Charging cable has died!!!

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offgridQLD
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Charging cable has died!!!

Post by offgridQLD » Wed, 25 Feb 2015, 14:23

Regarding the dielectric grease.

I was watching a Utube video where John Hardy is testing Calb 40Ah cells. This particular test rig experiment was testing cell performance (or capacity loss) slow charging vs fast charging. Anyhow he was reporting on his results at 500 cycles.

Link to the relevant section of the video where he comments on issues he was having using dielectric grease.

link should start from the relevant section. If not 54:33 is where to start watching.

https://www.youtube.com/watch?v=c-g6FV8gqC8#t=3274

I have just taken note of his findings but not sure where I stand on it.

Kurt

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Post by Adverse Effects » Wed, 25 Feb 2015, 14:25

LOL that is the same vid i was lookin for about the same thing you showed lol

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Post by Johny » Wed, 25 Feb 2015, 19:58

I'm convinced guys. I'll get some Ferrules before my "next event".

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Post by Richo » Wed, 25 Feb 2015, 20:37

T1 Terry wrote:I'd certainly spend the extra $$ and few seconds to crimp the ferrules properly, it does make a much better connection.


I have one of the pneumatic bootlace crimpers.
One job 640 bootlaces... Image

I like the iris one from Altronics for the odd bootlace
http://www.altronics.com.au/p/t1547-cri ... e-ferrule/

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Post by T1 Terry » Thu, 26 Feb 2015, 01:47

I like the smaller hexagon crimpers as well

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Post by Johny » Thu, 26 Feb 2015, 15:15

Terry, have you used the one (or similar) you linked to or is that just an example? Most of my requirement would be for 1.5mm^2 cable so I don't see a ratchet type as necessary. I also won't be doing that many.

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Post by weber » Thu, 26 Feb 2015, 19:38

I think crimpers for bootlace ferrules are snake-oil. Sure, if you enjoy seeing the hexagon, or any of the many other pretty shapes available, just before you squash it flat in a screw terminal, go ahead. There's no harm. Or is there? I can't help wondering if some shapes, e.g. square, rectangle and wavy-rectangle, could resist squashing initially, but slowly have their sides bulge over time, allowing the strands inside to spread, thereby relaxing the pressure in the joint and defeating their purpose.

And don't be tempted to solder ferrules after crimping, unless it's also after they are clamped in their final resting place. It's not the same as soldering a proper crimp lug after crimping.

What could be a better crimper for bootlace ferrules than a pair of pliers? It produces maximum strand-spreading from the start.

BTW, I realised there is a reason to call them "bootlace" ferrules. There is another kind of ferrule used in electrical termination -- the ferrules used with RF connectors on coax cable. These connect the braided outer conductor. They certainly need proper hex crimpers.

Here's an idea that was phoned in by Jeff Owen. Crimp some fork lugs onto the wires and then clamp the forks. Of course you do need a proper ratchet crimper for those. I could only find a grungy old plug and fork lug with which to test the idea. I recommend cutting the insulation back to half on the crimp lug before crimping, unlike what you see here, which is a bit too high. You can also solder the wire inside the crimp, after crimping, and use jointing compound or dielectric grease (a thin smear only) on the fork before clamping.

Image

It still needs attention to detail however. You have to hold the fork jammed towards the right-angle in the movable clamping plate while tightening the screw, otherwise you end up with one tine of the fork waving in the breeze, and then the plates will not be parallel and the fork will slowly "ooze" out of the wedge-shaped gap over time -- what I call "failure by wedge-creep".

In fact it's still not right in the photo. The fork should be leaning over to match the angle of the movable clamping plate, which inevitably ends up where you see it, due to the direction of rotation of the screw.

Jeff also thought we might be able to use a ring lug instead of a fork, for greater security, but the ends of the screws are swaged so they are captive.

Jaycar have them,
http://www.jaycar.com.au/productView.asp?ID=PT4623
and a ratchet crimper for them
http://www.jaycar.com.au/productView.asp?ID=TH1829
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Post by Richo » Thu, 26 Feb 2015, 20:21

Yeah the fork would be a good alternative. Image

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Post by Johny » Thu, 26 Feb 2015, 20:28

With a bit of TLC you could use a ring lug but cut it at the opposite side to the crimp then force it into the wedge and use pointy nose pliers to close it again. I think I've done that somewhere....

