Inconsistant Voltage

[DKneble]

Had something weird happen last night that I have never experienced before and was hoping for a second or third opinion.

As I got to my destination last night, after driving for about 20 minutes, I noticed my battery light flickering as I pulled in to park. While sitting at idle my voltage guage was reading about 11.5-11.8 volts, typically around 12.7-13.0 for me. So my first thought was great!...alternator is dead! But I had just replaced it about a month ago so I was both confused and frustrated. I said screw it and went inside the store to do my shopping.

When I came outside an hour later she started up fine and the voltage was back to 13.0 with no battery light flickering. I didn't argue and I drove her home for the night. This morning she ran fine again with no voltage issues.

In my experience when an alternator dies...its dies and doesn't fade in and out. Same with a battery. So I checked my wire connections and everything is nice and tight and clean on the battery and alternator. Can't see if I have any cracked wires though. Any ideas?

I was figuring that a shorted out connection was probably the most likely cause of the problem but shorts usually don't fix themselves while sitting still in a parking lot. Also last night was the coldest it has been here all year...36 degrees (florida). Finally, I think I drove through a puddle about the time this all started and I have an inline fuel pump under the car (bosch 044) with exposed connections...possible cause?

Thanks guys.

 

[Puscifer]

With our whacky weather and stuff we've been getting this season it's not been to fun on the rides. What kind of alternator is it? I've got a couple junk ones in the past, namely from Advanced. Quickly learned not to do that! So, I got a bosch and haven't had any problems since. Alternators can flux like that but if you go more than a couple days without getting more than 13.0v I would take it back to where you got it to get tested before you worry to much.

Fuel pump - that's a nice pump man, cover it up! I believe if the exposed wires were the cause you'd have other effects with the low volts that you're getting. Possibilities are endless though.

 

[the_mork]

Take the leads off of your battery (all the way off) then put them back on. Battery posts are tapered and even what appears to be a tight connection may in fact be causing greater resistance than necessary.

36 degrees really shouldn't be cold enough to cause you any problems so I doubt the weather would be a culprit except if you have a loose or bad belt. As the temperature drops belts become stiffer which allows them to slide on the pulleys instead of pulling them around. It is also possible that the puddle you went through caused the belt to get wet and slide on the pulley. Inspect your belts and see how much deflection you have.

 

[DKneble]

Update:

Drove it today and it worked fine on the way to get dinner. When I started it up after dinner the voltage was back down again and the battery and brake lights were faintly flashing. I nursed it home on 11.5 volts and about halfway there it went back to normal. WTF

Battery connection is good, belts are tight and the water doesn't seem to play any role here since there were no puddles today. Seems like when the car has been running but not a lot of airflow going through (ie just after parking when everything is heat soaked) is when it occurs. I know heat can kill alternators so I'm going to be pissed if I need to replace this thing for the third time in 6 months and I have a heat shield on it too. I have just never had a case where it fades in and out like this.

I'll check wires in the daylight tomorrow and probably yank and test the alternator...sigh.

 

[->PrOjEcTGS<-]

Your voltage regulator in the alternator is taking a dump... Go have the thing tested.

Our alternators are known to be problems. Especially when you replace them with the crappy units that they sell at most parts stores.

 

[Defiant]

While sitting at idle my voltage guage was reading about 11.5-11.8 volts, typically around 12.7-13.0 for me. So my first thought was great!...alternator is dead!

The alternator already was dead. The slip ring carbons are used up.

 

[DKneble]

Thanks defiant, ill yank it today and get my freebie from advanced...I don't have the money right now for a bosch.

 

[DKneble]

Alternator replaced, the old one was only putting out 5 volts. This fixed my voltage issue but the next day when I started the car the battery and brake lights would flicker on and off. What can cause these two to intermittantly display while driving and while I have good voltage (13+)?

 

[DKneble]

The regulator is the only thing I can think of but to really have two alternators go bad in one week? Is there anything else that can cause it? Battery seems to be fine btw but I'll clean up all the connections again tonight.


Voltage today varied between 11 and 16v, causing all my sensors to act crazy. Regulator is obviously bad. Going to advance auto to complain and get a replacement...wish I could afford the Bosch. I'll post if the next one works or not.

 

[->PrOjEcTGS<-]

Autoparts store's alternators in general are known to not be put together well and fail quite frequently. On my old Ford F-150 I kept trying to trace a problem with my truck but I kept overlooking the alternator because it was "brand new" and of course a brand new alternator couldn't possibly be the problem. Go figure. It was the problem. I would rather go out to the junkyard and pull a used one out and use that than getting one from any autoparts store.

 

[Puscifer]

make them test the one out of the box you're trading in for. if the voltage doesn't satisfy after they run it for 2+ minutes (make them do it) then ask for another. it's your money and their business.

 

[DKneble]

New alternator on and problem appears to be fixed...at least for now. Thanks guys.

 

[Jetrosr]

Been fighting the same thing. Check your battery connections, make sure you can give them a pretty stiff tug without moving them.

Drrr, sorry, somehow I missed all the posts after the first one.

 

[Puscifer]

Kudo's man. NEVER trust and lower scale OEM spec replacement parts from retail stores. Namely remaned. They hate me because I always insist upon them doing a durable test on electrical componets before I leave. Wise thing to do.