What is the proper voltage reading
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Joined: Jul 2004
Posts: 54
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From: New Fairfield CT
I run on average about 13.7. Starts around 14.3 cold for the first minute and as I drive throughout the day it will slowly drop to about 13.5. Rarely, but sometimes it will hit 13 after a long day.
Next day it repeats the same cycle.
Next day it repeats the same cycle.
Drifting
Joined: Mar 2004
Posts: 1,672
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From: cincinnati ohio
Senior Member
Cruise-In V Veteran
Originally Posted by Perceval
I run on average about 13.7. Starts around 14.3 cold for the first minute and as I drive throughout the day it will slowly drop to about 13.5. Next day it repeats the same cycle.
First is with the engine off. Then you are just getting a reading of the battery's quiescent (static) voltage.
Second is when the engine is running and you will be receiving the alternator's voltage. It is the alternator's voltage that will vary the most. Why / Several factors. One is that you may be running several accessories that will drain some of the operating voltage. That will put an additional load on the alternator. As you turn off the A/C and then the radio and then the lights etc., you will see the DIC reading for the alternator's voltage change as the load changes. You can also get a changes like that when the engine is not running (alternator not turning then) and the sole source of voltage is the battery. Then the various accessories are presenting a different load on the battery which when the engine is not turning the alternator is the sole sourc of power (voltage) in the car.
Two different readings. Remember the function of the battery is to do two things : 1) power the accessories (lights, A/C, radio etc.) when the engine is not running .. . . if you do that for too long you will run down the battery (but you all knew that already). The other reading is the alternator when the car's engine is running and turning the altgernator. Then the battery no longer powers the car's electrical system. It is the alternator that is powering the car. The reason you can get quick changes in the DIC readings with the alternator as you can turn on and off the various accessoris thus changing the load to the alternator. As the load changes the voltage will change too. The reason and explanation for that is too long for this post.
DIC's reading for the battery in its quiescent status changes but more slowly for the same reason above which I am not getting into.
Whether you have a Delco or Red Top is meaningless on the readings
