Alternator is on its way out.. help
06-12-17, 06:29 PM
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Alternator is on its way out.. help
I believe my alternator is on its way out. My car is a 2002 IS with 94k miles on it. It's my first car and my daily driver for 14+ years. I was never a car guy but I would like to learn so I can do maintenance on my own cars.
I used a multi-meter and here are the readings..
With the car completely off, the battery holds at 12.69 volt.
When the car is on, the battery is around 13.77 volt.
With A/C on full blast, radio, headlights on, the reading drops to 12.5 volt.
Extra info if it helps..
Car is completely stock. The outside temperature was at 95ish degrees while I was testing the battery. I drove the car home from work and turned the car off. I waiting about 30 mins before I decided to test the voltage. Car still turns over and drives fine but after finding out voltage being below recommended level, I am a little nervous about driving it.
How difficult is it to replace the alternator? I see that I can buy one online for around $100ish so if the job is doable for a newbie like me, I would love to get it done myself.
EDIT:
Just tried it again w/ the multi-meter..
When the car is at idle it's still at 13.77 volt.
But now when I have AC on full blast + just the headlights and radio, it's around 13.2v.
With AC at low setting + headlight and radio and it's at 13.6ish
Only time the voltage dips below 3 is when I have AC + defogger. Full blast AC + defogger will dip the voltage to 2.5-2.6 range. Defogger + AC at low setting will drop the voltage to 2.6-2.7. Outside temp is around 80 degrees.
I don't understand why the reading is different than when I first test it out.. Anyone know?
I used a multi-meter and here are the readings..
With the car completely off, the battery holds at 12.69 volt.
When the car is on, the battery is around 13.77 volt.
With A/C on full blast, radio, headlights on, the reading drops to 12.5 volt.
Extra info if it helps..
Car is completely stock. The outside temperature was at 95ish degrees while I was testing the battery. I drove the car home from work and turned the car off. I waiting about 30 mins before I decided to test the voltage. Car still turns over and drives fine but after finding out voltage being below recommended level, I am a little nervous about driving it.
How difficult is it to replace the alternator? I see that I can buy one online for around $100ish so if the job is doable for a newbie like me, I would love to get it done myself.
EDIT:
Just tried it again w/ the multi-meter..
When the car is at idle it's still at 13.77 volt.
But now when I have AC on full blast + just the headlights and radio, it's around 13.2v.
With AC at low setting + headlight and radio and it's at 13.6ish
Only time the voltage dips below 3 is when I have AC + defogger. Full blast AC + defogger will dip the voltage to 2.5-2.6 range. Defogger + AC at low setting will drop the voltage to 2.6-2.7. Outside temp is around 80 degrees.
I don't understand why the reading is different than when I first test it out.. Anyone know?
Last edited by WeiY; 06-12-17 at 09:21 PM.
06-13-17, 07:34 AM
#2
How old is the battery? Your readings seem pretty normal when the car is running, but a reading of 12.5V from the battery when the car is off seems a little concerning. It should be above 13V and the batter is an integral part of the electrical system. If it is going bad, you could be having a lot of ripple. Go to Autozone or Advance or some other place like that and they will test the whole system for free and tell you what is wrong. If you find the alternator bad, replace the battery too as a dying battery can take out a new alternator in a heartbeat.
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