# Battery relocation to boot advice



## fixitagaintomoz (Apr 26, 2013)

Hi guys, thinking about moving the battery to the boot. Reason being I want space in the bay for a catch can and a wmi tank ( in the future) and the space under the battery cover will be really neat and tidy.

I have a couple of questions. Who supplies a shallower battery than stock, that will fit in the spare wheel well without modifying the floor. I don't want a race battery or a lightweight one, as weight isn't the real issue and sending some to the rear isn't exactly a bad thing.

What gauge cable shall I go with for the run to the front? I know there will be a slight voltage drop, and the bigger I go the lower the resistance and therefore the better, but I don't want to go overkill.

Mounting wise I have a plan to have 2 straps- one side to side and one back to front, bolted to the floor. Simple but functional.

Any pics of people's relocations? I've seen them where the car is stripped but I want to be using the boot floor still.


----------



## fixitagaintomoz (Apr 26, 2013)

Surely someone else on here has done this before? Or is this just a step too far from a lowering/thermostat/dash pod/alloy/spacing/haldex/dv/air filter/vac leak question for anyone to know the answer?


----------



## Wak (May 6, 2002)

fixitagaintomoz said:


> Surely someone else on here has done this before? Or is this just a step too far from a lowering/thermostat/dash pod/alloy/spacing/haldex/dv/air filter/vac leak question for anyone to know the answer?


Patience! :lol:


----------



## fixitagaintomoz (Apr 26, 2013)

So 100a was the highest draw, so find a cable capable of 120a to be sure


----------



## Wak (May 6, 2002)

I've just done a split charge and twin battery setup because of a long term battery drain issue but you may consider my solution overkill.

I ran a 415amp cable front to rear and have 300amp fuses at both ends. The cable size is to give the best transport and to offer minimal voltage drop.

I'm running a standard battery in typical boat/caravan auxiliary box luggage strapped to the boot floor. ( I don't have or need much boot space.)

I think if you intend to run a smaller battery your cranking amps vary, some more or less but usually the amp/hours will be less hence minimal voltage drop is desirable.

Are you certain your car is healthy for leaving it a few weeks and it would start, going for a smaller size unless you can get smaller size with similar or more capacity, could limit how many days you can leave the car.

Combined with the increase in alternator output I got from another mod, I'm seeing healthier battery levels but I honestly haven't taken the risk of leaving the car a week to see what happens yet for my dual setup.

Anyway the point is I'd recommend a good size cable and fuse holders either end.


----------



## Wak (May 6, 2002)

fixitagaintomoz said:


> So 100a was the highest draw, so find a cable capable of 120a to be sure


no, 100a was the highest draw in that quick test from the alternator and that's distributed from the fuse board above the battery to internals, engine electrics , abs, fans etc to run the car.

Starting current is likely to spike higher than that, its unclear what that may be unless someone has the kit to measure that. 
I would say 150-200a with a free engine, try to start it in gear by accident and maybe up to 250-300 could be demanded? ( just guessing) but you should get a good cable front to rear.

My setup still has the starter battery up front but the cable size is there to cope with the fateful day the starter battery is dead and it can cope with starting from the boot.

I wouldn't go anything less than 300amp cable, but ideally be nice to know for certain what starter current can draw.

Theres a lot more to cable as well but basically:-

X-section area sets the current handling.

Many stranded cable is easier to manipulate in bends and trunking/ routing through the car but can suffer higher voltage drop than cable with thicker strands for the same cross sectional area.

Less stranded cable has less voltage drop which is better but at the expense of being stiffer and harder to manipulate around tight bends and curves that may be involved in routing.


----------



## conlechi (May 6, 2006)

APS relocated my battery to the boot of my old TT , an Odyssy battery was used , compact and fitted under the boot floor , and oem QS cables from the front to rear of the car 

[


----------



## fixitagaintomoz (Apr 26, 2013)

Thanks for the responses, so the odyssey battery fits ok without modification? That's the one then! I've seen some 340 amp rated cable so that will be what I go with.

Wak 2 batteries is just greedy!


----------



## Lollypop86 (Oct 26, 2013)

fixitagaintomoz said:


> Wak 2 batteries is just greedy!


He doesnt do anything by half you should know that lol

J
xx


----------



## Wak (May 6, 2002)

conlechi said:


> APS relocated my battery to the boot of my old TT , an Odyssy battery was used , compact and fitted under the boot floor , and oem QS cables from the front to rear of the car
> 
> [


That looks like two positive feeds disappearing off into the body work... one fused and one unfused? 
what's happening there?


----------



## Kyle18uk (Jul 3, 2012)

I have a a QS battery cable for sale if you need it?