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Post by weber » Thu, 26 Feb 2015, 22:42

Ah yes. The ol' turn-a-ring-into-a-fork-with-the-sidecutters trick. I would never do anything so crude. Image OK. I'm lying.

That should work just fine. In fact, with the fork, it would be a good idea to go part way to doing the reverse trick. i.e. the ol' turn-a-fork-into-a-ring-with-the-pliers trick, as you will see (not done) in the photos below.

You can see I've cut the insulation on the crimp, back to near the metal. That's to give enough room for the wires to exit when the cover is on. I think this is an old Clipsal plug. Oh, and you see that thing in the picture that is so amazingly thin that it's "no thicker than a human hair" ... It's a human hair. Sorry.

Image

And here's the back side, showing why you have to ensure that the fork rotates with the nut. Yes, a plug was injured in making this picture. In fact, it had to be put down.

Image

Jeff phoned again, to say he'd found an uninsulated fork, and it worked even better, because it's not so tall. But he pointed out it needs a different crimper and he supposed that the same result could be obtained by cutting back the insulation on the kind I'd shown.

Then the conversation went something like this.

Jeff: I went and looked at some of those bootstrap things. They're round! It's all wrong. The fork is obviously better. You'll get much more contact area. And with the ferrule you'll still get death-by-wedgie!

Dave: The fork is good, but the ferrule is only thin and so it doesn't stay round, it squashes flat. In fact I suggested squashing it flat with pliers first.

Jeff: Ah, I didn't realise it was thin-walled. I say squash it flat with a hammer!

I love Jeff's "death by wedgie". In fact death occurs because any wedgie will spontanously unwedge over time. And yes, with the ferrule, you still have to ensure it is laid in the corner of the nut to avoid death-by-wedgie, and then it ends up with hardly any of it being clamped, due to the nut rotation. So I think I'll "use the fork, Luke" in future, except for extension sockets where you don't have the option. I'll continue to "go ferrule" there. Image

Here's another important wire termination rule I was reminded of in my reading.

Don't twist wires before crimping them, or before putting them in a ferrule.
Or at least, use the absolute minimum twist that lets you keep the strands together while you're getting them in. Usually the slight twist that the wire manufacturer gives is sufficient. But if you can, undo even that twist, before crimping.

Why? Because when you twist a wire it gets shorter and fatter. If you crimp it while it's fat, and then you untwist it, perhaps accidentally while installing it, it will get skinny and won't be crimped any more.

But, you say, if it's tightly crimped, how can you untwist it?

The untwist starts at the outside and propagates in. The progressive skinniness allows it to do so. Try it some time. Crimp one while tightly twisted, then pull it while untwisting.

[Edit: Reverted "death by un-wedgie" to "death by wedgie".]
Last edited by weber on Thu, 26 Feb 2015, 11:56, edited 1 time in total.
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Post by offgridQLD » Thu, 26 Feb 2015, 23:54

Not the easiest to achieve in the field but...

Ultrasonic welding of the wire directly to the pin would make a good connection low resistance permanent connection that wont come loose.

Most critical terminals Aerospace, medical and even critical Automotive, terminals like airbag wire terminals are fixed this way. The wire and the terminal become one.

Finding a extension cord with wires terminated by Ultrasonic welding would be nice.

Or you can purchase your own for about $700 on ebay.

Kurt







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Post by weber » Fri, 27 Feb 2015, 00:28

offgridQLD wrote: Regarding the dielectric grease. I was watching a Utube video where John Hardy is testing Calb 40Ah cells. ...

Link to the relevant section of the video where he comments on issues he was having using dielectric grease. ...
https://www.youtube.com/watch?v=c-g6FV8gqC8#t=3274

I have just taken note of his findings but not sure where I stand on it.

Here's some of what John Hardy says:
And you can see that there's a little bit of temperature difference between them. ... We're only talking about a degree or so. ... And the difference between those two is simply I'd cleaned off some dielectric grease. When I first assembled the pack I used dielectric grease on all the high current connections and the effect of that was actually to increase resistance. I'd hoped to make things a little better by excluding corrosion and so on but the grease actually increased the resistance of the connection. So I shan't be using it in future. And simply cleaning off the grease resulted in a noticeable drop in temperature.
Notice that he used dielectric grease on _all_ the terminals but only two were showing slightly higher heating than the others and they improved when he cleaned off _some_ grease. In any case, he would have needed some pretty nasty solvent to clean it _all_ off, being silicone-based.

