Do i need a crimping tool?

[Marsupial]

Ahh the to solder or crimp argument, with small wire that carries low current I ve seen the same number of failures on soldered and crimped joints, so its all about "the application" does it vibrate, does it move, does it get wet sort of ideas. But on large wire that carries high amperages like starter motors, windlasses and bow thrusters; if you solder ONLY you run the risk of the wire heating when current is applied and the solder heats till it runs and the joint falls apart. Brazing large joints is a better option but most are crimped and sealed.

 

[pvb]

...if you solder ONLY you run the risk of the wire heating when current is applied....

This would only happen if the cable is seriously under-specified and/or incorrectly fused. With properly-specified cable and fuses/breakers, there'll never be enough heat to melt solder.

 

[elton]

This is a re-run of previous threads on crimping and soldering, and a re-run of the same semi-informed opinions on soldering, crimping, and soldering vs. crimping. Only one thing is clear: when buying a second-hand boat, check the wiring, and check every connection for evidence of amateur bodging.

 

[maxi77]

This would only happen if the cable is seriously under-specified and/or incorrectly fused. With properly-specified cable and fuses/breakers, there'll never be enough heat to melt solder.

My main concern with soldering the heavier cables is that the ammount of heat that needs to be input to the copper to ensure that the solder flows properly will damage the insulation quite away from the joint, and most heat shrink is not as heavy duty as the stuff on heavy cable.

Crimping is also safer, no fire, and a lot faster.

 

[pvb]

My main concern with soldering the heavier cables is that the ammount of heat that needs to be input to the copper to ensure that the solder flows properly will damage the insulation quite away from the joint, and most heat shrink is not as heavy duty as the stuff on heavy cable.

In my experience of soldering lugs on 35 sq mm cable, only about 3-4mm of insulation appeared heat-damaged.

 

[Malish]

This is a re-run of previous threads on crimping and soldering, and a re-run of the same semi-informed opinions on soldering, crimping, and soldering vs. crimping. Only one thing is clear: when buying a second-hand boat, check the wiring, and check every connection for evidence of amateur bodging.

wise words, succinctly put...

 

[Marsupial]

This would only happen if the cable is seriously under-specified and/or incorrectly fused. With properly-specified cable and fuses/breakers, there'll never be enough heat to melt solder.

never say never! what happens to amps if volts drops? what happens to heat if the resistance goes up? have you ever seen an installation without breakers and/or fuses - I thought so.

Solder without a crimp is asking for trouble, it only needs the live on the apparatus to fall off and touch something thats earthed and your in for a new boat!

 

[pvb]

never say never! what happens to amps if volts drops? what happens to heat if the resistance goes up? have you ever seen an installation without breakers and/or fuses - I thought so.

Solder without a crimp is asking for trouble, it only needs the live on the apparatus to fall off and touch something thats earthed and your in for a new boat!

No, I've never seen a windlass installed without either a breaker or a fuse.

If you've been following the thread, you'll know that I said "I used a combination of "crimping" the lugs on to the cable with Mole grips, then soldering them using a small butane blowtorch".

EDIT - By the way, what do you think "happens to amps if volts drops"??

 

[saltwater_gypsy]

I have used a "hammer crimping" tool with good results. Her is an example at £23 :http://www.thetoolboxshop.com/0-703-90-heavy-duty-crimping-tool-8109-p.asp
The one I used was even simpler and I think I got it from Merlin.

 

[lw395]

If you are going to solder big wires, may I suggest instead of using a small blowtorch, use a fairly big one?
Get the heat where it is needed quickly, before it spreads where it is not wanted.
Any joint not made in under 5 seconds is likely to be poor.
Use a wet cloth around the insulation to keep it cool.
That way the solder will not wick very far up the cable.
Use some decent flux, such as a 'no clean flux pen' from RS.
Crimp the joint as best you can using pliers or whatever, this holds it in place while you solder, and indeed if meltdown occurs. And reduces the amount of solder needed.
Use low melt or 60/40 tin lead solder, avoid the dolphin-friendly stuff if at all possible.

Whether the joint is crimped or soldered, if it is subject to fatigue it will fail much sooner, so tie all the wires together and support them locally, so that the flexing is not at the joints. The length that is flexed (e.g. by engine movement) should have a good curve in it.


I would normally get these crimped professionally, but sometimes that's not easy. A good well supported solder joint is fine.

