Alt/Battery?

[BpuVR4]

Thought it'd be a simple situation, but it's a basic battery vs alternator q. I was driving home after doing some light work on the car the other night (oil, headlight bulb, tightening ic piping couplers). at one point the voltmeter on the turbo timer started flashing 11.4v. I was cruising 70mph on the highway, and wanted to just make it home. It stayed from 11.4-11.1v for about 15min. All of a sudden it jumped back up to 14.2v, and stayed there til i got home. This was all highway driving. Ran the car again today to see issues. Car started w 14v, then dipped to 11.3v 10min later and stayed there. I hear no belt squealing- thought maybe some oil spillage got onto the belt. Only accessory running were the headlights- i dimmed the dashlights all the way.

1. Im confused because I didn't think the car would stay running for that long with only 11volts, what's the lowest amount of voltage necessary? I'm kinda sick and trying to get her done in one shot. Not sure if I should try to chance a drive to autozone to get the charging system tested or not in current state.

2. The battery is a blue top Optima, clamps are only couple months old and clean. Is there a chance it could be the battery, and not the alternator?

 

[EMX5636]

Check to make sure the voltage at the battery is the same as displayed on the TT. I've had a lot of them either get a loose connection, or stop reading right. Your lights should have gotten dimmer at 11V. If you didn't notice at all, might just be a goofy reading.

 

[BpuVR4]

i wondered about that. however i thnk the batt light was starting to come on at certain points, but didnt stay lit either

 

[EMX5636]

If the Bat light was coming on it's probably a real issue. I doubt it's the battery but you could have it tested. Seems like a winding or the regulator has a loose connection inside the alternator. If so, it's time for a new one.

 

[BpuVR4]

Advance Auto Parts was only 4 blocks away, so I drove her over. Guy put on his tester, and flat out told me that the alternator was putting out absolutely nothing. Said battery was a little low, but good. So i guess that's that.

1.Also wondering how many connections to the alternator there are: the main 2 prong plug, one eyelet that gets bolted to the stud...any others? I saw an unconnected wire down there that leads to the mess with the 02 sensor and alternator wiring.

2. is jacking up the car to get the bottom bolt necessary? hoping not, as I wont have access to one for a couple days.

 

[BpuVR4]

forgot about the alternator fuse/relay, pulled it and this is what it looks like- is that gel like substance or whatever between the prongs normal? Also when I shake it, i hear something tiny moving around. trying to cover my bases here

 

[G]

Relay looks fine. More than likely your alternator is on it's way out. Sometimes they will intermittently not work when they are on the way out.

 

[BpuVR4]

yea...i shoulda stopped while i was ahead. in my delirium, I tried to yank out the 100a alternator fuse, forgetting that block is bolted in. all in all, gotta add that fuse to the shopping list goodness. i can surely be retarded sometimes.

 

[460GVR4]

Alternator. Go buy one and get the lifetime warranty. I have used that warranty about 4 times now after 3 dsms. Everytime mine went out the battery and coolant light would come on about 10 seconds before the car would shut down! Be glad you made it back. whole swap is easy without jacking it up you'll be able to do it in the dark soon!! Been there done that.

 

[BpuVR4]

yea, whole alt install took about 45min...the hardest part was twisting off the nut off the long stud one little turn at a time w my fingers. and yep you guys are right, next time will take a good 10min less...or ill just plan on doing it with my oil change so the filter is off. funny thing is, I had just changed the oil hours before the symptom started/

 

But if alternator was bad the car wouldn't start and if did it would've over heated and you're lights would've dimmed and turned off and so would've the car eventually. I think

 

[RayH]

When the alternator goes bad it will continue to run on the battery for a while. Depending on the battery capacity it can be 20 minutes or longer and if you stop before the voltage going to low the voltage will come up a little without a load but will drop quickly once you start the car.

 

[BpuVR4]

Quoting jertech:
But if alternator was bad the car wouldn't start and if did it would've over heated and you're lights would've dimmed and turned off and so would've the car eventually. I think



i got an Optima blue top in there, if that helps. I think i was fortunate enough to catch the alternater at the start of its way out.