Battery Displacement

[nene]

Can anyone with a non-US car post of send me pix of where your battery is? I heard that non-US cars have the battery on the spare wheel location, and I'd like to see some pix if possible.

I'm hoping to do the same, and see how feasible it is. Check how it all fits there and stuff.
Thanks for your help.

[Nordschleife]

The battery in non-US RS6s is in the wheel well.
The reason the battery was moved from the wheel well in US cars was because the charcoal breather vent container, attached to the fuel tank, is placed in the centre of the wheel well. This means there is no space for the battery. The battery is very large because it is so far from the engine and needs to be more powerful than normal in order to deliver sufficient current to the starter.
Modern battery technology would allow you to have a custom battery loom made and use it to connect up several high tech batteries in several vacant spaces in the rear quarters of the car in order to deliver similar performance.
As you might imagine , this solution is not cheap.
The battery was moved from the front to the rear in order to help with the weight distribution.
HTH
R+C

[nene]

It does not bother me too much that the battery is all the way in the back. However, it would have been nice to have it in the wheel well for example, where it does not take up trunk space.

I'll have to find a good battery shop that can give me some solutions.

[Aronis]

I am sorry, but I refuse to believe the battery needs to be a higher rated battery ie. bigger, simply because it is 8 feet further way from the starter!

No way.

The battery in my A6 4.2 was the same size battery. I still have the dead battery from my A6 in my shed. The battery I replaced it with was a Sears Diehard with similar amperage ratings which was 1/2 the physical size! The first battery was dead after less than a year! The second was going strong after 18 months or so despite the fact that it was smaller.

So, the battery size is the same for both cars and it's not bigger due to the extra few feet of distance to the starter!

The space where the battery lives in a 4.2 is taken by the radiator overflow tank! But this physical space is the same as it is in the 4.2 in the RS6.

The Battery in the RS6 is in the trunk for better weight distribution.

Mike

[JAXRS6]

Originally posted by Nordschleife
The battery in non-US RS6s is in the wheel well.

You're speaking of a front wheel well -- right? Which side?

[Nordschleife]

Originally posted by Aronis
I am sorry, but I refuse to believe the battery needs to be a higher rated battery ie. bigger, simply because it is 8 feet further way from the starter!

No way.



Mike

What you accept is up to you but

Voltage will drop along the cable between the battery and the engine, depending on the current draw and its actual length.

Its not up to you, its Physics.

There is more to a battery than its amperage.

HTH
R+C

[nene]

We're talking about the spare wheel well. You know, where the US cars have a donut that in the RS6 needs a little pumpin'!!!
The battery would still be in the trunk, but it would not be taking the space up top.

I really need a good shop to see if we can come up with some sort of best location to put the battery in.

[Nordschleife]

Nene
Your best bet is to go and talk to a shop which designs Marine Battery systems. There is lots of space if you have freedom of orientation when mounting batteries, you may have to use several different batterires and a custom loom.
There are a few good shipyards in MA/CN/NY. They will be able to point you at the reliable marine electrical fitters.

HTH

R+C

[EternalX]

so why cant you just order the parts for a non-us car and modify it? I dont see why the non-us cars HAVE to put the battery in the trunk, seems like a regulation issue. Especially if the battery in the wheel well seems to work fine for everyone else. is the actual gas tank different in the us version so that it needs a breather? what is the process that is used for non-us cars?
:addict:

[Nordschleife]

Have a look at your car.
The US regulations with respect to charcoal canister breathers, mean that rather a bulky object has to be placed somewhere. The logical place to put it is the centre of the spare wheel well. This does not leave sufficient space to fit a battery, but does allow for a spare wheel to be fitted.
You can buy the parts for a non-US car, but what are you going to do about the charcoal canister intruding into the wheel well.
Placing the battery in the wheel well means that there is nowhere to put the spare wheel - European cars have no spare wheel.
The best solution is to use a number of battery cells in parallel and a custom loom to tuck the battery cells away in the wasted space in the rear wings of the car, or investigate ways of doing this in the front of the car - but don't let them get too hot.


R+C

[Aronis]

Originally posted by Nordschleife
Mike

What you accept is up to you but

Voltage will drop along the cable between the battery and the engine, depending on the current draw and its actual length.

Its not up to you, its Physics.

There is more to a battery than its amperage.

HTH
R+C

Oh My God, your quoting Ohms Law to me, YIKES.

