Battery Relocation

[Rams_gti6 12 1 Cars]

Thinking of moving my battery to the boot to free up some space under the bonnet, how do I go about joining the positive cable to the new cable to run it to the boot or do I have to renew the whole thing? The earth can be strapped to the rear beam bolts?

[Slo 283 1 Cars]

Go to a scrapyard that you can actually walk round and gut a bmw for it's battery leads that has the battery in the boot, the cable will be nice and thick and the ends formed (similar to 205 originals ones) to fit on the battery.

 

I don't know if all bmw's are like this but I got mine from a newer convertible that had a box mounted in the engine bay that it went to and the engine ancillaries bolted to it, bonus advantage is it has a jump lead terminal on the top for flat battery episodes.

 

Earth lead can be bolted to anything in the boot.

[unariciflocos 49 1 Cars]

Or you can just buy 30sqmm stranded copper cable with rubber (NOT plastic) insulation and some ring lugs. There should be a small fuse box under the bonnet where you can hook it up to an M6 stud I believe.

 

I've always had trouble with the ground connected to the body, so this year I also hooked up the ground via a cable all the way to the starter.

 

Lenghtwise you'll need about 4m for each.

[td_w 2]

Hey everyone, hopefully not hi-jacking this thread but I am going to put my battery in the boot area. I would also like to have a light, sealed race battery.

 

Does anyone have any recommendations on battery to use, or not use?

 

Also, I want to wire up a kill switch on the dash. As I understand it this needs to also be wired into the alternator and ignition to actually work. I think I can work it out but wondered if anyone had any helpful hints or photos of installing these switches?

 

I will probably bolt a battery holder to the boot floor, or even weld it depending on what battery works best.

 

I don't have any interior so it should be pretty easy, I hope.

[td_w 2]

*bump* any help with the above gratefully received. Cheers

[Dizzee stuff 33 1 Cars]

When I have done it in the past I used welding cable

[dobboy 231 2 Cars]

"Tri Rated" cable is the really fine stranded flexible stuff.

 

Edmunson elec, or Batt or Cleveland cables may be able to get you it, but u may need to buy a drum of it.

 

Or, you could ask an electrical switchgear/control panel builder.

[dobboy 231 2 Cars]

When I have done it in the past I used welding cable

That stuff might be called EPR cable

[td_w 2]

Thanks for that. What do I do with the old live and negative cables under the bonnet. Can I connect the negative to the bodywork? Can I just put a connector on the old live cable end and connect to my new cable from the boot area?

 

Thanks in advance

[Miles 331 1 Cars]

I always use Rep Top's battery wise,

Cable, remove all the old positive cable and make new, Battery to Starter, Link cable from starter to alt and Shunt box, The junction box idea is a quick fix really and just add's joins/connections into it.

I'd make new Earth cables too

[eastlondonpug 6]

 

Miles, I have been trying to contact you since a long time, can you kindly check your inbox I have pmd you several times.

 

Thank you

[petert 554]

Just remember to place the battery forward of the rear axle(s). Behind that is detrimental to handling. There are heaps of quality, low mass batteries available now. They may cost a few dollars but well worth it in weight and space reduction.

[Dizzee stuff 33 1 Cars]

The welding cable worked out cheaper than battery cable at the time

[dobboy 231 2 Cars]

This is the cable i would use (as an electrical engineer, not a mechanic)

 

http://www.batt.co.uk/products/view/679/Tri-rated-Panel-Wiring-105degC-BS6231

 

Not sure if they would sell you a few metre's though.

 

 

If you don't want to renew the mains at the starter/alt etc, and prefererred to joint, for joints i'd use a thing called a mechanical connector (shear off), which allows you to "through joint" two different sizes of cables (and multiple cables). That way you won't need a hydraulic crimping tool, with a bit of medium wall heatshrink tubing over it to insulate it (or you could use self amalgamating tape). I probably have a couple of shear off's if you struggled to get them.

 

For the neg you squeeze a lug on the end of the existing, bolt it to earth, and run a new neg from the same bolt to the battery.

 

 

Is the "cut out" you mentioned a contactor/relay on the battery mains wires (operated by a push button/switch) or a heavy duty double pole switch on the mains?, or a switch on the ignition somewhere?

[td_w 2]

Thanks everyone, appreciate the help. Really useful.

 

Thinking I might put battery just behind the handbrake area, the red top i am looking at is only 6.5kg too. Any issues with locating it there?

 

@dobboy thanks for the help, the switch is something like this: here and I found this handy wiring diagram here but still looks a little tricky.

 

@Miles thanks for that - sorry to be dim but what is the shunt?

 

Thanks in advance

[Ryan 99]

The shunt box is the small fusebox on the slam panel. It's normally connected straight to the positive terminal on the battery, and from there it feeds power to the fan, and to the main fusebox under the dash.

[dobboy 231 2 Cars]

Thanks everyone, appreciate the help. Really useful.

 

Thinking I might put battery just behind the handbrake area, the red top i am looking at is only 6.5kg too. Any issues with locating it there?

 

@dobboy thanks for the help, the switch is something like this: here and I found this handy wiring diagram here but still looks a little tricky.

 

@Miles thanks for that - sorry to be dim but what is the shunt?

 

Thanks in advance

 

Oh i see, it's just a double pole rotary switch, 1-pole beaks main battery feed, the other pole (aux contacts) breaks ignition.

 

That shouldn't be too bad to wire up at all.

[jackherer 543]

It needs to ground the alternator output via a high current resistor when it is turned off too. There are both NC and NO contacts to allow this. If you don't fit a resistor the alternator output spikes when the battery is disconnected.

 

[Tom Fenton 1,526]

I have a red top type battery mounted in the rear footwell, as low as possible.

[td_w 2]

Nice one, thanks for all the help, going to give it a go Saturday

[td_w 2]

Ok just so I am totally sure here

 

I can connect the existing battery negative cable to earth and then bolt the new negative cable from new battery to that same point of earth? Any tips on where to bolt it to?

[unariciflocos 49 1 Cars]

Not sure I understand your question, but here's my setup (i build large scale solar power plants).

 

My battery sits in a box in the rear passenger footwell with soft rubber insulated 35mmsq stranded copper wire going to the engine. Plastic insulated cables are cheaper but a real pain. You'll want to use copper wire as much as possible to your engine, starter, coils, etc both for live and ground. I'd avoid using the body of the car as an earth as it can be quite noisy, steel will have a higher resistance and connections have better chances of corroding and becoming hot spots.

[Tom Fenton 1,526]

I don't think the comment about earth really holds true in 12v DC automotive. Many many OE production cars have batteries rear mounted and earthed direct to the body near the battery. For e.g. Minis and MINIS, many BMW's etc.

[welshpug 1,626]

yep, you cant get a lot further from the alternator thsn a 7 series with a rear quarter corner housed battery!

[unariciflocos 49 1 Cars]

It's definitely not a must, but it will help and better to do it once and do it right.

 

You'll have to remember that as with any industry everything is driven by cost, i hear the words cost reduction 100 times a day at my job and with copper at an all time high, at the end of the day it's a compromise.