90% of my ebike issue come from the wires

[cwah]

My ebike usually fail when...
- I plug the wires incorrectly, such as doing reverse polarity, that killed a controller and a DC converter. Quite an instant death!
- My small AWG 24 snap because of a small pull... Had my speedometer that has its wires snapped so many times, my light snapped, my throttle snapped, my lipo balance wire snapped...
- Vibration makes the soldered wires or wires connections loose.
- Worse product ever I invested in are these bullet crimp terminals: bullet crimp terminal | eBay They always come loose and have so high resistance. I had so many wiring issue with these terminals...
- And recently my hall sensors wires failed when I was 15 miles away from home. I had to take the train to go back home..


So, basically, 90% of my ebike issues come from wiring. Especially these tiny 24AWG wires that are everywhere (speedometer, hall sensors, cycle analyst, throttle, etc etc.)

Now I put a huge amount of solder on these wires to make sure they will stick on the connector, then use my glue gun as first layer of protection and wrap everything with a glue lined heatshrink as secondary layer of protection.


Do you also have the same issues or am I doing a bad job with my wires?

 

[shemozzle999]

Hence the sayings "you’re only as strong as your weakest link" and "the devil is in the detail"

You must ensure you pay attention to all items required on a self build to ensure a reliable outcome.

Also on the Brompton build, double check the cables before terminating them as they move an get stretched during the folding process and allow extra length for movement, the usual cause of wiring failures on my Bromptons.

 

[Deleted member 4366]

You're going through the same process as what many manufactuters go through; From experience, you learn about quality and failure modes; then you make improvements and counter-measures to reduce problems in the future.

Both copper and solder have very low fatigue resistance, so you have to stop all movement and vibration near the joints. Try and lay the wires flat and tape or tie them down if you can. Use heatshrink tube right over the joint if possible. Don't crimp wires - always solder.

Lastly, always tin parts first before soldering and keep the iron on until you are sure the solder is properly wet and soaked in to whatever you're soldering. When you solder joints, always leave the iron on for several seconds after adding solder (except very small components) and leave the iron on until you're sure that the solder is wet. Solder will melt at a relatively low temperature where it'll sit in blobs on what you're soldering without bonding. It needs much higher temperature to go wet and properly join to whatever you're soldering, and if components have a lot of metal in them (high thermal capacity), they take a lot longer than the solder to heat up, so be patient: Both solder and components have to be at high temperature to get a good bond, which is about 370 deg C compared with melting temperature of about 180 deg C. The mistake most people make is that they melt a blob of solder onto a joint at not much more than 180 deg and think it's bonded.

 

[Geebee]

I would say you are doing something wrong or have been very unlucky.
I have built several ebikes and owned a couple of Chinese ones.

One had a power wire connector fail twice in a few thousand Km's so I soldered it and no more trouble, I had a couple get warm at the motor to ESC joints so soldered them to remove the slight resistance in the connectors, that is pretty much all the issues other than fuses in a lot of years and Kilometer's.

No wire should have tension on the connector when mounted, never pull on the wire only the conector.

 

[NRG]

re soldering: also do not move the joint as the solder cools, theres a paste like stage between the solder being molten and solid. Any movement at this point will make a poor joint that will fail at a later date...I would also recommend the use of a true eutectic solder or one that has a 2% silver content.

The silver wets the joint better and minimizes the length of time the solder is in the paste like state (eutectic)

 

[flecc]

As above, and don't let the solder run away from the join along a multistrand flexible wire. That creates a rigid extension away from the joint which greatly increases the incidence of breakage by removing the flexibility. So use a hot enough iron to achieve rapid spot heat for a satisfactory join that doesn't spread solder. An inadequate iron is a very common cause of poor joints.

 

[hech]

.I would also recommend the use of a true eutectic solder or one that has a 2% silver content.

The silver wets the joint better and minimizes the length of time the solder is in the paste like state (eutectic)[/QUOTE]

I have found soldering to be quite a frustrating process especially with large diameter cable (8awg) and my favourite XT60 connectors. Keep thinking I need better solder or a more powerful soldering iron but suspect that patience and a clean iron are the most important missing ingredients.

