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Discussion Starter · #1 · (Edited)
Hi

I am running an 2 x 8mm cable from my second battery. The negative will be a straight through cable to the rear where its connected to a distribution block.

I am looking at cutting the positive in two locations, first under the bonnet to connect a 30amp manual override circuit breaker (http://www.narva.com.au/products/browse/metal-manual – part 54730. ) I will then run from the circuit breaker through the firewall to under the dash where I will have the first distribution block (http://bluesea.com/category/5/21/products/5028 ) . I will then run from this distribution block to the rear distribution block (http://bluesea.com/category/5/21/products/5025 ).

In the rear I will connect a 80l waeco to one of the terminals on the rear distribution block. I want to ensure there is minimal current loss hence using a thick 8mm cable and connecting directly to the negative on the battery. My concern is if I cut the cable in two locations will this cause any voltage drop that might impact the fridges performance?

Also, from what I have read some people recommend running the negative from the battery for a fridge some say its not required. To be on the safe side I have decided to run the negative direct from the battery instead of earthing onto the car at the rear.

Thanks
 

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My power at the rear is earthed at the chassis there. Has been for 10 years. I run 2 50 lt fridges, lights, invertor, etc. Never had a problam. Make sure you have a good earth from your duel battery to engine and chassis and body. As for cutting the cable, you should be fine providing you use quality eye crimps and solder them.
 

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Chev 6.5 litre V8: no substitute for cubic inches
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On the basis of being "on the safe side", I would agree that it might be wise (although not 100% necessary) to run the separate earth cable to the back.

On the other issue of the positive cabling, have you thought about running 2 of the 8mm cables through the firewall, each with it's own circuit breaker under the bonnet? That would minimise the chances of voltage drop between the 2 distribution blocks (as they would be totally independant of each other).

I must add though, that I am a great believer in having the 2nd battery actually in the back of the vehicle close to the items that it is going to have to provide power to. If you did it that way, you would just need to run the single 8mm cable (via the circuit breaker), through the firewall and on to the 2nd battery (with another circuit breaker close to the 2nd battery). The items you plan to power-up off the under-dash distribution block are probably not all that power hungry, so you could perhaps get away with a 6mm cable from the rear-mounted 2nd battery to that block.
 

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Hiya Puck.

There is always a loss at any interconnect but when done correctly it is so low as to be considered negligible and usually the loss due to cable resistance is higher.

Like Frostys says.. If you are after minimum loss I would strongly suggest using good quality connectors and solder them don't just crimp them.

The 80 litre Waeco's are notorious for "under voltage sense" issues which is about their only fault. I had one for several years and was absolutely fantastic frig which I sold only because it didn't fit in my current rig layout.

So, I agree that a Neg return cable is a good idea in your case as even 1/2 a volt loss thru a Chassis return will possibly affect the frig yet everything else runs OK .

I also agree with Roachie. If possible having the battery close to the items drawing from it is a good idea. I had the Aux battery in the rear of a GQ and it sat beautifully in the foot well of the 3rd row seat with a tiedown. Worked really well.

Bottom line... quality connectors soldered not crimped and you should see only about .3 of a Volt drop at the back distribution block.
 

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Discussion Starter · #6 ·
Thanks for all the info, it’s a great help.

When you mention solder the connection do you mean crimp and solder?

For example as the cable is too thick for the standard crimp connectors I am having to use sold silver connectors such as : https://www.whitworths.com.au/main_itemdetail.asp?item=4309&search123=10mm&intAbsolutePage=1 What is the best way to attach this type of connector? I don’t have a crimp tool thick enough, do I use pliers then solder at the end the cable pokes out of?

 

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Thanks for all the info, it’s a great help.

When you mention solder the connection do you mean crimp and solder?

For example as the cable is too thick for the standard crimp connectors I am having to use sold silver connectors such as : https://www.whitworths.com.au/main_itemdetail.asp?item=4309&search123=10mm&intAbsolutePage=1 What is the best way to attach this type of connector? I don’t have a crimp tool thick enough, do I use pliers then solder at the end the cable pokes out of?


Just solder them. No need to crimp.
 

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Discussion Starter · #8 ·

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Ok... first the Connector

With that connector don't even attempt to crimp them. If you don't want to have a crack at soldering them yourself just take the cable to an Auto Sparkie and ask him to do it.

The simplest way is with a small butane torch.

Trim the insulation from the cable and test fit it into the connector to get the correct length of stripped wire so the wire almost bottoms out when the insulation gets to the connector. Don't trim off too much as he insulation will creep back a bit in the next step.

Heat the end of the cable and thoroughly "tin" the exposed copper with solder to within a mm or two of the insulation. Keep the Butane Torch away from the insulation as the solder will wick up the wire when it's hot enough anyway

Pop the connector into a vice or whatever so it is vertical and heat until you can melt solder into it and fill about a 1/4 to 1/3 of it with a pool of solder. If the wire was a tightish in the test fit then you need less solder than if it was loose as the solder needs to take up any gaps.

