I've now finished putting the battery in the boot, I'm not sure it's made much difference to the handling but access to items under the bonnet is much better now!!

In the kit boot; plastic body so I need to carry the earth forward as well. It doesn't seem to suffer from five metres of 170A (25mm) cable in each leg...

Do you have a link to the red terminal box in the third picture? At the moment I have a 'repurposed' terminal from a dead battery doing the job.

All good until you get a puncture...

A lot of modern cars don't come with a spare these days, just a can of tyre foam.

Really? i bow to your knowledge, but what a completely bonkers idea!

the foam works realy well when you have a blow out at 70 and the tyre comes off the rim lol

Did mine differently, but it's worth the efforts...

I've never been able to carry a spare and so far so good. Worst case I guess I'll have to call the AA if I'm far from home...



Neil, this is what I used if it's of any use to you...

http://www.demon-tweeks.co.uk/Motorsport...Boxes/1451/1294

I got the junction box from the local electrical supplier and painted it red

Junction Box

I've got a kit which includes a pump and replacable foam canister and if that fails AA relay

Just another point, when you do move the battery to the boot, it's a good idea to put a megga fuse as close as you can to the battery, if you do get a short you're covered. I've seen a few of these go up over the years causing exploding batteries and fires

[quote=MrT]



Firstly brilliant work!!

one thing, where did you buy the red and black box things from??
i will do this to mine before Spa!

also, what are you using to keep the battery in place??

Thanks

Marco

This is what i have bought for my track Coupe.
http://www.gt2i-competition.com/BAC_A_BATTERIE_ETANCHE_45AH_55AH-p-11830-c-220_236.html

Thanks, MrT. I haven't included a fuse because to be honest I think the biggest risk is actually something across the terminals... I have a fiberglass body and *at least* two layers of insulation between the poles at all point. Probably not a bad idea, though...

I was thinking of doing the same but, ive been reading that for LHD cars it dosen´t make much difference on handling, is that true?

If it is, i just can`t understand why?.

As I said in an earlier thread, with that solution you WILL risk the paintjob at the back of your Coupe!

At the event acid drops (alternator fail, track day etc.) it will drop on the ground and by turbulence stick at the back and ruin the paint.

Been there, bought the t-shirt.. One thousand small holes meant respray.

Use sealed/gel batteries.


This quote usually comes from people who have'nt tried it yet, but what they meant is: On RHD cars the battery would act as counterweight to the left.. So if you'd put the battery centre rear the car would be more "right-heavy". (But especially, better balanced front-rear).
You could always, as shown above, have it more to the left in the rear.

Here's mine: (never mind the absence of gelbatteries, old pics)
http://sfk.ibk.se/depa/index.php?sub=viewcar&car_no=123

thanks Per.

i thought eswell that it would be better balanced , but like a sayed some people have sayed its not. just wanted to confirm.

thanks for the pics very helpfull!!

[quote=Per]As I said in an earlier thread, with that solution you WILL risk the paintjob at the back of your Coupe!

At the event acid drops (alternator fail, track day etc.) it will drop on the ground and by turbulence stick at the back and ruin the paint.

Been there, bought the t-shirt.. One thousand small holes meant respray.

Use sealed/gel batteries.

Hi Per

That's why I've put mine in a battery box with a breather tube fitted, any spillage is contained in the box

Hi Marco

Thanks mate.
The red box is a battery box form fleabay or any racing supplier and the little black box is the 250amp megga fuse. The battery sits on a foam pad and is wedged at the sides with hard foam strips, once the top is bolted on it's all sealed nice and tight.

ahve you got a link??

Also, would a sub/amp fuse be man enough to man enough to coupe with this?

im removing the sub from my car and i have the power cable in place already..

so all i would need to get is just a tray like yours and the engine side connector!

i cant remember what fuse i have in place already...

the power cable is 0.1 gauge i think and the earth is a 0 gauge!
chunky!!!

Ah I see, good.

Marco, the fattest cable you can get. The starter stalls at around four or five hundred amps...

