I know this isn't the fix, but it may help settle your aggravation in the mean time.

VW's used to ship with a solar charger that would plug into the canbus and had suction cups for the drivers window or windshield. You can find them on eBay usually.

Or, If you park in a garage or near an outlet, a battery tender would help.

Letting the battery completely drain is very hard on them and they usually don't recover from it after a few hits.

After you find the excessive draw, you may need to invest in a new battery yet again.

You need to hook up
A multimeter to the battery and start pulling fuses to determine the area where the draw may be coming from. Seems like the dealer should have done this.

 

Yup, a battery tender is pretty much always nearby these days. And the dealer is replacing the battery. Again. Third one in a year under the battery warranty. As for solar chargers as stuff, that's fine for me. But no way I'm having my wife drive a car that needs a solar charger stuck on the dashboard when she parks in order to start reliably.

But the dealer hasn't done the fuse/voltage testing at this point, since hey are claiming that 150mA is normal, they don't think there is any excessive current draw to find. That's what I'm focusing on finding out right now... Is the 150mA within normal range?

Of course the dealer logic fails at some point... If the charging system is o.k., the current draw is normal, and the battery is new, then it's hard to explain why the voltage drops to 10.5V after sitting for a week.

 

Lets say it is 150 mA draw in the parked mode with all modules in their low power state. This is 3 Amp-hours per day. The Touareg primary battery per VW specs shall be rated 95 amp-hours (AH) or better.

Amp-hours is based on how many amps x hours can you draw from a fully charged battery before its voltage drops to 1.75 per cell (10.5 total), at a power drain rate equal or less than 1/20 of the AH capacity. So, a Touareg that did the worst case 3 AH per day draw would need to be charged at least every 30 days to keep the battery cells above the recommended minimum of 1.75 volts per cell (10.5 when measured across all 6 cells) that maximizes battery life. The AH capacity drops over time as a battery ages so an older battery will be less than 95 AH. You can maintain your battery with an intelligent charger that reverses sulfation and make the AH capacity decline take longer.

I suspect that a lot of Touareg's draw less than 150 mA when in low power sleep state depending on how they are equipped. Might be where the 40 mA came from is that is best case for some that don't have as many convenience options.

Personally I wired a permanant 2 pin RV style 12V connector with weather cap for a Sears Diehard 2A 12V battery charger/maintainer on my Touareg primary battery leads (I tied in to the wiring where the jumper cable posts are under the hood) and plug in the float charger whenever it sits for more than a week. If parked outside the solar panel based solution would work but due to how the 12V power outlets are wired where they are disconnected from the 12V primary battery leads in sleep mode you would have to figure out a way to connect the solar panel to the always hot side of the 12V system so that it would actually charge the battery while in sleep mode.

If one goes the solar panel route if a basic one with no charger/maintainer circuitry is used and it can put out more charge than what the drain per day is, then it may cause the battery to be over-charged which would be a pain on a Touareg where you can't easily get to the cells to add water to the cells to compensate for the water loss caused by overcharging.

 

@pfb

I see that your Treg is a 2004MY. That probably rules out the satnav with hard drive as an installed option?

I discovered that the RNS-510 satnav system in my 2009 T2 will occasionally continue to run the hard drive after the vehicle is shut down. If the hard drive runs overnight it will easily discharge the battery below starting voltage. I am told that a software update to the RNS-510 will cure this "hard drive run on" problem.

Probably not a contributor to your phantom electrical drain problem...?

Moto

 

Is the alarm setting? any aftermarkets on your rig drawing power after shutdown? All lights are extinguishing when doors are closed?

Unless you know that it is a sleep draw causing battery drain, for the money, I would go with a complete charging system and battery check at a reputable indy shop NOT the dealer...and most importantly make sure all charging cable connections are clean and nutted securely. If this proves futile or you are sure that it is sleepdraw, if you can get the treg to sleep and retain access to the fuses (not sure if this is possible), you can place a voltmeter on the individual fuses and identify big draws. This is an easy no-cost DIY.

You don't want to go down the tracking and checking vehicle wires for resistance issues, groundings...route. It can get very expensive and probably is not necessary

 

bringing this back up as I'm now running into a similar problem - I believe my kessy is bad, so when the alarm is set, it drains the battery because of constant ping to the antennas in the doors.
I'll be repairing the kessy and hope that the problem will go away, but since the OP didn't have a bad Kessy, it got me to wonder what 'else' it could be.

Hope someone can chime in!

 

I have heard that the car will not sleep unless the alarm is armed.
Unfortunately location of the fuse panels dictates open door access.

