TravelScoot wouldn't power up. Battery issue.

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TravelScoot wouldn't power up. Battery issue.

Postby flagman1776 » 05 Sep 2018, 22:44

I set the troublesome pack aside & made it to my doctor's appointment by switching to the official TS LI pack I happened to have with me...
I've had random loss of power events over the 6 years I've been using the LiFePO4 pack. (China, unmarked mongrel cells, reworked for smart charging.) I've had all manner of failures, usually a welded trace breaks. Not totally surprising since the use cycle involves breaking the unit down each time... it's just a lot of handling. I know the pack is charged... I have just 20 minutes of use on it. Have to be careful I don't fry myself!

I brought it it & put it on the bench, got it out of the soft travel case, removed the hard battery support tray & soft polyfoam padding, so I'm down to the pack. I started testing... I got nowhere fast. NO POWER on the Anderson SB50. I actually managed to disassemble the SB50 connector this time without destroying it.
In my efforts to stabilize the 3P7S pack, I had hot glued all the cells possible, duct taped the outside, then 2 layers of electrical tape (black sticky) to cover the contacts... then still more as wrapping to stabilize the harnesses. There was NO movement in the wires at the pack. Rock solid. I spent an hour gently cutting away & peeling the tape with scissors without shorting anything out or cutting the tiny balance leads or pulling them off with the sticky tape.

All I can find is the main power lead positive tests open. SERIOUSLY! It's a big ass wire. How can it be open? But it tests open. It has the Anderson contact soldered to one end. It has a round ring terminal soldered to the other & the ring soldered to the end of the cell. I have power through the ring terminal soldered to the cell. An open wire?

I hate the welded, now soldered tab, cells. I wish I could solder a brass machine screw to the cell, & bolt to it. I didn't have time to test the rest of the traces, but nothing visual. I need to go through the rest of the pack again.
I'm going to have to skin this big ass wire once I get it replaced... so I understand WTF. I'd have never guessed the main power lead itself.
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Re: TravelScoot wouldn't power up. Battery issue.

Postby Burgerman » 05 Sep 2018, 22:49

If a thing can go wrong it will. Several times. Thats my law. I no longer trust ANYTHING. The anderson isnt crimped is it?
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Re: TravelScoot wouldn't power up. Battery issue.

Postby flagman1776 » 06 Sep 2018, 00:29

The Anderson is soldered. The ring terminal was crimped and soldered to the wire & the cell... Yes, I'll peel the insulation away from the terminals & test the solder connections. I'm having trouble believing the wire could fail... but it gets bent regularly in handling. I COULD fatigue fracture over time. It's Marine grade stranded wire. banghead

I can get down the stairs easy enough but takes a lot of energy to get back up them.
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Re: TravelScoot wouldn't power up. Battery issue.

Postby flagman1776 » 06 Sep 2018, 22:28

I cut back the insulation at both ends and discovered all the strands of the wire were indeed broken right next to the Anderson contact just beyond where the solder ended. I didn't find any other faults.
I decided to replace the entire lead. Soldering was a struggle with my hand issues. I needed a "third hand" to guide the wire into the terminal. Ultimately, I used a pair of magnetic retriever tools stuck to my vise to guide the wire straight into the terminal.
I carefully taped up all the exposed contacts & stabilized the harnesses with special attention to the fragile balance wires.
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Re: TravelScoot wouldn't power up. Battery issue.

Postby ex-Gooserider » 11 Sep 2018, 05:21

This is what I was expecting you'd find as soon as I read your description of the lead testing open...

It is the issue that I have argued with BM about on various threads concerning whether or not to solder terminals.... In a crimped terminal without solder, there is a certain amount of ability for the wire to flex at the crimp, although it's still a bad idea, and good practice calls for strain relief...

When you solder the wire, it glues all the strands together into a solid block so that any movement causes the flex to occur right at the point where the wire enters the solder blob - this leads to fatigue failures, like what you encountered.... Since the insulation covers the wire, and gives it some support, the break is hard to find, and often intermittent depending on just how the joint is flexed...

