in power when the trucks running but the alt charges but also takes care of the bulk of the power to the truck while it's on......... now you can do a redneck alternator test to see if it's bad this isn't 100% but while the trucks running if you pull the positive wire off the battery if the truck shuts off then you know the alt is bad.
 

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now you can do a redneck alternator test to see if it's bad this isn't 100% but while the trucks running if you pull the positive wire off the battery if the truck shuts off then you know the alt is bad.

Do NOT try this. It's a good way to fry modules in your truck. The alternator isn't likely to be the problem. The charging rate is PCM controlled and the battery temp sensor is one of the main inputs for determining the charging rate. You need to find out if the PCM is seeing the correct temp from the sensor.
 

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Do NOT try this. It's a good way to fry modules in your truck. The alternator isn't likely to be the problem. The charging rate is PCM controlled and the battery temp sensor is one of the main inputs for determining the charging rate. You need to find out if the PCM is seeing the correct temp from the sensor.
I have did this before Never no issues with frying anything. But I could be wrong with newer vehicles.
 

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yes you could fry something but.... but most likely blow a few fuses out befor any damage could be done..... it just a simple check if you dont want to pull the alt off..... but yes again not necessarily safe or 100%
 

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yes you could fry something but.... but most likely blow a few fuses out befor any damage could be done..... it just a simple check if you dont want to pull the alt off..... but yes again not necessarily safe or 100%
May I ask your qualifications to be handing out advice on Chrysler charging systems?
 

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well i have owned 3 dodge rams and i spent 3 1/2 years working as a mechanic until i got laid off and i do side mechanic work and have always worked on my own vehicles.im not ASE certified but i am knowledgeable..... but i will also be the first one to admit i always have more to learn.
 

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hey man i would definately pull the alt of and get it tested cant hurt and it's free and just takes a little time....... but you are defiantely correct 15v is to high....ill try to see if i cant find out about the rest but my first guys would be the alternator and dont forget the battery is kinda of a regulator it soaks up the spikes and lets power through on dips in power when the trucks running but the alt charges but also takes care of the bulk of the power to the truck while it's on......... now you can do a redneck alternator test to see if it's bad this isn't 100% but while the trucks running if you pull the positive wire off the battery if the truck shuts off then you know the alt is bad.
That works if the alt is not charging at all, but you can pretty much tell that with a voltmeter. He's got high voltage, not sure I'd want to put that through my electronics.
 

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Discussion Starter #9
Do NOT try this. It's a good way to fry modules in your truck. The alternator isn't likely to be the problem. The charging rate is PCM controlled and the battery temp sensor is one of the main inputs for determining the charging rate. You need to find out if the PCM is seeing the correct temp from the sensor.
Thanks to all that replied. RamTech how do I go about finding out if the PCM is seeing the correct temp from the sensor? I am not doubting your advice but could you explain a little more about the battery temperature sensor(location, where i would check the input to pcm) and why they use this as an imput for the charging system. If the battery is too hot or too cold do they adjust the voltage? Sorry but i am used to the older vehicles that didn't have computers. The last time i checked voltage at battery with truck running I had 14.9Volts. Do you know the voltage range the pcm regulates the voltage at? Thanks for your time. :)
 
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