I've used 170A cable for both go and return; that's 25 square millimetre and probably the heaviest you can get. If I fuse it it will probably be at 250 or 300 hundred amps (because the I think cable is overdriven during starting - not a problem because it's for only a few seconds).

Your amp cable may work once or twice but is not man enough for regular use.

This thread has caught my interest. I am not so bothered by the arguament of weight distribution as my car often is carrying extra weight in the boot etc.

However the thought of clearing the tray and battery out the way is very appealing.

Neil....
your talking spanish again...

all i understand from that is, my cable is bad/ not man enough... i need a new cable and a big fuse for this...

what cable shall i look for then??

i cant be bothered to work today so im going to get this ordered and sent to me before the car is back from re-spray.

Marco get a 25mm seccion cable of a 170 amp, bought mine yestuday on ebay.

how long does the cable need to be??

and is this what i need??

yep marco, thats correct! I bought the one of 3.95 a meter.
Thats perfect 170amp and 25 mm seccion.

You need approx 4m of cable from the bulkhead to the boot, maybe a little more

i may get 5m, end of the day i can always chop it down!

can i use the .0 gauge earth cable still??

...depends of the amp cable you have, in the old volvo I had, the amp cable was fatter than the batt one. If so concerned go for 50mm2, the phisical difference (diameter) is minimal compared to 35mm2, the price diff also, they are around 4Eur and 3,5Eur respectively. There are also protective sleeves cheap enough. Better place to get (price-wise) is big store for electric material or big i-net/ibay supplier.
Reference here, bootom of the page , though not covering the european standarts.

You'll need to use the same fatness cable to connect your battery to the earth in the boot - the same current flows in both.

giggady..

Neil, i may call you as i have a wiring idea!!

Neil sorry for my ignorance, but you mean that the earth cable that you need to use is the same one?

Wherever the battery is in the car, all the current that flows *out* of it also has to flow back *into* it - conventionally we think of current as flowing from the positive to the negative terminal.

The significant current draw is during starting; this can be several hundred amps. If the cable is not rated for that current, it will get hot and potentially melt its sheath; that leads to a short circuit to a convenient earth (usually the chassis) and that leads to massive currents, massive heat, and fire - because the lead acid cell has a very low internal resistance.

So, the positive wire has to be fat enough to pass the necessary current without heating. The negative wire returns usually through the chassis, but has to connect to it somewhere - that wire has to carry the same current as the positive, so it should be as thick...



So, yes...

btw - the alternator can supply well over 100A on aircon models, so after a few seconds of very high current starting, there could be several minutes of high current going the other way to charge the battery. However, most high currents on the positive side - alternator to aircon, fan, and lights, circulate to the main fuse box which remains at the front of the car. It's really only starting and charging currents which are of concern here.

(A secondary effect is the voltage drop across the resistance of the wire. You want that as low as possible, hence as thick a wire as possible. On my kit I have to run both the positive and negative from the back to the front since I have no chassis to carry the ground; the fiat wiring shows many earths but they all expect to pick up an earth from the chassis - that is, they're providing an earth path *to* the chassis from the various lights and whathaveyous. The chassis is clamped very close to the battery on the coupe loom and can be considered to be a very low impedance path back to the battery.)

so then you actually don't recomend connecting battery negative to the boot? as you say "you have to run both the positive and negative from the back to the front since I have no chassis to carry the ground".
would this problem be soolved by getting a larger seccion cable like insted of 25mm a 35mm ?

I have only the pos.cable to the front, absolutely no problems at all. Saves weight too.

Nah - on the coupe, there's all that metal chassis convenient to hand - a big bolt (m6 at least) through a proper tag and with a star washer to cut through the paintwork. You'll be fine then and you only need a foot of 25mm cable to connect it.

I have to take the negative forward because my kit has a non-conductive load-bearing fibreglass bodyshell, no chassis.

cheer Per.
Forgot about that Neil.

