Common Mistakes Made, Sloutions To Problems In Terminals/Connections (Technical)

[JeepHammer]

1. Undersize Wiring.
While I use the turn of the 20th century Brown & Sharp scale, when they built a crap load of DC stuff (subways & electric trains, entire local DC power grids, etc) and I've found that sizing scale to be a LOT more efficient, when I started with long DC Buss lines, then Lithium batteries I found a lot of losses, corrosion damage, etc.

The Brown & Sharp scale was designed for HIGH POWER DC and 100% duty cycle, not part time use and low voltage/amperage (automotive) use. It saved a LOT of aggravation and losses in my systems.

Now I mostly add in 20-50% of the top expected amperage.

With 50% oversize conductors, at 100% load AND duty cycle the cables are actually running at 2/3 capacity reducing resistance. Any corrosion resistance issues are covered by the extra capacity.

The added capacity also takes up the slack when corrosion creeps in. Corrosion is 100% guaranteed in every system, simply because you can't keep oxygen/moisture out entirely. Any and all gaskets/seals are 100% going to fail at some point in time, so plan for it.

2. Making Proper Connections!
I see a LOT of confusion/improper information about connections.

First off, those little barrel crimp terminals expand/contract with heat, loosening up on the wire.
The terminal material often IS NOT pure copper (or copper at all), or the plating doesn't get along with the terminal material. (Zinc plating for instance).

Crimping is a MECHANICAL connection. Period. It simply presses two materials into each other.

While this will work for an electrical connection FOR A WHILE, it doesn't do a thing to keep moisture/corrosion contamination out of the stripped copper cable (stripped to make the terminal connection).

This is where a proper SILVER BEARING ELECTRICAL SOLDER comes into play.

After crimping, simply use solder to fill any gaps, 'Tin' the exposed wire. Filling AIR gaps with highly conductive silver solder keeps contamination out, makes MORE electrical contact area, and coating raw copper wire keeps moisture from creeping up the wire strands where it can (and will) cause corrosion inside the insulation.

There doesn't seem to be any argument about Heat Shrink Insulation Tubing. I prefer the glue lined so it seals out moisture in the first place. The industral version takes real work to get off, so it REALLY seals the insulation to the terminal.

With smaller crimp terminals, the solder once again closes up any air gaps, bonds the wire directly to the terminal, and something no one has mentioned I've seen, it seals up the open barrel/wire ends. Just condensation on terminals will run water directly into the copper ends... Solder stops that, it also stops the wire from loosening up as the terminal heat cycles.

Mechanical Crimp, Solder Connection/Seal, Heat Shrink Tubing, equals one TOUGH, Semi-Perminant connection.

3. Terminal & Lug MASS/Contact Area.
You have a big, fat copper conductor, you get a lug with big hole, so lots of surface area at the terminal connection pad...

Then the terminal/lug has a little skinny, thin neck between crimp barrel and that contact area at the ring... That's a restriction to current at best, and an uncontrolled, unintentional FUSE/ignition source at worst.

Its about the MASS of conductor in the current path...

Flattened End Tubing is really popular. They are cheaper because there is less copper conductor (Mass). If the side walls and contact area that actually make contact with the opposite terminal ARE NOT EQUAL (or greater) than the cable mass, then it's a restriction.

The one terminal lug that never fails me, heats up at 100% capacity/duty cycle are cast copper, blind socket (no place for moisture to enter) industral lugs. Commony used in high power industral equipment, industral battery terminals, etc.

You WILL need an industral strength crimp tool, and you will pay about $5 each for them, bit they are as close to 100% bullet proof as anything can be.

4. Terminal Protection.
Unless you want your system to be disposable, then use one of two things each and every connection...

Sealing conductive grease to seal moisture out and enhance the ELECTRICAL connection,
AND/OR...
Use dielectric grease on top the connection to seal out oxygen/moisture.

If you have a system long enough, and soe of my Busses are over 30 years old, you abaloutely want to use some kind of sealer at every connection point.

Contact enhancer grease does exactly what the name implies, enhances contact while the grease blocks oxygen/moisture.

The dielectric grease seals oxygen/moisture from the ASSEMBLY, keeps moisture from attacking the conductors, the fasteners (bolts, nuts, screws, clamps, etc).

Nothing like having dissimilar metals fuse together in a corroded mess... Twisted off screws, bolts, studs, etc. This often as not results in replacment rather than repair of components since its difficult to impossible to repair twisted off studs, stripped threads, corroded contacts in a lot of components. Wire & cable terminal end replacment is one thing, but do you really want to disassemble an inverter that has epoxy sealer (potting) protecting the circuit board where the terminal twisted/corroded off?

