Evening guys, going to be relocating battery to rear of car, running cables from battery to original position through car, would you put a fuse next to battery and if so what sort of current rating?

Cheers jason

 

I'm also planning on doing this. Are you creating a bracket for it in trunk or something?

Also I think you only need to run a fat + lead from battery to original location. GND is ok if you connect to chassis in the back.

About the fuse - I wouldn't bother at all, nothing changes, only it's physical position, so factory fuses should keep on doing their job.

 

Its going near where the rear seat used to be, i was thinking about putting a fused battery post clamp as not too keen on running the power from the battery through the car without fusing as if it got caught on body somewhere it would catch fire

 

fuse the new cable as close to the battery as possible

the fuse is there to protect against cable damage, and the fuse rating should thus be selected based on the cable rating used

 

when i did mine nearly 20yrs ago i ran a seperate fused cable to feed just the fuse box, and a second larger cable to the starter via a mini starter solonoid. meaning the starter cable was only powered whilst cranking. i hid a button under the steering cowl to the mini solonoid and the key still operated the starter.
i did it this way because i had loads of old stereo shit left over, and i was skint.

have you thought about a circuit breaker rather than a fuse. less hassle if its needed.

 

I going to be doing this as my breather system is fitted in my battery tray now. I don't like the idea of a live cable running from back to front under the carpet. If it rubs through it will dead short and set fire to the carpet. Problem you have is it will need to be a large fuse because of the starter amp draw other wise it will keep blowing. The problem is with a large fuse and a good size live cable is you could have a small short that's not going to blow the fuse but could still get hot enough to set fire to the carpet! I'm just going to get a good quality cable and run it inside a flexi wire conduit

 

The problem is finding a fuse that will allow the engine to start...ie starter can draw several hundred amps, but actually blow when there is a fault like a short...which may actually draw less than starting the engine depending on severity of that short.


If you must run a fuse, run 2.

One on a dedicated line to the starter only, and then another for all the other devices that may need powered.

Also bare in mind, that once the engine is running all power is provided by the alternator and any excess charges the battery. So actual current draw on any accessory line once running probably wont be that large.

But run the large battery cables somewhere safe and less likely to get damaged in any impact and there should be almost no risk.

 

Im thinking, to run cable through flexi conduit and prob no fuse, also i assume i can earth the chassis near the battery instead of running a separate earth all the way to the front

 

Any suitanle cable will have good thick insulation anyway ( ie welding cable ), but conduit where it passes through metalwork would be an idea.

Conduit elsewhere...debatable. At least bare insulation you can easily visually check for damage. With an outer sheath whilst it may appear ok, isnt always the case. Plus the conduit will add physical size.

And yes, just ground the battery local to a good clean bare metal part of the chassis.

 

Thanks for your advice, great help

 

If you do fuse the main cable 150amp will be fine I've amp draw tested a few 12v vans at work now and there around the 160-180 mark so a yb will be fine with 150 I'd say

 

That's what I did when I did the re wire for my Lion Battery.

Rich

 

This is what I did on mine https://passionford.com/forum/restor...rbo-zvh-7.html

 

when i did my evo i used a cable from a scrapyard bmw,e46 m3,got the full cable with the junction box for the enginebay

also got the earth strap for in the boot,but it will change it to round post conections,these did not come with fuses from factory only latest ones have fuse

 

When I moved the battery to the back of a Mk2 Escort estate I had to run a separate earth cable to the front of the car as it was very slow to crank over.


I think the combination of old steel joined together with old spot welds gave too much electrical resistance.


With the earth cable it was spot on

 

Im going to do the same on mine! A poor earth can lead to all sorts of problems

 

We do this all the time...we either relocate batteries or install additional battery/ies to other parts of the vehicle.