I am an Engineer (BioMedical, Boston University, 1986) and am well aware of the physics involved.

What happens when you JUMP another car with your 20 foot jumper cables? Huh?

The battery is the same size as the 4.2. It does not need to be a higher rated battery simply because of 8 feet or so of big cable! The additional resistance to the flow of electricity over such a distance is hardly measurable.

For example, look at the low voltage used in Computer Networking with RJ 45 jacks via Catagory 5 cable, which allows a maximum range of 1 MILE, that's 5280 feet, not a few meters....a MILE.....thus the drop over a few feet is NOTHING compared to the amperage put out by a car battery!

A battery stores electrical potential - the potential to produce a given current through a given resistance, or to maintain its given voltage when exposed to a given resistance. Thus V=I * R.

The resistance R is a sum of the resistance of the wire (R = resistivity * length / cross sectional area) plus the impedance of the starter motor. The impedance of the starter motor is then affected by the force needed to overcome the compression of the engines cylinders and the friction in that machine.

Thus the component of the resistance of the cable is small in comparison to the impedance of the starter motor.

The resistance in a copper wire is pretty small. The gage used for the starter wire is quite large, I am not sure but the wire is probably at least a quarter of an inch in diameter which would make it 2 gage or so. The resistance per 1000 feet is .1563 ohms, or 0.1563 milli ohms per foot. So you add 7 more feet to the cars starter wire, add about 1.09 milliohms, or 0.00109 ohms.

Not significant.


Mike

[eph94]

Originally posted by Aronis
A battery stores electrical potential - the potential to produce a given current through a given resistance, or to maintain its given voltage when exposed to a given resistance. Thus V=I * R.

The resistance R is a sum of the resistance of the wire (R = resistivity * length / cross sectional area) plus the impedance of the starter motor. The impedance of the starter motor is then affected by the force needed to overcome the compression of the engines cylinders and the friction in that machine.

Thus the component of the resistance of the cable is small in comparison to the impedance of the starter motor.

The resistance in a copper wire is pretty small. The gage used for the starter wire is quite large, I am not sure but the wire is probably at least a quarter of an inch in diameter which would make it 2 gage or so. The resistance per 1000 feet is .1563 ohms, or 0.1563 milli ohms per foot. So you add 7 more feet to the cars starter wire, add about 1.09 milliohms, or 0.00109 ohms.

Not significant.


:brag:

[gjg]

just to have facts correct:


For example, look at the low voltage used in Computer Networking with RJ 45 jacks via Catagory 5 cable, which allows a maximum range of 1 MILE, that's 5280 feet, not a few meters....a MILE.....thus the drop over a few feet is NOTHING compared to the amperage put out by a car battery!

your current flow on ethernet is none comparing with current flow to the car starter - that's where your loss is .........

Ohm's Law

and, since you've mentioned the jumper cables - your alternator compensates for voltage drop due to high current draw ...

George (not arguing the battery size ...)

[Aronis]

Now your getting a bit testy.

What voltage drop are you talking about?

Across a twenty foot cable for jump starting another car? Are you kidding me?

You can jump start a car from another battery sitting on the floor of your garage with those same jumper cables.

Did you not understand the resistance difference of a starter cable over 7 feet, 1 MILLI OHM. MILLI OHM. 1 thousanth of an ohm. Compare that to the impedance of the starter!

The drain on the battery is the STARTER, not the wire connecting it to the Starter!

Let say that the resistance of the wire is significant, just for the sake of argument. So the one foot wire has a resistance of 0.1563 milliohms. So say you increase it by a factor of 8 to 1 milliohm. Further let assume that at worst the motor's resistance is equal to that of the initial .1563 milliohms. So the resistance in the completed circuit is only say .30 MILLIOHMS. Now lets see V = IR, thus V/R = I Current 12 volts devided by 0.30 MILLIOHMS = 12 volts / 0.00030 ohms = 40,000 amps WOW THAT IS ONE HELL OF A BATTERY YIKES. So with the now higher resistance of our 8 foot cable, the battery is called to put out 12 v/0.001 ohms = 12,000 amps, hell that's great! NOT

The reality is the total resistance is the combination of that of the wire and that of the starter. ie. R total = r very little + R a great deal more. More cable length changes it to R total = r very little plus a very little more + R a great deal more....no significant difference.