 

[PCUK]

Make up a simple crimper that fits in the vice! Good as the real thing only heavier!

 

[lw395]

Make up a simple crimper that fits in the vice! Good as the real thing only heavier!

You mean like the Ormiston tool I use for crimping copper ferrules onto dinghy shrouds?
It does up with two M8 bolts and is pretty effective.

 

[Marsupial]

No, I've never seen a windlass installed without either a breaker or a fuse.

perhaps not but I HAVE seen 15ft of the right sized battery cable on fire caused by faulty connections!

If you've been following the thread, you'll know that I said "I used a combination of "crimping" the lugs on to the cable with Mole grips, then soldering them using a small butane blowtorch".

thats good I am not arguing with that approach

EDIT - By the way, what do you think "happens to amps if volts drops"??

AMPS increases and things get hot.

 

[pvb]

AMPS increases and things get hot.

I'm not sure how you've come to the conclusion that current increases if the voltage drops.

As an example, suppose I have a 25 watt navigation light on a boat. Suppose a 12v battery is connected to the light. Initially, the light will be bright, but as the voltage drops the current flowing through the bulb also drops, and the bulb dims.

If, as you claim, the current increases as the voltage drops, surely the power available to the bulb would be more or less constant, so it wouldn't dim.

 

[vyv_cox]

EDIT - By the way, what do you think "happens to amps if volts drops"??

AMPS increases and things get hot.

That's the problem with getting older - everything changes. I'm sure I remember when I was at school that V = IR. So by that old-fashioned reckoning, V/2 = I/2R.

I suppose nowadays that V = R/I, thus explaining why the amps increase when the voltage reduces. Fortunately my boat is getting nearly as old as me and it still works by the old rules.

 

[pvb]

Fortunately my boat is getting nearly as old as me and it still works by the old rules.

 

[lw395]

That's the problem with getting older - everything changes. I'm sure I remember when I was at school that V = IR. So by that old-fashioned reckoning, V/2 = I/2R.

I suppose nowadays that V = R/I, thus explaining why the amps increase when the voltage reduces. Fortunately my boat is getting nearly as old as me and it still works by the old rules.

Actually, we don't often use our 12V systems to drive resistors!
In fact the current drawn by a motor (such as a starter or windlass) CAN go up as the volts drop, because it will be much closer to being stalled and doesn't generate the back emf. It's no longer running at such an efficient point.
Also as it runs slower, it has to run for longer....so more heat. Particularly in the windings of the motor itself.
Also things like inverters can operate as constant power devices, the regulation in them can cause the input current drawn to rise as the volts drop.
Ohm's Law only applies in ohmic systems, the original has the phrase 'metals at a constant temperature' in there somewhere.

However, lunchtime digressions over, Marsupial makes a very valid point about looking after the connections as well as sizing the cable.

 

[Trundlebug]

Lots of interesting solutions to the OP but no-one has suggested my method, perhaps I should have patented it!

All you need is a small anvil or piece of metal plate, a lump hammer and a blunt cold chisel.

Easy, fast, satisfying and very effective. Certainly for larger crimps, a lot easier than any crimping tool and dirt cheap.

Two crimps per connector, combined with tight sealing with insulating tape afterwards as mentioned above, and job done.

I've used this method on two boats now, mine and a friend's, rewiring all the main battery cables. Gives a tighter crimp than any tool, with less effort!

 

[vyv_cox]

Actually, we don't often use our 12V systems to drive resistors!
In fact the current drawn by a motor (such as a starter or windlass) CAN go up as the volts drop, because it will be much closer to being stalled and doesn't generate the back emf. It's no longer running at such an efficient point.
Also as it runs slower, it has to run for longer....so more heat. Particularly in the windings of the motor itself.
Also things like inverters can operate as constant power devices, the regulation in them can cause the input current drawn to rise as the volts drop.
Ohm's Law only applies in ohmic systems, the original has the phrase 'metals at a constant temperature' in there somewhere.

However, lunchtime digressions over, Marsupial makes a very valid point about looking after the connections as well as sizing the cable.

I thought we were discussing crimped joints? It doesn't surprise me that there are exceptions to V = IR, but I don't think that crimped joints is one of them.

 

[lw395]

I thought we were discussing crimped joints? It doesn't surprise me that there are exceptions to V = IR, but I don't think that crimped joints is one of them.

A bad crimp with a bit of corrosion can be very non-ohmic. It can look fine with a multimeter or at small current and fail at full load.