It is worth noting that Anderson does NOT recommend soldering in their technical docs. They DO recommend using their (expensive) 4-dent crimp tool on pins that are sized to match the wire used... Tri-Crimp makes an interchangeable die ratchet crimper that has dies for the SB-50 size pins, that they say meets Anderson specs even though it only makes one dent....

Many of us use the hydraulic hex crimper, which appears to do a solid job, but there is no data about whether or not Anderson would approve it's crimps or not. Another problem we sometimes have is that we are usually using the most common AWG 6 sized pins, with smaller size wire, so how best to make up the difference? BM's solution is to solder, but IMHO that is questionable.

I do currently solder most of my SB-50 pins, but I also make sure to provide robust strain relief close to the connector, so it can't flex. However if I had to do a connector without strain relief, which I understand to be the case with your pack, I would NOT solder... Instead I would do a crimp only connection. If I wasn't using AWG 6, wire, I would stuff as many other stripped wires into the pin as needed to get close to the same volume of conductors in the pin socket as AWG 6 (it fills the socket pretty snugly) and then crimp, trimming off any excess wires afterwards....

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Re: TravelScoot wouldn't power up. Battery issue.

Postby Burgerman » 11 Sep 2018, 09:03

It is the issue that I have argued with BM about on various threads concerning whether or not to solder terminals.... In a crimped terminal without solder, there is a certain amount of ability for the wire to flex at the crimp,


Not if its crimped solidly, it becomes one block. Solid, no way for air to enter. Which the larger sized 16mm2 terminals dont allow due to the wall being too thin. But the same problem applies in both cases. Solder or crimp, should hold all strands totally solid with no movement. Unless its not crimped adequately... So theres no gain here by crimping alone. And in this size with the larger terminal in the anderson 50 crimping alone isnt secure.
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Re: TravelScoot wouldn't power up. Battery issue.

Postby LROBBINS » 11 Sep 2018, 11:27

Anderson does NOT say you shouldn't solder. They recommend crimping, but also provide quite specific instructions for soldering as well as crimping. Here are some quotes from their catalog:
APP® connectors are designed to be crimped and/or soldered to multi-stranded copper conductor wires only.

| Crimping Technical Reference |
Crimping, Soldering, and Assembly Best Practices. Instructions for proper assembly are available for each connector
and should be followed. These best practices are for reference only.
Stripping Wire Insulation
Problems with cable harness and connector systems often begin with improper or accidental cutting of wire strands when stripping
wire insulation. Each strand is important, and all of them must be included in the contact barrel to avoid unnecessary hot spots
during later operation. When removing insulation, position a sharp blade at a right angle and apply a steady controlled pressure
cutting only the cable insulation and not the copper wire strands. Wires should be stripped to the lengths specified in the specific
connector assembly instruction.
Cleaning Copper Wire
Copper oxide, a non-conductive material accumulates on copper wires exposed to oxygen and moisture. Aged and badly
tarnished copper wire needs to be thoroughly cleaned to realize the rated performance of the connector and wire. Heavy
oxidation can be scraped off with a stiff wire brush that penetrates the entire bundle and cleans every strand. For light
surface oxidation a 3M Scotch Bright™ pad is recommended. The wires are ready for insertion into the contact barrel
when they are burnished to their original bright copper finish. Contact barrels are lined with silver or tin plating to assure
consistently high conductivity which will be reduced if the barrel is crimped around aged or tarnished wire.
Crimping
APP® connectors are designed to achieve the highest levels of durability, reliability, and performance as shown on the connector
data sheets. Crimp tooling is a critical link between the designed performance of an APP® connector and the realization of that
performance by our customers.
As part of the connector design and testing process, APP® recommends a limited number of crimp solutions that have proven to
deliver the intended connector performance in a process that is repeatable. Only these solutions tested by APP® are listed in the
conditions of acceptability from safety agencies such as UL, CSA, and TUV.
Use of tooling solutions not tested by APP® can affect not only performance but also safety agency approvals. Problems attributable
to use of tools not recommended by APP® include:
Electrical and Thermal
• High electrical resistance
• Failure to realize designed current and voltage carrying capability
• Overheating
• Melting of connector housings
Mechanical
• Contacts not able to fit inside connector housings.
• Contacts not seated properly in connector housings causing: shorts, intermittent circuits, abnormally high or low mating and
unmating force, & low retention force of the contact in the housing
All Data Subject To Change Without Notice www.andersonpower.com - 99 -
SECTION 4
Tooling
Soldering
The alternative to crimping is to solder all cable strands within the contact barrel. When using an open flame, make sure that you
are not in an area where explosive gasses are present. The right proportion of solder is essential if this procedure is employed.
Use a quality 60/40 solder (60 percent tin, 40 percent lead) in wire form with a rosin flux core. Cable strands should be separately
fluxed with rosin paste, and the contact should be held in a vise with the barrel end facing up. Apply heat to the outside of the
barrel while the solder flows in beside the wire strands.
Here are some things to avoid when soldering:
A. Don’t use too much solder, to the point that it flows out of the contact barrel.
B. Don’t allow flux or solder on the outside of the contact. This will interfere with contact mounting within the installation or
with the contact connection to a mating connector.
C. Don’t overheat and cause excessive solder to “wick” up into the cable and stiffen it. This could interfere with contact
flexibility when connectors are mated.
D. Don’t solder when contact is in the connector housing. Solder away from the housing and then insert the contact into the
housing after it has cooled.
NOTE: Underwriters Laboratories (UL) requires the use of a cable clamp for soldered connections to unsupported wires.

