Hatred towards battery light

[Bwinn]

2007 audi A3 2.0T DSG: Battery light came on briefly at a stop on saturday then went away when
I started moving again, figured oh great time for a battery. Replaced battery. 2 days later the battery light came on again. Suspecting the alternator is bad at this point. Any thoughts or ideas?

[everfresh59]

buy a new one?

[rawaudi]

Load test the alternator.

[krazyboi]

i had bad battery issue...ended up being the electrical ground for the car. the wire was corroded through. i didn't notice the light though, just had starting issues.

[Bwinn]

Load test the alternator.

Turn on lights and blower and rear defrost and check voltage at alternator positive lug?

[VWAddict]

The "battery light" DOES NOT MEAN THAT THE BATTERY IS BAD.

What it is intended to signal is: "THE POWER IS BEING DRAWN FROM THE BATTERY AND NOT THE ALTERNATOR".

Hence... when the engine stalls (for example) the battery light comes on.

It was never intended to suggest a bad battery.

Check the alternator if it's not to much of a job, but first visually check all of the cable connections.

Since you did change the battery, maybe go back and make sure you used a liberal smudge of vaseline on any exposed copper strands, and ALWAYS vent the battery outside the battery cover, if your battery has a bleeder vent. -Failure to do so will cause the corrosive gases to collect inside the battery cover, and any exposed copper is the easiest thing to munch on... then you get hi-resistance paths, slow starting, poor charging etc. Keep air/gas away from the exposed metal (that's what the vaseline is for; it forms a very useful inert barrier) and you should slow or prevent problems like that.

[Bwinn]

Thanks I'll definitely check clean and Vaseline those, any info on checking the alternator?

[VWAddict]

Usually has to be done at an auto parts store... piece if cake to test, but it has to be removed from the car first...

....THAT'S the part that takes time (if you do it yourself) or money (if you pay someone to do it for you)

Then refit or replace depending on the test result.

I've taken the alternator out of several VW-Audi cars, usually to get to the A/C compressor... It's not as bad as all that, but allow an hour to ninety minutes to get it out... and make sure you have a big pry-bar or massive screwdriver, to lever it away from the block once the mount screws are removed. -Push the bushings in with a C-clamp to give you more clearance for refitting it, and ALWAYS disconnect the battery negative lead before you start... otherwise flashes, and welded wedding-rings (including loss of ring-finger...) etc are serious risks.


Always begin by checking the wiring for frays or corrosion first. -That means the BIG positive wires, and the smaller 'exciter' wires etc.

[Bwinn]

Thanks for info gonna rip it out after I check some wires.

[LWNY]

get a sharpie and blacken that section out. no mo batt light.

[krazyboi]

get a sharpie and blacken that section out. no mo batt light.

Best advice in this thread

[Bwinn]

Took it off and it failed at autozone. $225 for reman with lifetime warranty. Probably gonna go that route even though I'm not a huge fan of those parts stores.

[VWAddict]

Were my removal directions any help?

Also, on a 1-5 scale, how would you rate the pain-in-the-butt-ness of this project for others?

Thanks,
Keef

[Bwinn]

Directions definitely were a help. Also expect to take off serp belt tensioner. You will have to put a drill bit threw it to get the bottom bolt. I haven't reinstalled yet but the c clamp trick seems to be a must. Any ones thoughts on the autozone alternator?

[VWAddict]

Actually, I'd be fine with them.

All alternators work the same... there's bushings, bearings, field coil, armature, exciter coil and a multi-phase rectifier.,, they're all standard fare. Some have an external regulator arrangement, but that's less common.

If the warranty is lifetime, and you're okay with doing the labor yourself, then I'd say the lifetime guarantee makes sense if you plan on keeping the car. If you're ditching the car after a year or so... whatever is cheapest, I suppose... might still be the same answer.

Either way, there's nothing 'space-age' about the Bosch original (I presume they're using Bosch... maybe Densei or similar by now for all I know!) so I'd be quite happy to replace it with an aftermarket reman. product.

How much is the OEM from Audi, do you know?

Keef

[TBomb]

How much is the OEM from Audi, do you know?

Keef

LMFAO

$1200 for a brand new OEM alternator. $382 for a remanufactured one.

[Bwinn]

Mine actually had a valeo. I'm ordering from autozone Monday.

[Bwinn]

Installed and no more battery light! Test drive to werk tommorrow

[VWAddict]

Yabba-dabba-dooooooo!