soldering a battery lead

[elton]

The difference between a soldered joint and a crimped joint is that whereas a crimped connection is simply a mechanical, contact joint, a soldered joint is a molecular bond. The soldered connection being far more resilant to vibration and electrolytic corrosion failure. Maybe someone with more expertise than myself, a one-time electronics technician qualified to work on RN battleships, could correct me if this isn't so.

[ccscott49]

I will correct you, a soldered joint is more likely to fail on battery leads, than a crimped joint, but of course you dont need to believe me, maybe your training is a bit out of date? Crimps have replaced many soldered joints, due to stress/fatigue fractures and most certainly on battery connections.

[elton]

I will correct you, a soldered joint is more likely to fail on battery leads, than a crimped joint, but of course you dont need to believe me, maybe your training is a bit out of date? Crimps have replaced many soldered joints, due to stress/fatigue fractures and most certainly on battery connections.

Show us some evidence please. I'm not after an argument. If I'm wrong I'd rather not be giving duff info.

[nedmin]

whats all this about soldering,if its done properly it will last forever.I would trust a good soldered connection any time against a crimped one.If its that bad why do they solder armatures on motors.these whirl round at 1000,s of revs a minute and carry amps at the same time.I,ve seen too many bad crimped joints in my working life to get too keen on them,especially on aluminium cables.

[nedmin]

ps if there is any green(copper oxide) on the cables you are trying to solder,pour some boiling water on it, might also not be a bad idea if there isnt, because it will get rid of any grease for you.

[ccscott49]

No worries, I understand you are not looking for an argument.
The reason I was taught, was the soldered joint, especially on battery/starter cables, was the hard end of the wire, due to soldering, failed due to vibration/flexing work hardening the joint or similar which caused first cracks, then corrosion, (stress crack corrosion failure) then total failure, This was on mainly vehicle wiring, but also on aircraft wiring, as I was an aircraft tech first then artificer vehicles (long story). Of course as the other poster said, armatures etc are still soldered, I would love to see a method of crimping an armature! or circuit board, But the joints themselves are not subject to flexing and work hardening.
Cant quote any more detail than that, given time, I'm sure I could find something, but I'm at anchor in Puerto Soller, Majorca and cant really be that fussed! Cold beer, aft deck etc.

[philip_stevens]

I went on board yesterday for the first time on a couple of weeks. Job #1 is to reconnect the batteries, as I always disconnect them when leaving (), and then to run the voltmeter over them.

Generator batt (Single 12v 110 AHr) OK at 12.6

Domestic batts (serial 2x110 AHr) OK at 12.5v each

Engine Batts (serial 2x110 AHr) OK at 12.5 ish each, but when checked across the 24v terminal - OOPS ! zero, nada, 0 volts at all.

A little bit of investigation came up with this: the small + to - connection had come unsoldered.

Now I have a small soldering iron (which is clearly not going to be tough enough/have enough heat), and a butane gas jet/torch. What I don't know - as I have soldered anything on this scale before) is how to get the heat into the pinch clip and the cable, and what sequence (i.e. do I heat them separately, join them and then apply the solder core; or join them, heat them and then add solder.) My other concern is not burning the insulation.

All advice gratefully received ! Thanks.

I have just had to re-solder a 16mm earth wire into a tag on a ship. To prevent burning the insulation, I wrapped a wet rag around the outer insulation.

To prevent de-soldering the other end, allow it to rest in water. This way, it will not de-solder - even the wet rag should prevent de-soldering. Apply heat (maybe from a small blowtorch) to the outer end of the tag with the wire in place (as VicS says, make sure it is clean and then clean again). Apply some plumbing flux to the cable end and inside the tag before mating the cable to the tag - it is better than soldering flux. Apply heat, and as soon as the original solder starts to liquefy, add some more solder to fill the tag. Allow to cool naturally - don't plunge it into the water. After it has cooled to solid, but before it is completely cooled, wash any excess flux from the joint.

It is sometimes necessary to solder when crimping gear is not available, and connections must be made soonest.

[Bobobolinsky]

Hi a brand new one is only £4.50- £8.75 (depends on length, you can buy them from 50 to 300mm) from your local truck parts factors.

Robin

[Bilgediver]

The difference between a soldered joint and a crimped joint is that whereas a crimped connection is simply a mechanical, contact joint, a soldered joint is a molecular bond. The soldered connection being far more resilant to vibration and electrolytic corrosion failure. Maybe someone with more expertise than myself, a one-time electronics technician qualified to work on RN battleships, could correct me if this isn't so.

The reason for not soldering has nothing to do with the electrical properties.

When a thick multistrand wire is soldered in the way we are suggesting then the solder will form a sudden stress raising location at its surface.

This may not be a problem in this instance though to get it right the way Vic suggests is not for the inexperienced and faint hearted. The job is made difficult also as the lug has a vent hole in it through which the solder will escape unless plugged as the solder will be in the lug like a pool of mercury trying to escape.

Yes it can be done but might take the inexperienced a few goes before the plug of solder totally attains the correct temperature by which time the plastic will probaly have gone up in flames. Not even enough wire unless a big loop is formed to slip on heat shrink to use to cover the damage to the insulation....Yep Vic can no doubt do it and yes I have installed systems in this way but not where there may be vibration at the lug as in this case the wire will fail, IE lugs on the big terminal of starters.

[elton]

the solder will form a sudden stress raising location at its surface.

I don't know what that means

This may not be a problem in this instance though to get it right the way Vic suggests is not for the inexperienced and faint hearted. The job is made difficult also as the lug has a vent hole in it through which the solder will escape unless plugged as the solder will be in the lug like a pool of mercury trying to escape.

What does that matter? The intent is to wet the surfaces of the two components (the terminal and the wire) with solder and then to keep them in contact until the solder 'freezes'. There's no need to encase the components in a blob of solder.

Yes it can be done but might take the inexperienced a few goes before the plug of solder totally attains the correct temperature by which time the plastic will probaly have gone up in flames. Not even enough wire unless a big loop is formed to slip on heat shrink to use to cover the damage to the insulation....Yep Vic can no doubt do it and yes I have installed systems in this way but not where there may be vibration at the lug as in this case the wire will fail, IE lugs on the big terminal of starters.

A suitable heat sink will prevent damage to the insulation.

I'd agree that experience will produce a better joint, but an inexperieced solderer can detect a bad joint simply by looking for the symptoms as I described. This isn't necessarily so for a crimped union. Most failures of crimped connections that I've seen have been due to use of the incorrect tool and/or bad technique. A bad crimp is unlikely to appear so to a novice, whereas the symptoms of a badly soldered joint are pretty obvious.