This suggests to me that he simply put too much on those two terminals to start with, and so it was not fully squeezed out, i.e. it was still filling more than just the voids when full torque was achieved. I suspect if he had just re-torqued them now that they'd had time to flow out, they would have been fine.

But it's a good reminder that we should use only a thin smear.

If you use it you might have slightly higher resistance initially, but that will be more than repaid, some years down the track, when the unsealed joint corrodes.

I find it kinda cute when Americans and Brits try so hard to be all up-to-date and metric by using "degrees Centigrade", when that actually went out with Brylcreem (in 1960). It was the Beatles that killed it off -- Brylcreem that is, not Centigrade. Image

And no, I'm not suggesting you use Brylcreem as dielectric grease ... although ... who knows. Image

Anyway, with dielectric grease or jointing compound, "A Little Dab'll Do Ya!"

[Edit: Removed "John hardy wrote:" from quote box.]
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Post by offgridQLD » Fri, 27 Feb 2015, 01:17

Could be though only 1/2 the cells where high current. Key could be in the wording. I will just ask him and clear that one up.

Yes I agree to much would be a issue.

Kurt

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Post by weber » Fri, 27 Feb 2015, 02:40

offgridQLD wrote: Could be though only 1/2 the cells where high current.

No. He says that after 500 cycles he swapped packs, so they each get a turn at being fast-charged. And that would be "high current connections" as opposed to voltage sensing connections.

Edit:
In any case, he says that the graph shows the 6 terminals of the cells that were being fast charged. So they had all been gooped (technical term), but only two of them would briefly go 4 degrees higher than the others before stabilising at the same or lower temperature than the others.
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Post by weber » Fri, 27 Feb 2015, 04:13

And besides, you'd have to be certifiable not to use some kind of jointing compound or dielectric grease on the cathode (positive) terminals as these are aluminium.
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Post by coulomb » Fri, 27 Feb 2015, 04:16

offgridQLD wrote: Or you can purchase your own for about $700 on ebay.

I hope that's for a complete welding machine, not one power cord! Image
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Post by offgridQLD » Fri, 27 Feb 2015, 12:48

He has only completed 500 cycle's. Though I agree looks like 3 cells in each test and o only 2 with higher temp.

I used the grease (as you know ...thanks) and just a smear and it's all working fine. Though another system I am following he elected not to use it. Almost two years in and no issues. I did question the decision though he said he is monitoring it. The results will be interesting.

Yes $700 was for a 2nd hand industrial machine. Though you usually need to make up the appropriate tooling for the parts your trying to fuse together.

Kurt
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Post by weber » Fri, 27 Feb 2015, 19:31

offgridQLD wrote: He has only completed 500 cycle's.
No. He says (51:20) "What I did at cycle 500 was I stopped the process, discharged the packs to about 2.7 volts per cell. ... What I've now done is I've restarted the tests. I'm running from 500 and I plan to go out to about 1000 cycles. But this time what I'm doing is I'm fast charging Pack B ..."
Though I agree looks like 3 cells in each test and o only 2 with higher temp.
He clearly says there are only 3 cells in each pack. But it's not 2 cells with higher terminal temperature, but only 2 terminals (out of the 6 terminals of the pack that was being fast charged). They happen to be on different cells.
I used the grease (as you know ...thanks) and just a smear and it's all working fine. Though another system I am following he elected not to use it.
Is this like the anti-vaccination or anti-flouride thing? Thousands of engineers attest to what eventually happens when you don't use anti-oxidant on aluminium connections, but one guy in a video makes an off-hand anecdotal remark based on no real evidence and people stop using it in droves?

I've said or implied this before: EVTV contains much that is mere opinion, masquerading as fact. John Hardy's experiment seemed well designed to measure capacity loss from fast charging, but it was never designed to measure terminal connection resistance, and so there are way too many uncontrolled variables for him to really know why those two terminals went 4 degrees hotter, and strangely only during the ramp-up period, not during the steady state.

[RANT]Stuff like anti-vaccination and climate-change denial makes me think that, as a species, we deserve to go extinct. But then I think hey, why can't just the religious nutters, the anti-science types and the narcissists go extinct? Scientists and engineers have been keeping those types alive for more than a hundred years now, and what thanks do they get?[/RANT]
Almost two years in and no issues. I did question the decision though he said he is monitoring it. The results will be interesting.
So how is he monitoring it? Logging terminal temperatures or voltage drops and comparing copper terminals with aluminium ones? I'd love to see the data.