I've just relocated mine into the boot using 6m of 50mm welding cable, one cable from starter to boot battery, a smaller cable from starter to fuse box on top of battery then using the 50mm a small earth from battery into boot

I bought a proper crimping tool from ebay which makes a really nice join to the terminals

Cable - 
http://www.ebay.co.uk/itm/310711849275





I mounted my Odyssey PC680 to the rear of the boot then cut the boot panel around it so it just sticks out, looks very neat


----------



## Wak (May 6, 2002)

I don't see a nearby fuse from your +ve terminal to protect that cable to the front.

Also if you measure those terminals and they have, for example, 15mm diameter, you can buy a short piece of 14mm silicone hose and cut some small pieces to slide over them to provide some protection from accidentally touching them.

I did this for mine..


----------



## Mondo (Feb 20, 2009)

Mark, I think this is the 2nd picture you meant to post:



Damn, giving me ideas for my WMI install in the summer.


----------



## cookbot (Apr 19, 2011)

I've got a QS relocation cable on the cheap and was wondering wha the getup is with it's connections. It's not arrived yet, so can really have a good look, but it seems it has 2 positive lines, one fused and one unfused. The other end has 1 connection I assume is for the started (with 2 holes) and the other I assume goes to the fuse board. Can the earth from the front of the car just be relocated to the back and bolted securely to the shell?


----------



## Jez xbx (Oct 24, 2014)

at the risk of mentioning the unmentionable!
From memory my mk 2 had a battery in the boot?
You could see if you can find out the cable size they use for that?


----------



## Von Twinzig (Feb 10, 2014)

Guys, can someone with the cables weigh them when you get a minute please? I've got the odyssey mounted up front, but would only move it if the weight made sense.

Thanks

VT


----------



## katak (Jan 26, 2010)

Hello All,

Is there any tutorial with picture that reall yshow where wires go and come ? : )
Both + / - wires need to be relocated in the trunk ?

Thanks in advance,

Pascal


----------



## kraftwerkturbo (Dec 26, 2016)

katak said:


> Is there any tutorial with picture that reall yshow where wires go and come ? : )
> /quote]
> 
> Same here: where to run those fat 50mm2 or 60mm2 cables?
> ...


----------



## David C (Apr 15, 2013)

kraftwerkturbo said:


> Perceivable to go OUT the well and run UNDERNEATH the floor to front? Risk of damage/short?
> Can't see how the fat cable can be tucked under the (driver side) door sill.


Run the cables along the sill inside the car, exactly like Audi did with the V6 & QS.

DO NOT run the cables under the car...!!


----------



## StuartDB (Feb 10, 2018)

Old thread I know, but for clarification..
1. Only need a +12v going to front of car, and -12v to chassis post like the Haldex earth strap?
2. Is it just a matter of connecting the +12v to the fuse box?


----------



## David C (Apr 15, 2013)

StuartDB said:


> Old thread I know, but for clarification..
> 1. Only need a +12v going to front of car, and -12v to chassis post like the Haldex earth strap?
> 2. Is it just a matter of connecting the +12v to the fuse box?


On the V6 & QS there are two big cables to the front.
a big cable with +12V to the fuse box and another big +12V cable to (I think) the starter motor.

As for the chassis connection, that isn't -12V, it is 0V.
(Petty I know, but +12V and -12V = 24V ...!)

The chassis connection is straight to the bodyshell next to the battery.


----------



## StuartDB (Feb 10, 2018)

Thanks, it's weird batteries still have a - sign for negative, when it's really ground.

I'm thinking about sourcing from camper, boat, caravan type of suppliers. I don't imagine it will be cheap though.

10m enough?


----------



## StuartDB (Feb 10, 2018)

Another quick query but should I be aiming at 50mm2 or 70mm2. I think it is rated about 345amp or 400amp respectively.


----------



## imartyn (Aug 31, 2015)

There's a V6 cable on Ebay UK for probably adout the same as the cost to make one...search 8N0971227


----------



## StuartDB (Feb 10, 2018)

Oh that's great thanks.. do you know if the Haynes manual shows the exact route as obviously that cable must fit the same way?


----------



## imartyn (Aug 31, 2015)

Et voila......https://www.ttforum.co.uk/forum/viewtop ... 2&t=130078

Haynes doesn't cover the V6 or QS :x


----------



## StuartDB (Feb 10, 2018)

That's amazing, thanks for digging that out 

So on a QS / V6 is the fuse box mounted onto anything?


----------



## David C (Apr 15, 2013)

StuartDB said:


> So on a QS / V6 is the fuse box mounted onto anything?


Yes it is mounted in the same place as a "normal" 1.8T


----------



## StuartDB (Feb 10, 2018)

Thanks David, hopefully once relocated I will be able to fit the 63mm map sensor pipe and 4 bar map sensor  and get rid of the water meth pump tie wraps.

I picked up the ebay V6 boot cable - that would probably have been cheaper 85 euros delivered - I doubt I would have managed that buying new, so thanks again for posting the link Martyn.


----------



## StuartDB (Feb 10, 2018)

Not bad for £76  (including the postage from Germany too)


----------

