Battery dies randomly

B6/7 S4/RS4
#1

Ok this might be a stupid question, but it has happened twice to me in the last 2 months.

Background:
I DD my b6. New battery was put in 2 years ago.

Issue:
Last month and then just last week, I get in my car to head to work and it doesn’t start. Just dead as soon as I start cranking “click-click-click-click” and suddenly it’s 2003 again. Started and drove great all the other days.

Troubleshooting:
I am 99.99% sure I didn’t leave lights on, door open, phone charger in, etc. Both times I just jumped with my wifes car and drove to work (30miles) and its starts/run fine otherwise. I figure if its the alt or battery itself I would get 2 miles down the road and it would die. This is not the case. Again, both times I’ve just jumped it and it drives just fine, never hooked up a charger or anything. Drive it everyday…

Question:
Did something simply get “left on” both times (even though I am pretty sure noting did…)? Or is there anything that could cause the battery to randomly puke out once a month. No CELs other than my SAI and occasionally a “Cooling Performance” code that I still need to sort… (btw this is scanning w/torque, not VCDS).

Any thoughts? Thanks guys

#2

do you have navi

Another thing that can do it is the pump for the performance cooling code could have gotten stuck on and drained the battery. Not to sure that would be it but that could have been it.

The cars have a good draw on the battery with the car in normal conditions. If the battery was weak that could have just put it over the edge. Also check the connections a loose connection can also drian the battery

#3

Thanks for the thoughts Justin.

No I do not have the nav system. I’ll check any connections I can get to this upcoming weekend. Not sure what I can am going to do about the cooling code yet, I need to get a legit scan done. I already changed the tstat so I need to troubleshoot it more. thanks

#4

ohh. You should have posted here. The T stat wasnt the issue. The performance coolant is the pump on the driver side. Its on the Aux rad. Its like a after flow pump. It could be running non stop and killing the battery. I dont think thats the issue for the dead batt

#5

The cooling code I am getting once in a while is P2181.

Only seems to happen when it is cold out (<35F or so)

#6

Do you have the freeze frame data for the code. That will be helpful. Is the battery dieing in the same temp or having issues in the same range

#7

I don’t have freeze frame data (no VCDS, just Torque app).

Battery was dead again after sitting the weekend (20-30F). Is my battery just going bad? (only 2 years old, but it’s just a walmart one). How do I test/prove this? The battery has a 3yr warranty.

P2181 still comes back. Comes back when it takes the coolant temp (on dash anyway) a long time to get to operating temp, if it ever gets there. I initially thought my tstat was failed open or something but replacing that didn’t help. What else could cause that? You mentioned the pump on the aux radiator but I wasn’t sure what you were saying

“The performance coolant is the pump on the driver side. Its on the Aux rad. Its like a after flow pump. It could be running non stop and killing the battery. I dont think thats the issue for the dead batt”

You mean it runs nonstop while the car is running? Or when car is off as well? And how would that affect the battery if it is only when the car is running? Sorry, I don’t understand what you were saying. Thanks

#8

Cold weather can take its toll on a battery as well. It could be the battery being old

its easy to check. Every day before you start the car put a volt meter on the battery and see what its reading.

That will tell you how many volts the battery has. What it wont tell you is if something was drawing voltage from the battery to drain it.

#9

The other morning (Monday) when I went to start it and nothing happened, when I hooked up my battery charger it showed 12.2 volts (before it began the charging sequence).

Is there a way to test draw on the battery? (at any time) or is that just shown by taking voltage readings over time?

#10

What you want to check is the battery voltage when you go to crank the car. that will tell you what power is on hand. chances are it was well below 12.2

Testing for a draw on the battery is possible it just takes some work.

#11

alrightly. Now to convince the wife I need a Fluke115 8)

#12

No need for a fluke! Although I like your taste in electrical tools. And nice Artic white B6.

For starters, yes your battery can be toast in only two years. Alternators are considered a very low wear and tear part, but I’m pretty sure I remember hearing that the life expectancy is about eight years. So if you have average mileage for the year your car was made, and the alternator has never been replaced, then your alternator might be getting tired (but not dead).