[Edit: Punctuation]
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Post by offgridQLD » Fri, 27 Feb 2015, 20:32

"
Is this like the anti-vaccination or anti-flouride thing? Thousands of engineers attest to what eventually happens when you don't use anti-oxidant on aluminium connections, but one guy in a video makes an off-hand anecdotal remark based on no real evidence and people stop using it in droves?

I've said or implied this before: EVTV contains much that is mere opinion, masquerading as fact. John Hardy's experiment seemed well designed to measure capacity loss from fast charging, but it was never designed to measure terminal connection resistance, and so there are way too many uncontrolled variables for him to really know why those two terminals went 4 degrees hotter, and strangely only during the ramp-up period, not during the steady state."


I'm not quoting anything as fact. Regarding the science behind anything. I find often proving or seeing something being proven to be wrong can help me understand something. Isn't that what science is about even if you prove something is nonsense then thats a outcome. I agree show me why and how and prove it ...bet still let me prove it to myself (sinks in better that way) and I don't have a issue believing it.

I mentioned the response I got from the guy in NSW who didn't use any lithium greases. Not because I thought it was the new (hearsay fact) I was surprised (as it come from someone who usually has a very level headed scientific approach to most things) . Though I am interested to see the outcome. It's not my 10k of batteries so why should I argue.

I don't think he has any sophisticated way of monitoring it other then he is conscious the terminal isn't protected and awaiting the outcome. At least then if someone asked if they should use the grease. I can say yes. If they ask what happens if I don't . I can tell them ...well after about 3 1/2 years your aluminium post will get so corroded that ..... At least I will have a case example for them Image

The only time my thinking skews a little when some one tells me something is bad and the results are negative and proven. If science has proven it so I wont argue with it at all. Though I like to know how bad and what is the outcome with some kind of number guideline to go with it.

For example. Not removing the flux from a copper pipe join in your home will result in corrosion at the joint. It's bad and you will end up with a leaking pipe in your home. Ok I agree with this and we could leave it at that.

But then I start thinking how long will it take to corrode through the pipe and start leaking. Then I start looking at examples of this on 50 year old homes. it's all green and corroded and looks bad) But its not leaking ....yet.

So yes personally I like the proven scientific approach to life ...I'm not religious at all and everyone is vaccinated in our house. Though I don't like just knowing something is bad or true without understanding the impacts of it. Preferably with some numbers behind it so I can judge the risk or plot the outcome and gauge the effects rather than a yes or no answer. Sometimes the effects are there and perhaps negative but not worth worrying about or lost in the roundings.

Though if you can cover your self with a simple step like removing the flux or a smear of grease then why not.

I would have to agree I don't follow along with Jack R and his unproven ideas. Though I wouldn't bundle all of the people who contribute video to his show under the same category. I don't mind the show for it's collection of EV related material and pick the bits from it I want from it. Material is a little thin. Unless some one want's to start a Au EV show Image

Kurt

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Post by T1 Terry » Fri, 27 Feb 2015, 20:40

Johny wrote: Terry, have you used the one (or similar) you linked to or is that just an example? Most of my requirement would be for 1.5mm^2 cable so I don't see a ratchet type as necessary. I also won't be doing that many.
I use the hexagon crimper for up to the green collared size terminals and the square crimper for the brown and white terminals. The white terminals fit 6 B&S sized cable of 4 x 6mm auto cables bunched together.
I also use one of these ratchet crimpersfor jobs that need a flat ferrule rather than a rounded ferrule. A flat ferrule is useless in the likes of a neutral block etc.

I think you would need to actually use the ferrule and crimper method before you could critique it to gain a non biased appraisal.....   Image   Image

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Post by weber » Fri, 27 Feb 2015, 20:57

Sorry Kurt. I thought you'd realise my comments weren't directed at you at all (since you used jointing compound), but to "the guy in NSW". I thought you'd implied he'd left it off because he saw that EVTV video.
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Post by Johny » Thu, 03 Sep 2015, 22:47

Duh! This went yesterday.
Image

This has been replaced by soldered/heatshrunk permanent connection.
Image
It's the stranded & wedge connector issue again.
Strands + wedge connector + humidity(winter) + oxygen (not sealed).

The only reason I noticed it was the other end. I noticed it was discoloured - factory crimped.
Image

I unplugged the cord to replace the socket end and almost couldn't get the plug out.

I have used ferrules on the socket end this time. I have also ordererd a Clipsal 438/15HDTS (240V socket end Heavy Duty Transparent).
My plan is to use ferrules then fill it with transparent silicone.