What you need is the following;

Good quality OFC 50mm2 (0gauge) cable from front to back for the positive
You can add either 1 or 2 fuses depending on how safe you want to be...1 fuse as close to the battery as possible is sufficient. If you want to add two, you can add 1 near the front bulkhead
With the earth, as stated above, you can uprate the front earthing points to 0g cable as well - uprate the engine to chassis cable as well. Or you can run a new 0g cable from the battery direct to an earthing point in the engine bay. As well as this, I would also earth out the rear battery to the chassis right next to it.

Ill be doing the same into an Orion soon, and the plan for that is to put the battery in the boot, extend the current cables from the engine bay area to the boot. Run 2 0g positive cables from battery to engine bay...one going direct to the alternator, and one going to the starter. A third 4g cable run will be made to connect all the cables that will normally run to the car loom. A 0g earth will go from battery to chassis point in engine bay, uprated engine to chassis earth, and the battery will be grounded to a earth point in the boot.

If you need any help or info...just drop me a PM

 

35mm^2 welding cable is more than enough for the starter on any vehicle.

Smaller engines like Cossie etc, 25mm^2 would be fine

And again, the alrge cable is primarily to handle starting current only. Once the engine is running, ALL vehicle power is coming from the alternator anyway. If it wasnt, your battery would be discharging.

 

I agree...but welding cable in my experience is terrible to work with compared to proper audio cables from the likes of Knu Konceptz and Sky High cables. 35mm welding cable is also not a proper 2AWG (2g) size....when we compared 70mm welding cable, it was more inline with 50mm2 (0g) true gauge power cable from the manufacturers above.

Welding cable will work yes, but im not a fan of it, its not the best to work with.

With the audio cables we usually use, its ALOT easier to get into tight corners and the sheathing is alot more automotive friendly.

Using a true gauge cable in OFC, 4g will probably be ok, but over that distance of a few meters, I would say use 35mm2 (2g)...but 2g is car audio applications isnt stocked by many people, hence the reason for using 0g.

My Previa ran 20 XS Power 14v batteries in the back and 3 300amp alternators...power cable running front to back to run the vehicle was 0g OFC true gauge (5600 or something strands).

Knu Konceptz and Sky High 0g cable is able to handle 300amps of current over 5m...shorter runs will obviously handle more. 4g KK or Sky High will be able to handle approx 175amps (both OFC cable)

 

I presume you're referring to powering huge sound systems though, with sustained heavy loads from the battery because of the alternators struggle to supply power on demand.

Not the same as a normal car or even a heavy use race car.

I've never used the cable you refer to, but welding cable is very flexible and has good think insulation. I find it ideal

Not sure what way you are comparing size for size etc ? 35mm^2 is conductor size only, not outer sheath etc and as I'm sure you are aware, proper multistranded cables can carry much higher loads than less strands with thicker strands

But using 50mm etc on a car is just insane unless it is for something as dedicated as a huge sound system

The only time a normal car sees very heavy current draw is during cranking. No other time.

 

any chance of a link to buy the cable required at decent prices bassboy

 

Thats not always the case, 35mm2 does not always mean 35mm2 conductor....I have seen some cheap cables that are claimed to be 35mm2 but will barely pass as 20mm2 (like the 70mm2 example I gave earlier which would only really pass as 50mm2 with the cables I regularly use.

Heres a quick comparison of some cables that were meant to be 20mm2 (4g)



I agree the thick power cables are for high current draws...but over the 3-4m run from back to front, I would definitely use a minimum of 4g (20 or 25mm2 cable) as long as its OFC. If its CCA cable then I would use 35mm2 cable as you stated.

James, welding cable can be had for pretty cheap on eBay

 

I've only ever used welding cable, and a simple guide as to whether it is the correct size or bulk...is simply how if fits into a lug. If it was loose it would be immediately apparent it was wrong.

I've never had that to be the case. Maybe the audio cables are more likely to see cheap substandard product given the huge market ?

Welding cable is more likely to be a smaller market.

 

Possibly but we have noticed a a variation in welding cable to...

As long as you use well regarded cable or have used it before and know its good stuff then its all good

 

i suppose using the ford connect starter which is more efficent than the standard cossie one would help in this situation as your 3metres+ from the battery.