battery relocation!

[crpvrs]

hi all,

 

i plan on putting my battery in the boot of my vrs to tidy up the bay a bit better, 

 

does anyone have any idea what gauge of cable ill need to run the positive to the fuses which will stay in the engine bay,

 

many thanks,

 

Callum Peacock

[VWD]

No idea, but perhaps it might be an idea to start looking at the cable twixt starter and battery and loss per foot, at starting current. Ideally you want little or no loss to the starter ,so it might be an idea ,when relocating battery with heavier cable, to upgrade the battery box- starter cable. Problem is how do you run it, as there's no /little access through firewall into passenger cabin, so only other route is under car. Alternatively, get hold of an auto ranging ( possibly withhold function) DVM and measure drop from battery in box to starter, and use that drp as a starting point from rear battery to starter, then get cable resistance cables at starter current and work from there ( hint- volt drop = cable resistance *starting current), but it's a lot easier to measure the volt drop. Just my ramblings, as it's possibly a god idea.

[SKYHAWK]

also interested in this if it looks neat enough

[giandougl]

Battery was in the boot of my old mini-car, with power starter cable running under the floor pan, and being earthed to the floor rear of car.

But the mini was short-in-length body in comparison to the Fabia..

[crpvrs]

seen it done before,

 

but the lad just had his ratchet strapped to the luggage hook in the boot. and isnt to sure on the gauge of his wire,

 

the 0v line will just be attached to the boot floor in the wheel well, and painted with liquid electrical tape.

 

have a multimeter and current clamp so can measure the starting current on the cable and the voltage drop.

 

i am a electrical engineer by trade but car electrics confuse the hell out of me

[PoloGTimposter]

I have been thinking about doing this as well,

I was thinking about using a thick gauge of wire that you can get in the wiring kits for amps and subs etc. As an extra fuse close to battery would be a good idea in my eyes just in case the cable was to be cut or sliced in an accident or something.

Can't see the resistance of the cable run affecting anything unless you were going over 10meters which shouldn't be a problem with these cars.

On paper it sounds like a simple job but from previous experience with other cars getting the cable from the boot to the bay is usually a *******!

[Phil-J]

I wouldn't use the wiring out of an amp kit personally, just out of experience.

Use the best quality wire you can get hold of too.

[crpvrs]

i was planning on using marine grade wire,

 

standard battery for the vrs has a CCA of around 700 amps,

 

75mm marine cable has a current carrying capacity of around 500amps will this suffice?

 

CCA is measured at 0 degrees farenheit

the battery only produces a high current for a few seconds doesnt it?

 

there is 100mm cable to,

 

putting a fuse in will be a nightmare a fuse with a 700amp rating would be huge!

[PoloGTimposter]

We would need to find out how much current the starter motor would draw from the battery and then work out the best cable.

If it was 700amps and you were using a 500amp cable even if it was only drawing current for a few seconds surely it would over heat and bust into flames. 200amps is a hell of a lot of current!

[crpvrs]

http://www.briskoda.net/forums/topic/275124-moving-battery-to-boot/

 

so after reading this, it says 35mm will suffice,

 

so ill go for 50mm to be on the safe side,

fuse and fuse holder i will use,

http://www.shop.sterling-power.com/acatalog/ANL_fuses.html

http://www.asap-supplies.com/marine/fuse-holders-and-boxes/anl-fuse-holder-729342

 

will make a battery tray out of somethign as well to hide it away

[devonutopia]

I used marine grade 4awg. Halfords equivalent not near as good.

[crpvrs]

I used marine grade 4awg. Halfords equivalent not near as good.

had planned on using high quality cable,

 

can get stuff from work that is used to start v10 diesel generators drawing about 800amps on start up,

but weighs a fair bit and cant get it off on the chopper!:(

[Breezy_Pete]

Something to be wary of is that a relocated battery that isn't well secured mechanically could become a lethal missile in the event of a crash. Imagine having a car battery thrown at you when you are working out how to secure it.

[PoloGTimposter]

http://www.briskoda.net/forums/topic/275124-moving-battery-to-boot/

 

so after reading this, it says 35mm will suffice,

 

so ill go for 50mm to be on the safe side,

fuse and fuse holder i will use,

http://www.shop.sterling-power.com/acatalog/ANL_fuses.html

http://www.asap-supplies.com/marine/fuse-holders-and-boxes/anl-fuse-holder-729342

 

will make a battery tray out of somethign as well to hide it away

Sounds like a plan to me matey, do you fancy doing a how to guide to make my life easier - cheeky I know :-D

[PoloGTimposter]

Something to be wary of is that a relocated battery that isn't well secured mechanically could become a lethal missile in the event of a crash. Imagine having a car battery thrown at you when you are working out how to secure it.

Agreed wouldn't take much of a bumpy ride to throw an unsecured one through the parcel shelf and in the cabin or out the back window.

Something like this should do the trick I reckon

http://www.butserrubber.com/products/straps/

[devonutopia]

Something to be wary of is that a relocated battery that isn't well secured mechanically could become a lethal missile in the event of a crash. Imagine having a car battery thrown at you when you are working out how to secure it.

 

Mine is clamped and bolted right through the floor of the spare wheel well, in three places.

[Taylor93]

Is Marine grade cable you are using Aluminium wire or Copper?

 

size for size, Aluminium wire is 1/4 the weight of Copper cable. but the Aluminium is twice as resistive.

 

So if space isnt an issue, you can use twice the Cross sectional Area (to overcome the double of resistance) which will be half the weight as the equivalent current handling copper cable.

 

its the ultimate weight saving

[SKYHAWK]

Mine is clamped and bolted right through the floor of the spare wheel well, in three places.

pictures if you got em m8

[crpvrs]

Something to be wary of is that a relocated battery that isn't well secured mechanically could become a lethal missile in the event of a crash. Imagine having a car battery thrown at you when you are working out how to secure it.

 

it will be held secuerly motst likely be well over engineered 

[hutchysrs50]

Get the cable ties out!