 

[Scimitar]

I'd also dump the bullet connectors and use something decent instead. They're designed for 1950s cars, not modern ebikes, and they're taking motor phase current. Also, there's nothing wrong with crimps if you use the proper tool, properly, which most people don't.
Soldering is fraught with difficulties until you get the hang of it and most of the troubles have been dealt with by other respondents. There is one thing I always avoid - soldering in a high vibration environment - it leads to failures. I never solder any car or bike connectors for exactly that reason, but an e-bike is much less harsh.

 

[cwah]

Thanks for the insight guys.

1. Always make sure the solder, wires and connectors are all on the same temperature for soldering
2. Always tin the wires
3. Make sure no movement happens during the solder solidification process. I've noticed that when you're moving the solder takes another whiter colour. When I see that I just solder again
4. Don't put solder everywhere on a multistrand wire

I'm applying most of these already hopefully!

My main issue is that I have so many little wires everywhere. For example for my light and flasher I have so many:

Here the 3 wires from my flasher:

I glue gun them and protected the top part with glue lined heatshrink, but they are still very weak and can be killed anytime. I probably have to wrap that with a complete heatshrink.

 

[cwah]

The small wires coming from my flasher with a layer of glue gun protection...

It always feels like if I don't protect these mini wires with at least 1 layer of heatshrink, it's just going to snap from any bad pull

 

[cwah]

I'd also dump the bullet connectors and use something decent instead. They're designed for 1950s cars, not modern ebikes, and they're taking motor phase current. Also, there's nothing wrong with crimps if you use the proper tool, properly, which most people don't.
Soldering is fraught with difficulties until you get the hang of it and most of the troubles have been dealt with by other respondents. There is one thing I always avoid - soldering in a high vibration environment - it leads to failures. I never solder any car or bike connectors for exactly that reason, but an e-bike is much less harsh.

I think crimping can be good for wires under 14awg. I've never seen good crimp on small wires. They are so weak. Just pull and they die. I tried that, and that was my most painful moment with crimping.

Try crimping 20AWG wires, you'll see how weak are the connections.

 

[NRG]

You need a very good crimp tool on wires that small and its important to crimp the insulation material as it provides stress relief. Crimping is very good from a joint fatigue point of view, we used to do that on aircraft wiring...all wires terminated with a crimp, no solder as it forms a brittle joint that will fail when subject to vibration or movement plus its a hell of a lot faster to crimp than solder with no risk of a dry joint.

 

[cwah]

NRJ can you point me to any tool and terminal that would allow to crimp 20-24AWG wires? These little wires are annoying to solder and never managed to crimp them properly.

 

[NRG]

WC-240 - JST (JAPAN SOLDERLESS TERMINALS) - CRIMP TOOL | Farnell United Kingdom

 

[NRG]

....or more affordable but probably of dubious quality:

Pololu Crimping Tool: 0.1-1.0 mm² Capacity, 16-28 AWG (POL1928) | Proto-PIC.co.uk

http://www.ebay.co.uk/sch/i.html?_nkw=jst+crimp+tool

 

[cwah]

267£ for a crimping tool?? that is damn expensive lol.

Also, what terminal can be used with this tool? I noticed the common plug we use for ebike are really unreliable:

I can't count the number of time one or many wires pull off the plug from vibrations or other. And also the number of time some wires snapped out from too high pulling strength

 

[shemozzle999]

Or this one for use on our JST 2.5mm connectors:

1 x Crimping Tool for Hobby 2.0 PH , 2.5 XH , JST , Servo Connector Plug | eBay

 

[NRG]

The thing is though if there's any tension on the wires or they get snagged they will fail at some point no matter how they are terminated. Eliminate that and the failure rate will drop.

 

[cwah]

The thing is though if there's any tension on the wires or they get snagged they will fail at some point no matter how they are terminated. Eliminate that and the failure rate will drop.

I can't because my brompton is made to be folded. Wires move a lot during this folding process. I see it like the braking cables from the bike, they move a lot but stay in place!

That's what I want to do with my wires.


Also, now I'm trying the DB connectors:

It needs soldering but wires are protected inside a plastic case and allow me to harness all the wires at once!

 

[NRG]

Good idea, one connector instead of many and with strain relief...