Leisure battery cable routing to boot

[Rob]

Need to replace my shocking (no pun intended) spit charge system for various reasons. Firstly it was dangerous, with the positive terminal on my leisure battery very close to the body/bonnet and secondly the bracket on my cyrix relay has fatigued and was no longer attached to the vehicle so I had to remove the entire system due to safety concerns.

I have decided to relocate the battery to the boot as I would like to keep 2 full size starter batteries and I am not sure how to route the 2 50mm cables to the back? Will there be enough space to take them through the bulkhead using original grommets and along the edge of the carpet? If so I would prefer to route it this way than through the the boot floor somewhere. I would also like to keep the rear heater as I do use it occasionally, really gets a lot of heat into the cabin on those very cold days so can't route the cable through were the pipes used to go.

 

[Towpack]

I ran a single 16mm cable to the boot area to feed some extra power outlets and managed to feed it through internally under the door sill trims but it was a tight fit. I reckon you will struggle to fit 2 x 50mm cable in there. I'd run them along the RHS chassis rail using proper clips, not cable ties and into the rear body cavity behind the RHS trim panel. There's a large grommet in the floor where the sunroof drain tube feeds through. You may be able to squeeze the cables in alongside the drain tube.

 

[Rob]

Sunroof drain? I don't have such luxuries. Could you give me more of an idea where I can find this grommet? I already have 2 16mm cables running under the door sill trim but I will be pulling these up. can'r remember how much space there is in there though.

 

[Julian T]

Lie down under your cruiser, look behind the rear axle out board of the chassis rail, you will be looking at the bottom of the rear floor, there is a rubber grommet facing the chassis member, if you like I can try get a photo of the area tomorrow as it is raining and black out there atm

 

[Rob]

Julian thanks for the info, will have a look after work tomorrow if its not raining. A photo would be handy as well

 

[Chris]

That's where I ran my 50mm cable. The chassis make the perfect mounting point for cabling. I did try running it inside the chassis, but it was taking me forever so I gave up on that in the end. Sunroof drain point is handy. Worth looking inside your sills at that point too. Mine were inches deep in mud. Pull the grommets out and flush with a hose pipe.

Chris

 

[Rob]

If only I had somewhere to connect a hose pipe too... One day I will, I hope I will at least...

 

[Jon Wildsmith]

why such heavy cable Rob?

 

[Graham]

500mm is a good size, but really a tad on the OTT.

Have you got the 50mm already, or is this on your acquisition list?
I went for 35mm welding cables, 1 x pos & 1 x neg.

No harm in 50mm, but just more awkward.

Gra.

 

[Graham]

Sorry, meant to say 50mm cable, NOT 500mm
Is the edit working yet? or have I not found it ?

Gra.

 

[Steve Wright]

why such heavy cable Rob?

Hi Jon
Thats easy ! its called Volt drop, the thicker the cable the less the volt drop.

example:
35mm cable 14 volts 10mt run drawing 100 amps 1.013 volt drop so at the end of the circuit it would be 12.98 volt
50mm cable 14 volts 10mt run drawing 100 amps .708 volt drop so at the end of the circuit it would be 13.29 volt

So baisicly the difference between charging or not charging a battery !

 

[Rob]

What Steve said. Also I do not want to worry melting the cable when using the leisure battery to help start the engine. I have managed to melt insulation on standard jump leads before so don't wasn't to have that happening again on this cable. Will be fused at 300A (time delayed) at both ends for safety reasons as well.

Sent from my GT-I9100 using Tapatalk 2

 

[Jon Wildsmith]

any volt drop is bad news for charging, even using 50mm cable, so if charging the battery is the concern then a charger is a much better solution. The usual reason for 50mm cable is to help out when winching, but Rob has a hydraulic winch, that's why I'm asking him if he really needs 50mm cable

 

[Rob]

I don't have a winch but I do have a hefty starter motor which is capable of pulling huge stall current for longer periods when the voltage is too low.

Sent from my GT-I9100 using Tapatalk 2

 

[Chris]

IIRC the reason I went with 50mm to the back is that I put the voltage sensing relay in the back. If I suffered losses in the cable supply to the charger, it might not be in the range needed to detect supply and therefore wouldn't switch. If it was under the bonnet, it would get an accurate 'feed' and yes there would be losses in the supply to the battery - but it would still get a charge of the right order.

Would still like bigger alternator though, although with the rear winch running from the rear battery, I have never run out of power yet.

Chris

 

[Jon Wildsmith]

I don't have a winch but I do have a hefty starter motor which is capable of pulling huge stall current for longer periods when the voltage is too low.

But you have 2 big batteries in the engine bay to take care of starting, on a manual truck as well, which gives you more options in an emergency? I'm not saying you don't need 50mm cable, I'm just asking why you think you do

 

[Rob]

I am thinking of the situations when the front 2 batteries are flat/almost flat. It has happened to me a few times and when I just used a single car to jump start it is not enough, so will engage the split charge relay and put jump leads on the passenger battery and it should start. This is the only reason I have gone for such thick cabling as I cannot be bothered to dig out the leisure battery from the boot to jump start it. Under these conditions the current draw from the leisure battery can be significant hence the thick cabling.

 

[Jon Wildsmith]

if you left it on charge for a bit from the single car it should still work, just have to be more patient because there's 2 batteries to put some charge into. Won't work if one of them is properly dead though. Converting to 12v start would solve that problem, instead of needing an aux battery and another car to jump it...

 

[Rob]

Sounds like you have a 12v starter lying around desperate for a new home Jon... I guess you are right, not really solving the problem just working around it. Anyway I got the cable already so may as well use it. If I struggle to get it routed into the boot I will just use smaller cable.

 

[Jon Wildsmith]

I do have a 12v starter but it's not looking for a new home, it'll go in mine when I'm not busy with diffs