 

How close is the key to the car when slumbering? Too close a distance and the 'pings' to antenna are very likely to occur.

 

I've now joined the dead battery ranks. With the strap between the battery and the chassis disconnected and replaced with an ammeter I pulled all of the fuses one at a time. Current stayed very constant at 2.5 amps. This was with one door open so I could get to the fuses. Closed the doors and locked the car by pushing the button on the key fob (I don't have kessy) and the amp draw dropped to 1 amp.
1 amp is still enough to make the battery go dead if I don't drive it everyday.
The connection to the ground was very clean. I haven't gone after the cable from the battery to the alternator yet as that looks like it won't be fun or easy. Any thing else I should check?

 

After doing everything that has been listed in this thread I finally put in a batter disconnect (like a racecar) between the negative terminal of the battery under the seat and the ground lug in front of the battery. This is a 2004 VW V8 with the minimum accessories. If I remember to throw the switch to off then the battery never is dead.
I did have one funny thing happen. My wife was starting the car and did something that made the alarm go off. Normally we never set the alarm since the battery is disconnected. But in this case after I threw the battery switch to off the alarm continued to sound albeit a much lower volume. Turning the switch back to on and enabling and then disabling the alarm made the alarm go off. Any idea where the alarm was getting its power. I understand the purpose of having an alarm that sounds if the battery is disconnected I just don't know where the power is coming from.

 

I found my battery drain from my steering column electronic controls not allowing the convenience module to sleep. If you have the electronic tilt column, try pushing the circular button so it is off (stands higher when off). This way your seat and steering column will not move out of your way each time you enter and exit car. The exact cause was later found to be the drivers seat belt upper tensioner position motor would not park it self and kept powered up trying to move.

It's easy to check consumers. you can move the striker to closed position in both front door latches and leave them open to access fuse panels. Make hood striker closed too so it thinks it's closed while open and you can pull relays for testing power draw.

I installed marine battery switch between ground strap connection, and added ammeter. Turn off switch with ammeter installed in parallel.

Press the key-fob lock and watch ammeter and you'll see the different stages of sleep occur when amps reduce. Put key in house when doing this. You can stab backside of fuses with voltmeter and see whats hot and whats not. There are also alot of fuses and relays under drivers seat.

btw, there is a counter for each time the car looses power in the kessy module. When it reaches a number like 49 times or such, its limit, it messes with the alarm. The security system will blink your flashers like 38 times each time you lock your car. The alarm will sound also each time you unlock your car and immo locks you out until your key fob is realigned with kessy w/2 key on/off cycles. You need to go into adaptation (forget the field like 02, or 03), and you'll see the big number, simply set it back to zero. (using vagcom with vehicle login for adaptation maintenance of course).

I also figured if you get out and walk around to front passenger side door and hit door lock switch and close door, this locks the car but doesn't arm the alarm and prevents battery drain since the alarm is not polling the system waiting for sleep mode. It just sleeps without the alarm function. Notice the red blinking led on the drivers door lock is not blinking. I could talk for hours about these trucks, since I bought 3 of them from auctions (dead non-running) with all these problems and spent the last 3 years on special project learning the kessy module function, and immo delete.

Jeff

 

I went through the process of pulling all of the fuses and sitting in the car as it went into sleep mode watching an ammeter. It would finally stabilize at 2 amps which meant the car was dead in 24-48 hrs. My Touareg doesn't have kessy although it is interesting that the ignition key works like a button. Turn it clockwise and immediately release it and the car starts. I'd been treating it like a normal turn the key and wait until the vehicle starts for years until I noticed that I didn't have to hold the key. But I do have to put the key in the ignition to start the car. Duh. I didn't realize there were fuses and relays under the seat until I replaced the battery and by then I was so tired of messing with it that I didn't bother to pull them and see what happens. Next time I have the seat out I will see if pulling any of them reduces the 2 amp drain. Thanks for the info. I really like the Touareg - 130,000 miles and all I have done is timing belt, oil and filter changes, and curse the electrical system;-)

 

Key locked in ignition. Battery dead , hooked up low amp charge dash light up but nothing. Tryed jumping no electric at all. 2005 v8 Tuareg.

 

The short answers are probably best. Discussion can flow later.

Buy and deploy a battery trickle charger.

Put any to all ones' cars on some battery trickle charge schedule.

The goal/concept here is to get the battery up to 100% from 80% and below (again, at some periodic schedule) . The oem charging system is NOT designed to get the battery back to 100%, let alone KEEP it there. It is wishful thinking to expect the VW Touareg PACKED to the gills with electronic do dahs NOT to draw current. This does not even address a user's customized demands.