Haven't had time to finish this mod as im needing also tu buy the fuse box. As I see, I should go for the 250amp fuse, but can i fit a 200amp fuse or is it very little? I have one in my garage and its to not buy another one.

Cheers

See if you can get the wire from a gtv breaker as they have it back there as standard and possibly workout cheaper then buying new and having to get new terminals etc etc.

im going to be doing the same to my coupe but i think the most advantage is the mount of space it frees up in the engine bay which im after more than anything

Be aware that if you move the battery to the rear of the car, you will get a larger voltage drop due to the internal resistance of the copper cable being over a longer run. In other words, copper cable will drop x volts per metre due to its internal resistance. The longer the cable the greater the voltage drop. I would suggest a thicker cable be used for your new cable run to the battery in the rear than you currently have in the front.
Have a look at this site www.stealth316.com/2-wire-resistance.htm to see what your V drop is for a given length and diameter cable.
All this means is that you will get the amps you need to turn your starter motor properly and the fatter cable will reduce the build up of heat in the cable and hence less risk of a melted sheath or worse still ... fire.

I am in the process of doing the exact same thing in my Stag

Cheers

you dont have to make calculations you put a cable from an alfa 164 that has the battery in the boot no problems or calculations its been done in alfas from factory

I tried starting my coupe with a battery in the boot running through an amp cable, wouldn't even kick, with a new battery. So leave the amp cables alone in my opinion

Forget amplifier power cables. 25sqmm works fine with five metres of cable on my kit with the 20vt engine.

The point I was making was that you will need larger diameter cable to the battery in the back than what you may already have to the battery in the front due to higher resistance in the copper cables.
What is an amplifier cable going to do unless it is a fatter cable?

Quite. You also need to consider the power dissipation in the cable, which is proportional to the resistance and the current flowing. An amplifier cable *looks* fat in comparison to other wires in the car, but is probably rated at no more than 40A peak, probably half that continuous rating, and the makers have been known to make them *look* bigger with thicker insulation...

This would also make it easy to run a seperate power to the fuel pump, like 2 birds with one stone this one! Well maybe 3 or 4 actualy..

Weight distribution
Engine bay access
Fuel pump mod
.......

Yepp!

just going through this thread i have done what is wanted here after lots of testing ... i use a red top battery which is a gel and sealed so it can be put in any position i know its not on a coupe that i have fitted the battery to but i know it works with no problems
1 get the thickest battery cable you can within reason if you have aircon the bigger the better
2 with a red top you could mount the battery on the bulkhead behind the back seats as high as you can or behind the side fittings (carpet)
3 this is the big one put in a earth cable to the body in the boot and you most run a earth cable from the battery to the engine. i dont care what people say the earth works .... i get better cranking with the earth every time
this is what i have done on my bro's celica st185 track car
http://i1129.photobucket.com/albums/m508/louieuk/st185/P1080003.jpg
http://i1129.photobucket.com/albums/m508/louieuk/st185/P1080005.jpg

and you can do the fuel pump mod

One other benefit is of course you can put the battery much lower than std position; in the sparewell.
So I disagree with putting the battery high up and the need of a thick heavy long earth cable.

the thing with a sealed gel battery is it can be put anywere in the car and it weigh's a lot less than a lead acid battery about 1/3 the weight
Per the reason i was saying put it high up in the boot is because the wheel well and boot can still be used...... as for the earth you dont need to put a large cable in as long as the battery is earthed in the boot as well i just found that having a earth running from back to front gave a lot better cranking over power

Hi guys, any follow up on this mods? Curious, what model of battery do you guys use? The stock in Malaysia is Din55, but some mechanic recommends Din66. do you use the same calling name? Thanks

I use twin gel MC batteries, 2 x 18Ah. Quite cheap around here (ca 75euro each).
Looks like below.

Also, putting an extra earthing strap between engine and body sorted out the last cranking issues. No need to run a full lenght earth cable!

http://sfk.ibk.se/forum/showthread.php?5311-Coupe-projekt-batteriflytt/page5