5. Torque Limiting Device, Wrench Or Screwdriver.

EVERY SINGLE THREADED FASTENER has a torque (rotational force) specification for best performance.

If you haven't twisted off or stripped out bolts, screws, studs, etc then you haven't ever actually done any of this stuff... So the experienced know exactly what I'm talking about...

When I do inspections on my own equipment, or service calls/trouble shooting for others,
Visual inspection, then a 'Tug Test' (not yank!) on wires...

A full 50% of the time, something is loose...

Small crimp terminals have heat cycled and let the wire go, the small screws have been over torqued and lost compression or heat cycling has loosened them, etc.

Torque limiting screw drivers with good fitting bits start about $50, so do torque wrenches. They are a 100% cure for loose fasteners.

Checking every single connection fastener in a typical inverter install takes about 1 minute during maintance. I slap a sticker with torque specs inside the cover panel so the proper reference is right there at the work site... couldn't be easier...

Small screws are routinely 6 INCH pounds to 10 INCH pounds, just finger tight witj a screwdriver, while large terminal bolts/studs will rarely require more than 25 FOOT pounds, so a 200 foot pound automotive torque wrench isn't the best tool for the application.

 

[JeepHammer]

6. Conductor Materials Are NOT 1 Size Fits All...

The best elemental electrical conductors are as follows (and YES, this is 100% scientifically proven fact).

Silver, Copper, Gold, Aluminum, Zinc.

Silver is high conduction for AC & DC, it's low corrosion, and it melts at a relatively low temperature. The properties of silver bearing solder are such the silver moves to the outside of the liquid, so it makes contact with both wire conductor and terminal BEFORE it solidifies. This is the reason I stress SILVER BEARING SOLDER.

In very high amerage/temp situations i keep 'Junk' silver around to make these connections bullet proof. Coating breaker contacts keeps them from welding shut, silver is self healing when electrical arcs tunnel into contact material, it's insanely hard to beat the electrical properties of silver.

Copper is has high conduction properties, is much cheaper than silver or gold, handles DC current well, the reason copper is the choice for most electrical conductors. The draw back is copper is highly reactive to oxygen in the atmosphere so you DO need to protect any exposed copper.

Copper contact WILL weld shut, being crystalline in nature it doesn't heal very well when electrical arcs tunnel into it, etc. Good solid conductor, not so great in high heat (plasma) situation. Silver bonds reduclously well to copper, so silver bearing or silver solder.

Gold, the price, but it's very low reactive with most atmospheric contaminants and has excellent heat properties.

Aluminum is lighter weight, doesn't handle amperage/heating well, but does handle high frequency AC skin effect pretty well. Its thermal expansion rate is twice what steel is

Zinc has excellent electrical properties, but is toxic to handle/work, its also very reactive to atmosphere and surface corrodes quite easily so high frequency AC skin effect applications are almost useless. You might want to keep that in mind if you buy terminals that are zinc plated, while zinc is highly conductive, oxidized/corroded zinc is not.

Iron/Steel is a high resistance material, not even in the top ten best conductors. While steel makes a good fastener, there are better choices for high capacity electrical connections/terminals.

Copper is obvious, but copper bolts stretch, brass bolts are usually 'High Brass' or 'Cartridge' meaning it's a high Zinc alloy, about 70% Copper - 30% Zinc. Another choice is bronze, around 90% copper - 10% Tin.

These all are a lot more conductive than steel. These, with a copper washer, add contact area to your connection by conducting from far side of the cable terminal to the far side of the battery terminal for instance.

Recap... I pay a LOT to make and store, transfer the power around, I don't waste a Watt I can prevent through resistance.

Crimp THEN solder to seal up and make air spaces conductive, protect raw copper conductors. It's BOTH, not either/or.

Atmosphere WILL corrode your conductors. Period.
Doing what is reasonable to promote conduction, prevent corrosion helps you in both the short term, and long term.
Conductive grease, protective dielectric grease, heat shrink, solder 'Tinning' exposed copper will all pay off.

Use highly conductive fasteners. This isn't a high strength, structural situation, this is a high conductive situation.

Contact area is critical to amperage conduction, pay attention to the contact surface area AND the mass of the terminals. Copper washers and silver bearing solder is a good way to make any small terminal surface area larger without excessive resistance. The silver is more conductive than the copper, so use both liberally.

APPLICATION! APPLICATION! APPLICATION!