When the there is a pool of molten solder in the connector introduce the tinned wire and allow a second or two for all the solder on the wire to remelt and bond and remove the heat but support the cable for 10 or 15 seconds till the solder cools.

Results in a super strong connection that will not corrode and handles maximum current with minimum voltage loss :driving:

Now the underdash...
Personally I wouldn't put a break in the 8mm cable under the dash. I'd run a seperate smaller feed from the battery terminal or rear as all the stuff you mention will happily work on lower voltages and also draws minimal current.

Lastly... not sure why you want to run your GPS, UHF etc off the Aux Battery
So a few rules of thumb that normally apply
1. If the accessory is mainly used when driving normally it is connected to the Cranker
2. If the accessory is mainly used when camped/vehicle is off/etc normally it is connected to the Aux
Now obviously different people may have different reasons behind power circuits IE maybe they are a CB hound and use the UHF heaps when stopped but if you use the above idea then it will simplify your installation a lot.

If that doesn't suit you... totally cool, just throwing it out there :cool:

I luv modd'ing my truck and have rear Fridge outlets Engel and Hella style, Anderson Plugs for the Camper, Worklights, Camera's and Brake/Turning Repeaters on the Roof Rack... it's gangs of fun customising the 'Troll eh...
 

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Discussion Starter · #10 ·
Ahh OK.. I see Thanks for the info.

After you mentioned this I went you-tube-ing I located this video that I think is similar to what you described?
YouTube - How to make up Anderson plug jump leads for a land rover Defender or any vehicle starts around 5mins.

Good point, I will leave the 8mm cable direct run a smaller cable for the UHF and run the GPS/other small radio off the car. To do this should I just connect into the back of one of the 12v cigarette cables?

Also, I was hesitant on running more cables through the firewall as I am running out of room in the factory grommet. Its hard enough to get too with the ABS system in the way. I cant get to the one in the centre of the car or on the drivers side. My only other option is to poke a hole in the factory grommet or drill another somewhere.. Do you have any tips here?
 

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1) Buy the correct terminal for the cable in question - don't "fill the gaps" with solder LOL !!!
2) Crimping is always preferably to solder, always, accept it OK. If you don't have suitable crimps, just take it to a sparky, for a fiver in his back pocket, he should crimp them up for you - job done.
 

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Hiya Tom...

Point 1. That terminal Puck has specified is the correct terminal for that cable and is specified as a "Solder Only" terminal and is NOT suitable for crimping as per the first section of my post.

Point 1 again. You have to "fill the gaps" with solder, that is the whole idea. Specifically the gaps between each individual strand of the cable itself, the wall of the connector and the base. I usually "LOL" when people don't do that and their connection is crap.

Point 2. There is no way in the world crimping is "ALWAYS" preferable to solder but I totally agree there is applications for both.

Solder - Solder forms an electrical connection with minimum loss, maximum current carrying and no damage to the cable strands and prohibits internal corrosion in the joint.

Crimps - Crimps form a mechanical connection and cannot meet the same electrical performance as a soldered connection, damage the cable strands and still allow potential internal corrosion of the joint...

How many people on this forum have experienced electrical faults from a crimp failure due to corrosion of the wire inside the crimp and what looks OK on the outside is a blue powdery mush on the inside?

Do I use both forms of termination, Hell Yes, and probably 95% more crimps than solder at that. Crimps are 10 times faster to do, easy to prep and usually reliable when used with the correct crimping tool plus a bit of heatshrink or amalgamating tape depending on environment BUT solder connections still have a use even in this day and age and evry manufacturer admits provide the best electrical connection characteristics.

Bottom line is there will always be a debate on Solder versus Crimp but there are uses for both.
 

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I wasn't going to enter into the debate between crimping and soldering; but I will!!! ;)

I used to always solder the larger joints and found they worked well......for a while! Then they would fatigue and lose their grip/conductivity. Also, solder itself is NOT a great conductor of electricity.

If you can afford it, why not buy something like this: ELECTRICIANS CABLES CRIMPER ELECTRIC LUGS TOOLS POUCH - eBay, Test Equipment, Electrical, Industrial. (end time 31-Oct-10 23:12:49 AEDST)

I've done a lot of soldering over the years. The problem with soldering is that the area immediately behind the joint becomes brittle and fatigued. The copper strands cannot flex as well as a crimped joint.

However, like the Evil Twin also said, there are uses for both forms of joint, I just happen to have found that where there is ANY CHANCE of vibration, it is preferrable to crimp.
 

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I am with Roachie, With battery cables I always use to crimp the lugs and then seal up the ends with solder, making sure the solder did not run back up the cable.

But now days I find crimping and using heat shrink works a treat and it so much quicker then soldering.

Just make sure you are using the correct size lugs for your cable.
 