If you don't have an Anderson crimper, and especially if using the thin wall terminals, crimp + solder is the better way to go, but it is also important to do the soldering the way Anderson describes to avoid running solder back into the unsupported wire outside the terminal. (And note the UL requirement in the last line - some sort of mechanical support is a good idea to avoid problems just in case solder has gotten up into the wire past the terminal barrel.)
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Re: TravelScoot wouldn't power up. Battery issue.

Postby flagman1776 » 11 Sep 2018, 19:34

I thank everyone for their thoughtful advise. A lot of good information.
I think the original solder connection might have not been as straight into the connector as desired. The result was the wires didn't bend "together". Indeed the intermittent connection as described above was driving me CRAZY!
As the instructions specified, I do use wood insulators to hold the contact upright in my vise. A fairlead fixture to steady the wire straight into the barrel would be a big advance. Maybe something with guide hole(s) that secures to the vise with a magnet or a layer of wood insulators might be extended to form this. (Surely others have plywood saddles that sit in their vise jaws to avoid damage.)
Because it's necessary to disconnect with every use, a strain relief isn't practical. I lost sight that flexing of the wires will fatigue the cable eventually.
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Re: TravelScoot wouldn't power up. Battery issue.

Postby LROBBINS » 11 Sep 2018, 20:43

After fitting the contacts to the connector, you can fill in around the wire with Goop. Once hardened it will keep the wire from flexing near the contact, but it can be removed pretty easily by heating to ca. 100oC and using a pair of needle-nosed pliers. (I use a hot air soldering wand to warm up industrial Goop when I need to remove it.)
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Re: TravelScoot wouldn't power up. Battery issue.

Postby flagman1776 » 14 Sep 2018, 15:53

This discussion has convinced me that I need to make new (and better) pads for my vise jaws, including an extended one with provision to support my wire "straight in" when soldering Anderson connectors. I need to make it NOW, not when I have a project on the bench. This will improve the quality of my work.
Did I mention, mid solder job... I dropped the HOT soldering iron out of my weak hand. I was relieved it missed my leg. That night, I discovered it hadn't missed my belly! +*&^%$#!
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Re: TravelScoot wouldn't power up. Battery issue.

Postby Burgerman » 14 Sep 2018, 17:48

Theres your problem. Soldering iron.

