90% of my ebike issue come from the wires

[alemanyorks]

Interesting thread, I've just put together a kit & was worried about the quality of some of the connectors that came with it (bullets & ones in cwah's pic) but they seem pretty standard. I was considering changing for soldered types but maybe not after reading this, think I might get a good crimp tool.
I did use as much glue lined heat shrink as I could though, really useful stuff.

 

[Deleted member 4366]

Crimping is OK (probably better) for the thin wires, but battery, controller and motor power wires need decent soldered connectors.

 

[cwah]

D8veh, why crimping is better for thin wire? In my experience thin wires tend to snap with crimping.

Bigger wire work better (for me) when crimping because you have a better crimping area

 

[mike killay]

Is there any reason to use these very thin wires?
Why not use thicker ones?

 

[cwah]

For space and clutter. Something like the throttle or hall wires don't need to be big.

 

[morphix]

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?

My e-bike (self-build) has only ever failed on me on two occasions...and on both occasions it was a wire connection just coming loose from one of the sensors on the motor.. I have a little LCD panel for the controller and it flashed up a spanner symbol and ERR code indicating motor failure That's quite handy as it enables you to locate the source of the problem much quicker if you can remember the error codes.

 

[Old_Dave]

Crimping has been used as the default method in automotive and other electrical products for quite a while now

The tips for success are to use the correct sized crimps for the multi strand cable and to use a proper crimping tool (not the kind that's a combined tool that serves as pliers / wire strippers / wire gauge sizes and is of Christmas cracker quality)

As d8veh says ..

battery, controller and motor power wires need decent soldered connectors.

And I'd kinda agree

 

[Deleted member 4366]

D8veh, why crimping is better for thin wire? In my experience thin wires tend to snap with crimping.

Bigger wire work better (for me) when crimping because you have a better crimping area

When you solder thin wires, the solder is hard and has no resistance against frequent bending, so any regular movement in the wire and the solder breaks. This isn't a problem with thicker wires because they're stronger, but instead, they're thicker because they need to carry heavier currents, wher contact resistance is more important. When they're soldered, you have direct conductivity to every strand, but when crimped, only some of the ones on the outside, and even then, it's only surface contact, so can waste energy when big currents flow and get hot.

The contact resistance is not such a problem for small wires because they don't carry enough current.

You can improve the stength of thin soldered wires by not letting them wiggle. i.e tied or glued down, but, as Morphix found, if they're left hanging in mid air, it's only a matter of time before they let go.

 

[morphix]

You can improve the stength of thin soldered wires by not letting them wiggle. i.e tied or glued down, but, as Morphix found, if they're left hanging in mid air, it's only a matter of time before they let go.

Yes on my kit the connection from the motor has these big heavy duty "pins" that go into sockets well insulated..but you have to really push them home snug. I think because my kit is on the handlebar on my bike and tends to move around a bit when I go over bumps and rough roads..it made the pin come out which wasn't seated in all the way.

If you're making your own cables and connectors the soldering is obviously the weak point..and you have to do a good job. I did mine and tested it thoroughly and then I use some good strong heatshrink over it to reinforce the connector and socket leads. I've noticed the Chinese go further and do some eproxy glue/rubber stuff all over the solder joints but I don't like that..maybe that's more for insulation rather than strengthening.

 

[cwah]

Thanks guys.

I've always soldered thin wires with lot of solder + glue lined heat shrink with thin wires... but they tend to snap.

Actually they snap at anypoint. I've been thinking about protecting them with a bigger heatshrink covering everything.

What connectors do you use for crimping? The one used on the ebike are crimped and then soldered after to strenghten the connection. Not just crimping.

 

[Scimitar]

Soldered connections on vehicles are a crap item. Crimp, using the *right* connector and the *right* tool and nothing will go wrong.
The current-carrying capacity of a crimped joint is in no way inferior if it's done correctly. What can cause trouble is when the joint is allowed to fill with road crap and moisture and them corrode invisibly.
Think of this - every time you're in an aircraft, your safety depends on thousands of crimped electrical joints - they're done right, with the right tools and everyone's happy.