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Old 08-28-2018, 10:27 PM   #1
Hamster
 
Drives: 2009 5-Door Liftback
Join Date: Jun 2011
Location: Columbus, OH
Posts: 231
Is my alternator fine?

So, my battery finally died. It's the original battery, and lasted just over nine years. Not bad! Anyway, so I call AAA and a tech comes out to my house to replace the battery. In addition, he ran some diagnostics. Under the charging test, the device he used to test the alternator showed the No Load Voltage at 13.83 V (this was the car idling), and the Loaded Voltage at 13.69 V (this was when the car was in park, with me pressing lightly on the gas pedal). The AAA guy said that these numbers are on the low end of normal. He explained that the low reading could either be because it was a brand new battery, or the alternator might be on the way out. He recommended that I take it to a dealership for further testing.

Since I'm not mechanically inclined, and I'm female, I'm worried that if I go the the dealership, they'll tell me my car will explode if I don't get a new alternator. So, do these readings show that I may need a new alternator? Or are they low because the battery is new? The car still feels like it runs like new. Would not doing a whole lot of driving shorten the life of the alternator? The car's got only 27,000 miles on it. Since I take public transportation to work, I only drive the Yaris on the weekends, and it's mostly city driving. I drive on the freeway only a few times a year. Thank you in advance!
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Old 08-29-2018, 08:03 AM   #2
dogsridewith
 
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Would be nice to know the everything-off battery voltage too.
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Old 08-29-2018, 08:26 AM   #3
nortonfb
 
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Get a cheap voltmeter and check it yourself with acc running and off.
You should be outputting AROUND 14 V.
Too much is bad as well as too little.
Your current output is fine.
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Old 08-29-2018, 09:06 AM   #4
tmontague
 
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You're fine, my 2zr swapped alternator charges at just above 13v when charging my brand new battery. I have a slight under drive crank pulley but even with slightly throttle it was similar.

Drive it until you have any serious issues. If the alternator isn't charging you will have your dash light up like a Christmas tree and potentially lose power as if the car was is limp mode
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Old 08-29-2018, 09:17 PM   #5
Hamster
 
Drives: 2009 5-Door Liftback
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@dogsridewith
Here's what was on the printout after the new battery was installed. Not sure if anything here is the everything-off battery voltage. I'm not knowledgeable about electrical stuff. I do basic maintenance on my car, like oil changes, but that's the extent of my mechanical knowledge.

BATTERY TEST
Rated: 360 CCA
Measured: 794 CCA
Voltage: 12.52 V
Temperature: 94 degrees
Cranking Capacity: Good
Reserve Capacity: Good

STARTING TEST
Voltage: 11.35V
Cranking Current: 11.0A

CHARGING TEST
No Load Voltage: 13.83V
Loaded Voltage: 13.69V

DRAIN TEST
Current: 0.00A

@nortonfb
Yeah, the tech said that 14V is ideal, and mine was a little on the low side, so he recommended further testing. But, it's still in the normal range. He might have told me to get it tested just to cover his @$$. But I'm hesitant to go get it tested at a dealership or a mechanic, because I don't want to be ripped off by someone who has an agenda to sell me something. But yes, good idea, I can go buy a voltmeter and test it myself.

@tmontague
Thanks for your reassurances! Sounds like the low-ish reading is normal given the circumstances. I have never experienced any loss of power, or really any problem with this car. I would be truly shocked if an important component like the alternator were to fail. Toyotas are built to last.

Thanks everyone! This forum is such a great resource!
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Old 08-29-2018, 09:32 PM   #6
06YarisRS
 
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My 2006 Yaris produces ~ 14.2V, engine running. My 2008 Yaris produces ~ 13.8V running. No issues at all with either. I did replace the alternator on my '06 when I first acquired the car, but it had a bad voltage regulator (it's on the alternator itself) and a corresponding dash light. The upside is that remanufactured alternators for these cars are not overly expensive. If you do replace it eventually, it is easy and you can do it yourself and deprive the dealership of your money. We will show you how.

EDIT: Also, these cars do not have an automatic belt tensioner. I wonder if your belt has enough tension. Do you have any belt noise at all?
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Old 08-29-2018, 10:03 PM   #7
Hamster
 
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@o6YarisRS Nope, no belt noise, or anything unusual. The car drives, feels, and sounds exactly the same as when I bought it nine years ago.

Last edited by Hamster; 08-29-2018 at 10:04 PM. Reason: Correcting grammar
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Old 08-30-2018, 02:38 PM   #8
bronsin
 
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I will sure wish I could get one of those OEM battery is like they put a new cars!

BTW the output of the alternator of my new police car (2010 crown Vic) At idle is 135 A. At 2000 RPMs it’s 200 A!
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Old 08-30-2018, 09:05 PM   #9
Hamster
 
Drives: 2009 5-Door Liftback
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@bronsin I so wish I could get one of the OEM batteries, too! Nine years! Now that's a crazy long time. And the battery wasn't even completely dead. There was still enough power to run the radio and turn on the headlights. Just not enough power to get the engine started.
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