Voltage Question .....
Thread Starter
aka allbottle¬hrottle
Joined: Jun 2007
Posts: 13,759
Likes: 0
From: Brooklyn New York The DVL and the chicken sleep with the fishes....
St. Jude Donor '08
Voltage Question .....
I posted this in the FI section as well , buy maybe you gentlemen have an idea .....
Hey folks - Im running the Procharger P1-SC , and Im noticing the my voltometer is getting lower as I drive ...
What I mean is , when I start the car in the AM (cold) Voltage is bettween 14.1-13.9 , once the car is fully warmed up it drops slightly to about 13.9-13.5 , however if Ive been driving her hard for about an hour the voltage starts to fluctuate and settles as low as 11.9 on the guage ...
This of course is at idle with the headlights or DRL's on with nothing else (heat , A/C , radio , ect...) , as soon as Im moving again voltage shoots right back up into the 13's
No warning on the DIC and she starts fine and all , but Im curious what could be causing this .
Any thoughs ???
Hey folks - Im running the Procharger P1-SC , and Im noticing the my voltometer is getting lower as I drive ...
What I mean is , when I start the car in the AM (cold) Voltage is bettween 14.1-13.9 , once the car is fully warmed up it drops slightly to about 13.9-13.5 , however if Ive been driving her hard for about an hour the voltage starts to fluctuate and settles as low as 11.9 on the guage ...
This of course is at idle with the headlights or DRL's on with nothing else (heat , A/C , radio , ect...) , as soon as Im moving again voltage shoots right back up into the 13's
No warning on the DIC and she starts fine and all , but Im curious what could be causing this .
Any thoughs ???
Advanced
Joined: Mar 2006
Posts: 67
Likes: 0
As you battery gets warmer (read hot) the internal resistance of the battery goes down, then the alternator does not have to output as much current, so voltage follows. What is your idle speed? I noticed a mod was mentioned. Did you put under speed pulleys on your accessory drives? The alternator will only output the correct voltage as long as it is spinning fast enough.
Thread Starter
aka allbottle¬hrottle
Joined: Jun 2007
Posts: 13,759
Likes: 0
From: Brooklyn New York The DVL and the chicken sleep with the fishes....
St. Jude Donor '08
I would be more inclined to think it was a heat issue as well , but the temps on the car are even lower than normal with it getting cold outside .... Would a belt loose tension as the day went on ? I would think it would be the opossite ...
Pro
Joined: Nov 2005
Posts: 672
Likes: 1
From: Sapulpa Oklahoma
Heat will also cause resistance in a loose connection. I'd check every ground and hot cable in the engine compartment. Especially the battery cables. Could be that one could be loose from the mods...........
Intermediate
Joined: Jun 2007
Posts: 43
Likes: 0
From: Mobile Alabama
can't say for sure but i would think it is a heat problem as well...not necissarily underhood temps or anything but rather the elctronics associated with the charging system...ie, rectifier ect.
Le Mans Master
Joined: Aug 2004
Posts: 5,259
Likes: 16
From: Monroe Township New Jersey
St. Jude Donor '05-'06-'07-'08-'09-'10-'11-'12-'13-'14-'15-'16
St. Jude donor in memory of jpee '14
The belt is most likely slipping. Make sure you are getting enough "belt wrap" around the pulley.
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Advanced
Joined: Mar 2006
Posts: 67
Likes: 0
Sorry for the long reply!
I am talking battery's internal temp and the alternators temp. As you charge a battery, it gets hotter as well as when you discharge one, it is one of the side effects of the chemical reaction. As for heat and connections, I agree that if you have bad connections you will have worse connections once they get hot. If you have an infrared digital themometer you can actually see the connections getting hot under load. Also make sure you alternator is grounded correctly and well to the frame and your battery is too. DON'T trust an ohm meter when checking this connections, as unless you have a milli-ohm meter the difference will be so small a regular meter can not resolve them. Use a regular volt meter and test volts. CAUTION - If you aren't comfortable with either working on a car with it running or your comfort level with electricity is limited to changing a fuse or light bulb stop! With the car running, hook the positive lead to the battery positive terminal and then check the voltage with the negative lead. Record the voltage. Then leave the positive attached and move the negative to another point, like the alternator case. If the voltage is more than a couple of tenths lower you have either a resistive wire or a resistive connection.
I am talking battery's internal temp and the alternators temp. As you charge a battery, it gets hotter as well as when you discharge one, it is one of the side effects of the chemical reaction. As for heat and connections, I agree that if you have bad connections you will have worse connections once they get hot. If you have an infrared digital themometer you can actually see the connections getting hot under load. Also make sure you alternator is grounded correctly and well to the frame and your battery is too. DON'T trust an ohm meter when checking this connections, as unless you have a milli-ohm meter the difference will be so small a regular meter can not resolve them. Use a regular volt meter and test volts. CAUTION - If you aren't comfortable with either working on a car with it running or your comfort level with electricity is limited to changing a fuse or light bulb stop! With the car running, hook the positive lead to the battery positive terminal and then check the voltage with the negative lead. Record the voltage. Then leave the positive attached and move the negative to another point, like the alternator case. If the voltage is more than a couple of tenths lower you have either a resistive wire or a resistive connection.