 

[Batvette]

Agree with all of the above except:

1. Silver Solder: from a marine electrical forum:

"The advantage to using 60/40 is you dont need as much heat, structural strength is not required, it bonds well with most of the common metals used (copper/brass) and gives you a visual guide as to the quality of the joint you just made (shinny and even surface). Eutectic solders do require more heat, offer little improvement in lower IR and provide little to no visual guidance as to how well your solder joint was made (dull finish)"
I will add I dont see the benefit in the increased conductivity if the wire is copper.

2. While I use torque wrenches when theyre called for, I dont agree with the point that if you havent stripped or broken a number of fasteners, you havent been doing this. I dont think I have any special skills on this but after wrenching nearly everything imaginable for most of my 61 years, I have a pretty good feel for what is good enough and can count ruined fasteners on one hand and thats because they were garbage product.
One of the things I wrenched on was F-4 phantoms in the navy. I worked on radar/avionics. The radome had to be opened to do nearly anything so it was typical to open and close several every day. They had specific torque values, 165 inch pounds, theres 4 and theyre very complicated. Our standard tool boxes didnt have torque wrenches and it was a pain to have to check one out from the tool corral when you needed one, so our shop chief had a system for QA on that. Once a year or so we all lined up at one of the aircraft, and tightened all 4 fasteners by feel. Any of us that got all 4 within 10 inch pounds of spec would be crew leader and responsible for securing the radome. I had no problem passing that test, and about a third of our shop did it too.
Id still go with a torque wrench on most things, and always use it on automotive work.
I think the most critical time for a torque wrench is assembling high end bicycles. I built an all titanium mountain bike about 15 years ago and used shimanos most expensive components. It doesnt take a lot to ruin that stuff, for instance the chain rings attach to the cranks with aluminum fasteners, I think they were something like 12 inch pounds.
On my 280ah eve cells I used new bolts, cut them into studs and JB welded them to the terminals. The idea of screwing a bolt into that aluminum terminal and repeatedly tightening it didnt seem like a good idea at all.

 

[Supervstech]

Agree with all of the above except:

1. Silver Solder: from a marine electrical forum:

"The advantage to using 60/40 is you dont need as much heat, structural strength is not required, it bonds well with most of the common metals used (copper/brass) and gives you a visual guide as to the quality of the joint you just made (shinny and even surface). Eutectic solders do require more heat, offer little improvement in lower IR and provide little to no visual guidance as to how well your solder joint was made (dull finish)"
I will add I dont see the benefit in the increased conductivity if the wire is copper.

2. While I use torque wrenches when theyre called for, I dont agree with the point that if you havent stripped or broken a number of fasteners, you havent been doing this. I dont think I have any special skills on this but after wrenching nearly everything imaginable for most of my 61 years, I have a pretty good feel for what is good enough and can count ruined fasteners on one hand and thats because they were garbage product.
One of the things I wrenched on was F-4 phantoms in the navy. I worked on radar/avionics. The radome had to be opened to do nearly anything so it was typical to open and close several every day. They had specific torque values, 165 inch pounds, theres 4 and theyre very complicated. Our standard tool boxes didnt have torque wrenches and it was a pain to have to check one out from the tool corral when you needed one, so our shop chief had a system for QA on that. Once a year or so we all lined up at one of the aircraft, and tightened all 4 fasteners by feel. Any of us that got all 4 within 10 inch pounds of spec would be crew leader and responsible for securing the radome. I had no problem passing that test, and about a third of our shop did it too.
Id still go with a torque wrench on most things, and always use it on automotive work.
I think the most critical time for a torque wrench is assembling high end bicycles. I built an all titanium mountain bike about 15 years ago and used shimanos most expensive components. It doesnt take a lot to ruin that stuff, for instance the chain rings attach to the cranks with aluminum fasteners, I think they were something like 12 inch pounds.
On my 280ah eve cells I used new bolts, cut them into studs and JB welded them to the terminals. The idea of screwing a bolt into that aluminum terminal and repeatedly tightening it didnt seem like a good idea at all.

His comment on broken bolts as i read it had nothing to do with skill in installing the bolts, it had to do with dissimilar metal fasteners locking things together causing locked fasteners and breaking the bolts.

Also, a feel for repetitive jobs doesn't transfer to the same skill assembling electrical gear.

I would have no issue torquing by feel axel nuts aand various assembly systems... electrical panels, battery lugs, and other critical areas, I use a proper torque tool...

 

[timselectric]

I've done everything by feel for 40 years.
The only thing that I use a torque wrench on regularly, are vehicle lug nuts.

 

[Supervstech]

I've done everything by feel for 40 years.
The only thing that I use a torque wrench on regularly, are vehicle lug nuts.

Wild.
That's pretty much the only thing I don't use one on!

