Alternator bad?

[bobby.bettinger]

So I decided to get my less than a year old batteries to be checked at Autozone before the cold weather hits Va Beach. Guy tests the right side battery and it’s charged. Performs the alternator test and he says it failed and I need a new alternator? My battery gauge on my dash on warm days shows 13 volts while running and on cold days it shows 14 volts. How accurate is the Autozone alternator test? I’ll probably end up grabbing a multimeter at work and doing it myself.


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[KeepEmRollin14]

Those testers are not that great. Grab a multimeter and check to see what voltage output is. Best way is to have an actual scan tool hooked up to see what the alternator is doing. Those testers they have should full field the alternator so if it didnt do that then i dont think its accurate. That along with testing to make sure its putting out 1-1.5 more volts than battery charge is sufficient.


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[watersupply189]

I wouldn’t trust the auto zone testers. If your not having any issues at all and you voltage is reading what you said then I wouldn’t worry about it. Did you have the other battery tested? You only mentioned you had the right side tested?


2016 Ram Laramie 3500, G56, 6.7, MM3 tuned by Double R Diesel, Rough Country Leveling, 35x12.50 Nitto G2, HID headlights and fogs plus many many other add ons.....

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[bobby.bettinger]

I wouldn’t trust the auto zone testers. If your not having any issues at all and you voltage is reading what you said then I wouldn’t worry about it. Did you have the other battery tested? You only mentioned you had the right side tested?


2016 Ram Laramie 3500, G56, 6.7, MM3 tuned by Double R Diesel, Rough Country Leveling, 35x12.50 Nitto G2, HID headlights and fogs plus many many other add ons.....

Only tested right side.


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[KeepEmRollin14]

Could have failed if 1 battery was low. Check the other side as well.


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[watersupply189]

I agree! Why only check one battery and not the other? If the other one is bad then replace both batteries even if one is still testing ok. If you only replace one and not the other it could cause the new battery to have a much shorter life.


2016 Ram Laramie 3500, G56, 6.7, MM3 tuned by Double R Diesel, Rough Country Leveling, 35x12.50 Nitto G2, HID headlights and fogs plus many many other add ons.....

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[bobby.bettinger]

So i grabbed a multimeter at work at read out each battery. Both read about 12.7 with engine off. Read both batteries with engine running and both were at about 14.4. It took about 15 seconds for the alternator to take over charging batteries. I believe that's where the Autozone guy screwed up. He didn't wait long enough....

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[KeepEmRollin14]

Yep there good nothing wrong


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[watersupply189]

Nothing wrong with your batteries or charging system


2016 Ram Laramie 3500, G56, 6.7, MM3 tuned by Double R Diesel, Rough Country Leveling, 35x12.50 Nitto G2, HID headlights and fogs plus many many other add ons.....

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[Polaraco]

Best time to check the batteries is after it has set over night. Anything under 12.1 should raise an eye brow. I disconnect one battery and read them individually. That's how I found this one bad one I have right now

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