A typical automotive battery is rated at about 75 amp-hours, ie it can put out 75 amps for one hour.. But in reality they typically put out 3 to 4 amps, and can do it for 20 hours, this is more useful as an energy source since if you do a lot of short distance drives you cannot depend on the Generator recharging the battery if you used the whole load 75 amps every time you started your care.

So lets say 3 amps ...so back calc the resistance of the starter and wire would be 12/3 or 4 ohms, compared to the 1 MILLIOHM added by the longer wire.

Wow now its up to 4.001 ohms.

My example of the VERY LOW CURRENT SYSTEM , Cat 5 wire in an Ethernet, with a functional range of 1 mile, is an example of how little current loss and signal degradation that occurs over such a distance. Now we are talking about a cable that has about 1000 x the cross sectional area and 1000th the length R = rho x l/A.

Enough, this is a waste of my time.

Mike


Hell its all in jest though!
:D

[JAXRS6]

My salesman in Michigan offered to put the battery in the trunk compartment normally used for the spare, but I'd have to give up the spare. I chose to keep things as is because I didn't want to give up the spare. Although I'm not happy with the standard US battery location, I worked around it with minimal problems during a 6000+ mile drive out West last Aug-Sep (2 adults + small dog + luggage for long trip). Meantime, if I head out west again and end up with a flat in some remote area that's many hours away from a dealership -- and there are plenty of those out West -- at least I won't be stranded.

[nene]

Wow....all I asked was for options on putting the battery in some other location, and I can feel all my Electrical Engineering come back in one thread.
Too bad I wasted 100Gs on my education. I could have just used this board, and got the same for free.

You guys are great...that is the full truth! This is one of the coolest boards I frequent.
I really love you all...I know it feels weird coming from another guy, but you guys/gals ROCK!!!

Keep it coming. I will talk to my dealership to see if they have any options on moving the darn box out of the way.

[sturs6]

<a href='http://www.smileycentral.com/?partner=ZSzeb008' target='_blank'><img src='http://smileys.smileycentral.com/cat/12/12_5_49.gif' border=0></a>:dance: Aronis that was nice I liked your explenation.
I wish someone would do the Physics on my Onstar backup battery. I am sorry I just had to throw that in.
:rs6kiss:

[Finnus]

My battery died a couple of months ago. Dead as a doornail. There wasn't even enough power to open the doors with the key-remote.

The first sign something was amiss was when I would start the car, a "growl" would come from one of the speakers (it sounded like it was coming from the pillar between the passenger front and rear doors).

Finnus
:addict:

[Aronis]

2001 A6 4.2 uses 12 V, 450 amp 92 amp-hour battery

2003 A6 4.2 uses 12 V, 450 amp, 95 amp-hour battery

2003 RS 6 uses 12 V, 510 amp, 110 amp-hour battery

The larger battery size is NOT due to location in the trunk, but rather due to more electronic equipment standard in the car. If you get add on's on the A6 4.2, they change the battery to a larger size.

Also, the cranking power needed for the V8 Biturbo is greater - right from the dealers mouth.

By the way, if the added resistance of the 8 feet of wire is an issue, it would be far cheaper to change the cable to a larger gauge- for example if it was as small as 2 gauge used in my example with a resistance of 0.153 milliohms per foot, you could simply change to 0 gauge with much lower restance per foot and end up with the same net resistance of the wire in the trunk vs. under the hood, a clear manufacturing savings!

Mike

:)

[RobertV]

If one were to remove the spare for the battery, would run flats work?
I guess my main input/question is are run flat tires as good as the standard tires yet?
Just a thought

[Aronis]

Good question.

The Run Flats are being used in some sports cars. But with any product that does a range of things, such as all season radial tires, you loose something in the translation.

IE : Snow Tires are still better in the snow and ice than all season radials, and summer performace tires are still better on dry roads than the all season radials.

So run flat's must loose something in terms of performace. They are heavier too so you loose some fuel efficicency.

Mike

[TaTaPiRaTa]

I had 2 weeks holliday without my Beast. When back I couldn't start it :(

I tried to jump it from another car with wires and no way - it was not working.
I had assistance guy to come in with kind of Power Station (a 1400 Amps unit) and it started from first try.

Due to cold winters here I had such problems with many cars before but never was unable to jump start any of them.

RS6 is realy power hungry at start...

:rs6kiss:

[Aronis]

Yes, the battery used is a larger battery than the 4.2 V8 due to higher cranking power need for the higher compression...

This is why the battery is bigger, not simply because it is in the trunk as someone tried to accert in another post....

LOL

Mike