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The Bear
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I usually crimp then solder, but one thing I always do is slide on a length or two of heat shrink well along the cable and hhen the hot work is finished slide the heat shrink over the lug one bit at a time finish it then slide the nex bit on and shrink that. You can get a "heavy duty" type heatshring from ectrical distributors that is better than the thin stuff you get from supercheep and bunnings. I just think that this supports the cable a bit more after the soler joint and relieves the fatigue issue Roachie mentioned
 

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The facts

Crimping ( without solder ) is the only method recomended in aviation, solder causes fatigue, not just in the solder but also ( and this is the reason it's not allowed in planes ) in the wire going into the soldered block. And I think the stresses our vehicle are put to are somewhat similar to a plane or helicopter.

SORRY GUYS, BUT IT'S A FACT.
( google it if you don't beleive me)
I am sure several people will have used solder and it has done well for many years but if you where 10,000 feet up I am sure you would like to know that you have used the best method available to you.
I bought a Hydraulic crimper and propper copper cable cutter and I could not be happier with it.
Cheers Gordo
 

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As I said, accept it OK ! But, if you still want to solder, then I'm not going to stop you eviltwin (sounds like you've bought the wrong hardware, buts that's not of my concern).

I do agree that there are times when it's just easier to solder, but all points in the above supporting posts are good ones. Crimping then solder is just mental insecurity and pointless - or you've got the wrong terminal for the cable !
 

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BORDERTREK 4X4 & FABRICATION
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As for crimping, I worked on a 400Kw heat pump on Friday that had a control panel 3 ft wide, 6ft high and was completely full of circuit breakers, contactors, timers and controllers and there was probably 1000 connections in that panel and not one was soldered. At least 100 would have been terminated with crimps however.

The unit had 600Amp 3 phase cables coming into it and they were all crimped terminals. For the compressors I installed, I had to use proper crimpers on the connecting terminals that leave an impression in the sleeve of the terminal that state the crimp depth so it can easily seen to meet the certified specifications.

I have seen crimpers that look like bolt cutters for cables that are over 1/2 thick and if a crimp will handle these sorts of currents and demands, you can bet your backside they are up to anything you'd find in a vehicle.... IF the crimp is done properly and not with some $2 crimper and crap terminals from the local Asian junk shop.

Solder terminations are never used in domestic, industrial or any other similar sort of wiring and I believe in many applications it would be highly illegal to solder anything.
No you wont find many soldered connections these days. Only in very low current low voltage applications. Problems are the dry joint syndrome or heat soak from over current or nearby mechanical heat can melt the solder in the joint. Wire falls out, touches a negative side or ground....................shorts.

Yes I have a set of those 'boltcutter' size crimpers, they go up to 120sq.mm conductor. They can squash the strands into a 'solid' hex of copper. After each crimp I try to pull of the lug with pliers. If it doesn't budge, it passes. If it moves, it gets cut off and done again. Electrician mate (and most sparkies) do this all the time on crimp connections of all sizes. Good habit I reckon.

As for volt drop through connections, I've measured the volts each side of some of my crimped or 'bolted' connections and never had any loss. If the cable is sufficient size there shouldn't be any, or very little volt drop over the whole length of the run either. You wouldn't want more than 3% drop in a 12V system, up to that will keep any 12V appliance working efficiently.
 

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The Bear
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Why aren't the components in the circuit board in my computer and TV, and the navigation and control system in the aeroplanes I fly on just crimped together, surely that would be more than enough to get it all to hold together and work efficiently. :rolleyes:

But each to his own, but seriously surely the reason the reason that terminals aren't soldered in most applications is cost and time.

I acknowledge that in serious high frequency vibration applications fatigue of joints would be an issue, however you could hardly compare an aircrafts wiring requirements to those tooling around town or down the highway, or the occasional trip off the tarmac, in a patrol, Toyota LC, or any other motor vehicle, except perhaps a F1, or a terrafugia transition (look it up).

A properly constructed solder joint is Ok for most applications, and providing care is taken with support of cabling fatigue is not an issue.

I think this argument about soldering a few terminals in your vehicle is getting out of hand when we start comparing the results to a 747 or such.

I am sure that some of us have bought some products that were "crimped" and the wiring has just pulled out of the joint because it was "done on the cheap" - and thats is the implication that is made with some people doing work at home, it is "on the cheap", instead of the little more investment in time and care to produce a possible better outcome, 'cause thats how we like it.

Each to his own.
 

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BORDERTREK 4X4 & FABRICATION
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Why aren't the components in the circuit board in my computer and TV, and the navigation and control system in the aeroplanes I fly on just crimped together, surely that would be more than enough to get it all to hold together and work efficiently. :rolleyes:
Circuit boards are a whole different animal. The joints are fixed to a board and they're mostly very low current. You can't crimp board circuits anyway and it'd be economically unviable. We're talking about soldering cabling though aren't we?
 
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