A tired alternator puts out lower charging voltage than normal, and basically this means that your battery doesn’t recharge as strong as it should. And the deeper your discharge a normal car battery, the more it gets hurt. So cold starts - which are a big drain - are really hard on a battery in a vehicle with a pooped alternator. Not saying this is your problem, but it may be.

If your alternator is weak, then you’ll probably toast a battery every couple of years. Even with a good alternator, a decent battery only lasts about five years up here in Canada (results vary with climate).

#13

You can check the voltage on your battery, AND the voltage output of your alternator, all from the driver’s seat of your car, using a tool worth less than five bucks - a lighter adapter voltmeter. This gizmo shows voltage, and plugs into the 12V socket.

There are at least a couple of types.

A simple type with little lights on it, showing voltage ranges (red/amber/green health). I got one at a place called Princess Auto in Canada. There is a red/amber/green health light for both your battery and for your alternator.

Another type tells your exact voltage reading, and you refer to a chart to determine the health of your battery and/or alternator.

A quick search on eBay for “12v voltmeter” turned up eBay item 191751571735 (enter this number in “Search” field on eBay home page). This is the type that shows the exact voltage output. It also doubles as a cell phone / usb charger. Less than five bucks, including delivery, to your door. Until Trump imposes taxes on things from China!

Maybe you already know this, but to check your battery voltage, check the voltage with the engine off (Audi 12v sockets are powered even with the engine off). To check your alternator output, check the voltage with the engine running.

#14

This is the type with the “health status” lights on it:


http://audirevolution.net/addons/albums/images/172186711.jpg

#15

This is the type that shows exact voltage readings:


http://audirevolution.net/addons/albums/images/845404559.jpg


http://audirevolution.net/addons/albums/images/657280886.jpg

#16

Along with handy chart for interpreting your voltage readings:


http://audirevolution.net/addons/albums/images/117857763.png

#17

If you need a new alternator, a possible cheap alternative would be getting the voltage regulator replaced by a specialty shop. Their charge to pull your alternator and re-install it with a new voltage regulator is cheaper than paying Audi to pull your old alternator and install a new one.

Another consideration if you decide you need a new alternator - if you’re a hands on guy - is to get a used alternator from an online retailer like eBay’s Wolf Auto Parts. Or from a local scrap yard. Take it to the specialty shop and have them install a new voltage regulator in it. Cheaper than new, and remanufactured. This way you can install the “new” alternator at your leisure with no down time. Or, install the used alternator and check it’s voltage output before paying for a new voltage regulator, since the alternator is considered a very low wear and tear part.

#18

One other thing that might be your prob. I owned an A6 once that had a bad fan control module (I think that’s what it was called). Sometimes with the car off, the interior dash fan would blow, even if you turned off the fan before you shut off the car. So listen carefully for a few moments with the windows up after you shut off the engine.

#19

If you have access to plugging the car in, then consider a CTEK battery charger. They can be plugged into your lighter adapter, or permanently installed under your hood, or just applied to battery terminals in the garage with good old alligator clips. Basically, when you plug in your car, you plug in a smart trickle charger to your battery. One of these chargers was suggested to me by my local Audi parts counter guy instead of a block heater (he talked me out of a block heater).

I regularly abandon my vehicle in -20C and/or -30C for two weeks at a time, with a weak alternator, and it still starts when I get back to the city because the battery has been plugged in the whole time.

I can give more info on the CTEK, and permanent install, if you want more info. Getting one of these chargers wouldn’t track down your exact battery draining issue, but it would almost certainly alleviate your problem if a weak battery in the cold is your problem. If a weak battery in the cold is your problem, and the CTEK doesn’t help, then your battery is shot.

#20

Boatmobile, thanks for all the tips!

That little adapter seems nifty, I might give that a go first.

RE: Alternator. As far as I know it is OEM, so 11 years old and 182k miles now! Hopefully it is not that though. Although if it is, that would probably give me the chance to change the oil cooler seals as I am pretty sure they are leaking oil everywhere…