Replaced battery and alternator and problem still isn’t fixed?
I replaced my battery and alternator on my truck and it’s still doin the same thing before I changed it. When you turn the truck on the battery gauge will go up about a quarter past the 14 then start drifting back down then finally settles somewhere a little above halfway between the 9 and 14. Any ideas on why it is doing this ?
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Answers & Comments
Could always be a faulty guage
I have no clue why you would replace your battery and your alternator.
It seems that the "problem" occurs after you start the engine.
It appears that you have an overvoltage condition, based on your instrument panel voltmeter.
Step 1: Connect an accurate voltmeter to your battery. What does the voltmeter read before you start the engine, AND then after you start the engine? Above 14.4 volts? How high? If it goes high and then drops, what is the approximate voltage that it drops to? How long does it take to get down to that voltage?
MY educated guess is a voltage regulator problem.
Many alternators have the voltage regulator circuit within the alternator. But some vehicles have the voltage regulating function of the charging system in the ECM (the vehicle computer).
Can you identify your vehicle for us?
Did your vehicle ALWAYS do this, or did it recently start happening?
-Engine overhaul mechanic and general automotive mechanic since 1972
Go to an auto parts store and they test batteries and alternators for free while in the vehicle.
You may have bad connections on the instrument cluster.
Does the voltage go up when you turn on the headlights?
Most people don't replace their battery and alternator unless the vehicle won't start because of a dead battery!
Translation: I don't have a clue how to DIAGNOSE the issue, so I have been trowing parts at it hoping something works.
Solution: STOP trying to FIX the problem and get someone to IDENTIFY the problem.
Update to comment: NO, the problem WAS NOT diagnosed as a POSSIBLE anything. Possible is a GUESS, not a diagnosis. A QUALIFIED mechanic TESTS the alternator instead of merely replacing it.
You probably got a broken drive belt that you didn't check.
Apparently you haven't yet learned that blindly replacing parts without knowing the problem is an expensive way to try and fix a car. I'll bet the auto parts store loves you
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Is the battery charging or not? You didn't mention that important point.
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It IS normal for a battery to charge heavily right after engine start and it tapers off as it recharges. It would be useful to know if the battery is discharging or not. A simple check with an ammeter would be helpful. If you don't have one or know how to use one then go to an auto parts store and have the charging system tested. Most will do it for free.
This is normal. Once the amps needed to start the truck have been restored to the battery the rate of charge goes down to equilibrium. Enough to run the truck and its accessories. There are electronics now to scale back wasteful overcharging of the battery when not needed. You don't mention any non starting problems???
This is on a 2013 Chevy Silverado