 

[timselectric]

Wild.
That's pretty much the only thing I don't use one on!

I should have said , only for aluminum wheels.
If not properly torqued, they will work loose.

 

[Supervstech]

I should have said , only for aluminum wheels.
If not properly torqued, they will work loose.

Oh, absolutely!

 

[Batvette]

His comment on broken bolts as i read it had nothing to do with skill in installing the bolts, it had to do with dissimilar metal fasteners locking things together causing locked fasteners and breaking the bolts.

Also, a feel for repetitive jobs doesn't transfer to the same skill assembling electrical gear.

I would have no issue torquing by feel axel nuts aand various assembly systems... electrical panels, battery lugs, and other critical areas, I use a proper torque tool...

This was what I commented about:

"If you haven't twisted off or stripped out bolts, screws, studs, etc then you haven't ever actually done any of this stuff... So the experienced know exactly what I'm talking about..."

I didnt think that had to do with corrosion which he addressed in another section.

Im not sure what being electrical parts makes fasteners used for assembly unique, a screw being tightened has a recommended torque value whether power flows through it or not.
It simply isnt practical to use torque measuring tools on many assemblies example, terminal blocks with number 8 flat head screws.
Another issue is the proliferation of cheap chinese hardware where standard torque values dont apply.
His comment suggested if people havent ruined a number of parts they had no experience in this field I thought that was silly and stand by it.
However as I said Im not claiming torque wrenches dont have their place.

 

[Batvette]

Wild.
That's pretty much the only thing I don't use one on!

IME torque tools are best on very small and very large fasteners to make sure theyre tight enough and not to prevent breakage.
Interestingly I have clickers in 1/4, 3/8, and 1/2, beam type in 1/4 and 3/8, and last year bought HFs fancy ikon 1/2 split beam thats a snap on clone.(done again Id buy the ikon clicker) So its funny Im arguing I dont need a torque wrench sometimes.

 

[Supervstech]

This was what I commented about:

"If you haven't twisted off or stripped out bolts, screws, studs, etc then you haven't ever actually done any of this stuff... So the experienced know exactly what I'm talking about..."

I didnt think that had to do with corrosion which he addressed in another section.

Im not sure what being electrical parts makes fasteners used for assembly unique, a screw being tightened has a recommended torque value whether power flows through it or not.
It simply isnt practical to use torque measuring tools on many assemblies example, terminal blocks with number 8 flat head screws.
Another issue is the proliferation of cheap chinese hardware where standard torque values dont apply.
His comment suggested if people havent ruined a number of parts they had no experience in this field I thought that was silly and stand by it.
However as I said Im not claiming torque wrenches dont have their place.

Directly quoting the entire paragraph from him…

“
Nothing like having dissimilar metals fuse together in a corroded mess... Twisted off screws, bolts, studs, etc. This often as not results in replacment rather than repair of components since its difficult to impossible to repair twisted off studs, stripped threads, corroded contacts in a lot of components. Wire & cable terminal end replacment is one thing, but do you really want to disassemble an inverter that has epoxy sealer (potting) protecting the circuit board where the terminal twisted/corroded off?

5. Torque Limiting Device, Wrench Or Screwdriver.

EVERY SINGLE THREADED FASTENER has a torque (rotational force) specification for best performance.

If you haven't twisted off or stripped out bolts, screws, studs, etc then you haven't ever actually done any of this stuff... So the experienced know exactly what I'm talking about...”

So… he is specifically talking about corrosion and dissimilar metals …

 

[JRH]

6. Conductor Materials Are NOT 1 Size Fits All...

The best elemental electrical conductors are as follows (and YES, this is 100% scientifically proven fact).

Silver, Copper, Gold, Aluminum, Zinc.

Silver is high conduction for AC & DC, it's low corrosion, and it melts at a relatively low temperature. The properties of silver bearing solder are such the silver moves to the outside of the liquid, so it makes contact with both wire conductor and terminal BEFORE it solidifies. This is the reason I stress SILVER BEARING SOLDER.

In very high amerage/temp situations i keep 'Junk' silver around to make these connections bullet proof. Coating breaker contacts keeps them from welding shut, silver is self healing when electrical arcs tunnel into contact material, it's insanely hard to beat the electrical properties of silver.

Copper is has high conduction properties, is much cheaper than silver or gold, handles DC current well, the reason copper is the choice for most electrical conductors. The draw back is copper is highly reactive to oxygen in the atmosphere so you DO need to protect any exposed copper.