Use a correct sized anderson connector, not one thats too big. So the wire is a good push fit. Flux LIGHTLY. And if theres space add two bits if resin/rosin cored solder and crimp it if possible. If you dont have a correct sized connector, you MUST crimp as you should not be filling space with solder! Heat the joint with a flame from one of these:

https://www.amazon.com/Turbo-Blue-Refil ... refillable

The moment the solder melts, give it 1 extra second and stop straight away, and dip in water. The whole process should take 5 seconds. And should be clean. No insulation should be melted ordamaged. While its warm grab the insulation and push it up to the oldered joint so theres zero gap. The wire should not ever be able to be anything but perfectly straight if you use the correct sized connector. Or crimp. You dont need anything extra to align it.

You are making a simple process that should take seconds into something complex. The solder only wicks up the wire if you heat too slowly and the heat transfers up the cable. And so the cable gets it too hot. Dont give it time.

THIS is a too small 6mm2 cable, in a too big 16mm2 connector. Since I have a lot! So it had to be crimped. http://www.wheelchairdriver.com/crimp-solder.htm And never had one fail in 21 years of making rather a lot of these!
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Re: TravelScoot wouldn't power up. Battery issue.

Postby Gnomatic » 14 Sep 2018, 20:33

I recently sold one of my old chairs to another member here. Before having it loaded up on a pallet and packed to be shipped I decided to remove the batteries. As I did, one of the battery lugs just fell off the 6 AWG wire. It was factory wiring and had been crimped on. Very poorly. :fencing

After making several cables up for this or that using the method espoused here - using an an hydraulic crimper and torch to melt the solder etc. ect. - I can't get over how bad the crimp jobs are on most factory wheelchair wiring. Many with bare wire exposed and no heat shrink. Its easy to it right and takes so little time. :ak47
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Re: TravelScoot wouldn't power up. Battery issue.

Postby LROBBINS » 14 Sep 2018, 22:29

You're not the only one with that experience. Rachi has had two power chairs (four if you count one cannibalized for parts to keep the 1st one going, and the one she now has that has almost nothing of the original chair left) in 28 of her 32 years. On both of the factory chairs, from two different factories, all, 100%, of the crimped connections fell apart - or rather when one wire fell out and I tugged on the others, they were all so badly crimped that they came right out. The second chair also had 100% cold solder joints in the lighting loom and XLR plug that connected wires with no stress relief and with the insulation pared back to 1/4 to 1/2" past the terminals. That second one also had one motor with a brush holder making only intermittent contact - not just arcing, but actually giving no contact at all. Both were made in English factories (and the bad motor was also an English product) that obviously had never heard of Good Manufacturing Practice. I haven't seen anything that bad on the stuff I've bought from China.
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Re: TravelScoot wouldn't power up. Battery issue.

Postby Burgerman » 14 Sep 2018, 22:51

Unless on small wires, or using heavy walled connectors and industrial quality crimping, theres no alternative to soldering for strength, reliability etc. But it must be done reasonably right. The thing is that its *easy* to solder right, if you have had even a few hours of practice. As an ex plumber thats not really a problem for me. But I tought a 14 year old girl to use solder(s) and a gas flame, and a soldering iron, to solder, braze, etc in a couple of hours. She wanted to make jewelry etc. A few notes, a little hands on practice, and some advice. Done. She can do a better job fitting a 25 pin subD connector than I can now. In minutes. Her eyes still work :fencing Look at Expresso, he never saw a soldering iron, new he's neater than me.

Crimping to be reliable needs everything in its favour.
CORRECT sized, type and correctly stripped cable.
Correct sized any type of crimp connector, not the thin walled rubbish thats commonly available.
Correct fine tuned technique, that excludes all air so no oxydisation, and solid contact with no movement. Needs a QUALITY cripmp tool and quality crimp terminal. Not made from a bit of thin copper tube and zinc coated...
Making a stock powerchair a unreliable fire hazard...

Soldering on the other hand is relatively tolerant. If it looks right, is shiny, and smooth, and if you do it fast so it doesent wick up the wire or melt insulation, then its good. Only a bit of practise needed.
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