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Discussion Starter #1
Yesterday morning I jumped in the car, started the car, the air pump sounded much louder than usual, to the point where most of the time I don't even recognize it anymore. But yesterday, it seemed abnormally loud.
I also noticed that after driving on the freeway for 13 miles and getting to the off ramp stop lights, the air pump was still running. :unsure:
I made mental note of that and was going to check it out when I got to work.
When I finally got to work, I was met by the security guard ( I was 2 hours early) and with that disruption I completely forgot about the air pump.
So last night at 6pm I jump in the car, shove the key in the ignition, first thing I noticed was a blank dash monitor. Checked the battery. ZERO volts. (n)
I'm thinking, crap, now I got to buy another battery.

My initial guess is, the air pump relay is stuck closed and the air pump ran until it drained the battery.

Looked back at my records, I purchased the battery in early 2013. Seven years on a battery. I can't complain about that.
I suppose I could try and recharge the battery, but with the inevitable onslaught of ridiculous temps coming in the near months, I'm not even going to think about it.
Seven years on a battery is stellar performance no matter what climate your in. It's just time.

I'll report back.
 

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With the heat, mine never last an average of only 4 years on every car I have owned down here. A new relay and battery will get you through the 8+ months of hot weather coming.
 

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The SAIP (373) relay can definitely fail closed and drain the battery. It's effectively undersized, and it and the 40A fuse are the only thing between the battery and the SAIP.

You'll find the contacts look like the surface of the moon and can stick together ("weld"). When mine failed, thankfully when I arrived home, a sharp rap on the ECM box opened the contacts until I could replace the relay.
 

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I just changed the battery in my wife's 2009 Q5 yesterday, and it might have been the OE. The battery compartment is more of less under the rear seats, so it stays looking like new. But there's more to replacing the battery than that; VCDS is required to adapt the battery to the 'power management system'. What I suspect is a battery current sense wire plugs into to a small box on the negative terminal clamp. I assume that alternator output is controlled by this system.

Incidentally, I wouldn't normally go to the dealer for a battery, but from what I read about this power management stuff, I went ahead and plopped down $248!! The parts guy, who has always given me a break when buying authentic Audi parts, told me that $248 was quite a bit less than list. On the other hand, the battery is an Absorbent Glass Matt type, which are said to be a superior type of Lead-acid battery. By the way, if their service department put it in, that would be $200 more!
 

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I did not know the Q5 put the battery under the rear seat. I had an Audi 5000S Turbo that had the battery there. It should last much longer as it's not in the nice warm engine compartment. I tried an AGM on my wagon, it lasted 4.5yrs. I am hoping to put the next replacement under the floor of the hatch, where one of the dual mufflers currently reside. VW made a similar setup for the R32:
 

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The new Audi (Valeo) battery says "Start-Stop" on it, apparently the AGM technology is what the shut-off/re-start at the signal cars need. This Q5 doesn't do that, but if this battery lasts as long as the original, I won't need to swap it out again. By the way PZ, I had two Audi 5000 turbos; one was an '81, beautiful red color but only around 130HP from what I remember, the other was an '86 CS Turbo. That was an impressive car for the time, but just trouble-prone in many ways. Some of that was due to the plastics used; radiator tank blew out, intercooler hose breaks, exhaust hanger failures, etc. The hydraulic brake booster system was atrocious, a power window motor burned up. The "diagnostic system" was prehistoric, but when running right, was a quiet, fast buggy. My next Audi, a B5 2.8, was simpler overall but also a major improvement in just about every way.
 

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2004 B5.5 Variant 1.8T
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I just changed the battery in my wife's 2009 Q5 yesterday, and it might have been the OE. The battery compartment is more of less under the rear seats, so it stays looking like new. But there's more to replacing the battery than that; VCDS is required to adapt the battery to the 'power management system'. What I suspect is a battery current sense wire plugs into to a small box on the negative terminal clamp. I assume that alternator output is controlled by this system.

Incidentally, I wouldn't normally go to the dealer for a battery, but from what I read about this power management stuff, I went ahead and plopped down $248!! The parts guy, who has always given me a break when buying authentic Audi parts, told me that $248 was quite a bit less than list. On the other hand, the battery is an Absorbent Glass Matt type, which are said to be a superior type of Lead-acid battery. By the way, if their service department put it in, that would be $200 more!
Both my B8.5 A4 and 8R Q5 have it in the spare tire well. The spare fits over it. Many have gotten replaced it without needing any coding, but it is still recommended for the reasons you suspect.
 

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I know the 2014 MY and newer Audi A6 Allroad has the battery in the rear below the spare.
 

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The Tiguan has it up front, just like our 05 Golf. I expect it will eventually end up in the back too.
 

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Discussion Starter #11
UPDATE

Yep, Relay 373 was stuck in the closed position. As soon as I hooked up the new battery the air pump started whirring away. Pretty loud too. Bad bearing.
The relay contactor was stuck pretty good.
Will have to hunt around for a replacement air pump.
Other than that, I'm back on the road.

Purchased an Interstate battery. $206 for a 6 years, 3 year 100% replacement guarantee, pro-rated after that. (y)
 
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