Copper contact WILL weld shut, being crystalline in nature it doesn't heal very well when electrical arcs tunnel into it, etc. Good solid conductor, not so great in high heat (plasma) situation. Silver bonds reduclously well to copper, so silver bearing or silver solder.

Gold, the price, but it's very low reactive with most atmospheric contaminants and has excellent heat properties.

Aluminum is lighter weight, doesn't handle amperage/heating well, but does handle high frequency AC skin effect pretty well. Its thermal expansion rate is twice what steel is

Zinc has excellent electrical properties, but is toxic to handle/work, its also very reactive to atmosphere and surface corrodes quite easily so high frequency AC skin effect applications are almost useless. You might want to keep that in mind if you buy terminals that are zinc plated, while zinc is highly conductive, oxidized/corroded zinc is not.

Iron/Steel is a high resistance material, not even in the top ten best conductors. While steel makes a good fastener, there are better choices for high capacity electrical connections/terminals.

Copper is obvious, but copper bolts stretch, brass bolts are usually 'High Brass' or 'Cartridge' meaning it's a high Zinc alloy, about 70% Copper - 30% Zinc. Another choice is bronze, around 90% copper - 10% Tin.

These all are a lot more conductive than steel. These, with a copper washer, add contact area to your connection by conducting from far side of the cable terminal to the far side of the battery terminal for instance.

Recap... I pay a LOT to make and store, transfer the power around, I don't waste a Watt I can prevent through resistance.

Crimp THEN solder to seal up and make air spaces conductive, protect raw copper conductors. It's BOTH, not either/or.

Atmosphere WILL corrode your conductors. Period.
Doing what is reasonable to promote conduction, prevent corrosion helps you in both the short term, and long term.
Conductive grease, protective dielectric grease, heat shrink, solder 'Tinning' exposed copper will all pay off.

Use highly conductive fasteners. This isn't a high strength, structural situation, this is a high conductive situation.

Contact area is critical to amperage conduction, pay attention to the contact surface area AND the mass of the terminals. Copper washers and silver bearing solder is a good way to make any small terminal surface area larger without excessive resistance. The silver is more conductive than the copper, so use both liberally.

APPLICATION! APPLICATION! APPLICATION!

Good advice… nothin* is perfect but you did a good job… thank you.
J.

 

[webbbn]

What about splicing? What is the current recommended method to splice wire for, say, wiring a subpanel?

How about splicing copper and aluminum? Say you have aluminum wire installed, and want to splice a length of copper onto it, or vice versa. Not only are they different metals, but possibly different sizes. Is that just a bad idea?

Wire nuts never did seem like a good idea, and there are many options now, so what is the best?

 

[Batvette]

Directly quoting the entire paragraph from him…

“
Nothing like having dissimilar metals fuse together in a corroded mess... Twisted off screws, bolts, studs, etc. This often as not results in replacment rather than repair of components since its difficult to impossible to repair twisted off studs, stripped threads, corroded contacts in a lot of components. Wire & cable terminal end replacment is one thing, but do you really want to disassemble an inverter that has epoxy sealer (potting) protecting the circuit board where the terminal twisted/corroded off?

5. Torque Limiting Device, Wrench Or Screwdriver.

EVERY SINGLE THREADED FASTENER has a torque (rotational force) specification for best performance.

If you haven't twisted off or stripped out bolts, screws, studs, etc then you haven't ever actually done any of this stuff... So the experienced know exactly what I'm talking about...”

So… he is specifically talking about corrosion and dissimilar metals …

His sections are numbered. Section 4 discusses corrosion. Section 5 discusses torque limiting devices.

 

[Batvette]

What about splicing? What is the current recommended method to splice wire for, say, wiring a subpanel?

How about splicing copper and aluminum? Say you have aluminum wire installed, and want to splice a length of copper onto it, or vice versa. Not only are they different metals, but possibly different sizes. Is that just a bad idea?

Wire nuts never did seem like a good idea, and there are many options now, so what is the best?

Wire nuts are acceptable for home wiring to code. I wont use them for anything. I solder everything. Even things I maybe shouldnt.

 

[Supervstech]

What about splicing? What is the current recommended method to splice wire for, say, wiring a subpanel?

How about splicing copper and aluminum? Say you have aluminum wire installed, and want to splice a length of copper onto it, or vice versa. Not only are they different metals, but possibly different sizes. Is that just a bad idea?

Wire nuts never did seem like a good idea, and there are many options now, so what is the best?

When splicing aluminum to copper conductors you must use listed cu/al fasteners.
Such as plated split bolts, or coated wire nuts or coated terminal blocks designed for mating the dissimilar metals together.
And the conductors must be sized to handle the same ampacity.
12 al to 14 cu, etc...