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Post by offgridQLD » Fri, 04 Sep 2015, 05:02

Yes, it's a great example. Lucky it was just some slumped plastic and nothing more.

Kurt

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Post by RichW » Fri, 23 Oct 2015, 05:18

Re the problem charging cable.¬¬
This is a problem that could have stemmed from a cross-wired active to neutral. The plug base is burned on the active pin but the burnt wiring on the plug is on the neutral wired pin. Another member pointed this out fairly early in the forum discussion. The problem becomes higher level in that control equipment is often operated only via the active terminal. This means that (often) problems arise from switching that remains active or at worst inoperable. On a high power EV charge circuit it could result in overcharged batteries and overheating of wires, batteries, or nearby component or other appliance damage or a live household neutral line and at worst, a fire.

You are taking big risks insurance wise by doing your own wiring. If you are not classified as “proficient” and a fire results you will not have any claim upheld if you stuff up the wiring. As a kiln builder and teacher at a teacher’s college we had a burn out of a $6000 pottery kiln. Tracing the cause I found that a staff member had rewired an extension cord and reversed active to neutral on one end and attached this to another appliance on the same circuit. Temperature control gear on the kiln was upset and remained active after temperature was reached. The result was molten pottery flowing to the steel base of the kiln dissolving kiln insulating bricks in their path until the electric elements final melted also (at 1350’C). I presented the cut-off cable to the elderly staff member and suggested she give any cords to me for repair next time (I held a cords and plugs license for many years before this incident).

A second aspect of this plug problem has been pointed out by some but other issues are at play here. The burning indicates arcing and suggests as others have stated that cable wires have worked loose. Even a slight gap at charging amps for your EV will produce arcing and like an arc welder this will generate heat and melt solder and soften copper wires leading to more heat. As a kiln builder and using electric motors for equipment I was very aware of poor wiring of plug tops (the part with the plug pins). This is the end that gets more movement within the plastic enclosure translating to pin and wire movement relative to each other.
My solution was simple. Ensure you bare enough wire to wrap around the clamping screw to stop the “wedge creep”. (Good term – describes the fault very clearly). I cut the plastic insulation very carefully to ensure no individual wires are cut (I usually use my front teeth so there is no risk of severing cables) twist these wires carefully with some old pliers without sharp grooves and edges to ensure a solid bunching and bend them into a circular end. Carefully feed the end around the securing screw. You will need to open the clamp to the maximum without losing the screw and unsettling the wire twist. It is also important to follow the clamping twist of the screw and its plate and not put it in the opposing way to the tightening direction. That ensures the wire is bound tightly into the screw rather than towards the outside which opens up the cable twist.

Cable length is also critical and if not spot-on any excess cable will not clamp correctly with the cord “nut” or too tight will put a wear point onto your twisted wire attachment. Plug tops are set up for equal length cable stripping at the ends and a specified overall length for free cable without the outer insulation. Packets generally show these dimensions for each type of plug top at purchase, so check your packaging. By the way, stripping the outer cable – mark where the cut is needed (a fine ink pen is handy) and slice along the cable between two conductors avoiding cutting the third. Cut the insulation at right angles when you get to the right place. Don’t overcut for length or your plug top will be too sloppy when the holding nut is screwed down.

If you are unfamiliar with the pins the way I was taught was:-
     Looking at the face plate of the base – Earth pin at the base –
          Top left   ACTIVE (Brown or Red)              /
          Top right NEUTRAL (Blue)                    \
          Bottom    EARTH    (Green or Yellow)              !
i.e. A N   E going clockwise.
Work the Plug Top (pins) to this configuration by placing the plug top in front of the baseplate to check they will match when you plug them in. You can label the base to check and wipe off after wiring just to be sure.

Wiring is an area that can often create problems that you don’t want.
Trick is …. If its not done right .. redo it until it is.
If you are not qualified at least you can check the workmanship!
Hope this helps a bit.
Over described maybe but that’s the teacher coming out. Spent over a decade building gas kilns (licenced Gasfitter – still) and pottery equipment and never had a problem from poor plugs or cords installation using this technique.
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Post by RichW » Fri, 23 Oct 2015, 05:28

Regarding slicing the outer cable I forgot to mention this is with a pair of side-cutting pliers rather than a blade. Also trim off the cord outer using the side cutters. May look a bit ragged but there is little chance of cutting into soft conductor copper wire. RichW

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