Electric bicycle components such as throttles, motors and batteries usually come with some type of plastic electrical connector at the end of the wire. These connectors plug in to the ebike’s controller and make it easy to connect everything together.
In theory these connectors would also make it easy to remove a component and swap another in its place. However, due to the lack of standardization in electric bicycle connectors, odds are that any replacement part you get is going to have a different connector. When this happens, adding your new component can be frustrating.
But don’t fret! Today we’ll learn how to easily swap a connector onto any ebike component.
This tutorial assumes you have your old component with its connector, and you just want to swap the connector onto your new component so it will interface with your controller. If you are starting with a fresh, brand new connector then all you have to do is crimp on and/or solder your pins from scratch. But let’s assume we are actually moving our connector over from one component to another. In this example I’ll be using a throttle cable, but the process is identical for any component.
Note: before attempting any of the steps in this tutorial, it is imperative that you know which wires control which functions on the device you are swapping connectors. As you’ll see in the example photos below, the colors do not match up on my components so I had to ensure that I was connecting the correct wires to each other. When in doubt, consult any literature that came with your components. What’s that? 99% of ebike components come from China with no literature or instructions? Well, in that case, consult the electric bicycle forum Endless Sphere to make sure you’ve got your wires figured out. You can also check out my article on using the amazing resource that is Endless Sphere here.
Now that we’ve got that out of the way, here’s how you swap a connector:
Step 1: Cut off your old connector
Here you can see my new throttle wire on top. It comes with a white three pin connector, while my old throttle had a smaller black three pin connector, shown on bottom. The first thing to do do is cut off the old connector, as I’ve done with the black three pin connector, to prepare to swap it onto my new throttle wire.
Leave at least a couple inches of wire on your connector so you can easily solder it onto your new component’s wire. You’ll want enough room to slide heat shrink over the connection as well.
Step 2: Remove your new connector
Next, cut off your new throttle’s connector. You’ll probably want to save it in case you ever need it again. I have a box full of connectors for exactly this purpose. Whenever someone brings me a controller that needs repair or a new component they want to add, if the connectors don’t match up then I just dig through my box until I find the right one.
Step 3: Strip your wires
Strip your wires about 1/8″ to 1/4″ back from the end of the wires on both your throttle wires and the connector wires.
Step 4: Tin your wires
There are different schools of thought on how to accomplish this, but basically you need to coat the bare ends of the wires with solder. Generally speaking, you want to apply the tip of the soldering iron to the copper wire to begin to heat the wire. A few seconds later, apply solder to the wire directly (not to the soldering iron) until the bare end of the wire is coated with solder.
In actuality, cheap soldering irons and less than ideal conditions make this easier said than done. I’ll often take the shortcut and just simultaneous apply solder to the soldering iron tip and to the bare wire, even though this isn’t the standard soldering procedure.
It’s not really that crucial; the important part is that you just want to make sure you’ve got good solder penetration on the wire. It should look like the solder is actually being absorbed into the wire strands, not just coating the outside. If the solder seems to just bead on the outside of the wire, try bumping up the temperature on your soldering iron. You may have to hold the soldering iron onto a thicker wire longer to heat it sufficiently to absorb the solder. Even though solder melts at a relatively low temperature, the components and solder need to be about twice as hot as the melting point of the solder to actually soak in to the wire.
Step 5: Add heat shrink tubing
Heat shrink covers and isolates electrical connections from one another and is very important for ebike connections. Do not skip this step. If you don’t have heat shrink tubing, you can get away with wrapping the connection with electrical tape, but it’s better to use real heat shrink tubing.
Cut your heat shrink into sections about an inch in length and slide it over the wires on whichever side has longer individual wires. Make sure that the heat shrink is far enough away from the actual bare wire you will soldering as to not get heated by the soldering iron. I’ve prematurely closed way more heat shrink tubes than I can count in close-quarter soldering.
Step 6: Make your connections
Now that you’ve got your heat shrink tubes in place, you’re ready to start making your solder connections. If you did Step 4 correctly then you should already have a nice solder-infused tip on both wires.
To join the two wires, simply align one next to the other with the length of the bare wire overlapping (not aligned tip to tip) and apply the soldering iron to both wires simultaneously. The solder will melt and join the two wires together.
Leave the soldering iron in place for an additional second or two after the solder melts to ensure a good fusing of the two wires with wet solder, then remove the soldering iron. Allow the joint to cool before you move it so you don’t end up breaking the joint prematurely. This is where a Helping Hands device can really come in handy to hold your wires for you and leave your hands free for the soldering.
Step 7: Sealing the heat shrink
Once your connections are securely made, you’ll need to slide the heat shrink into place and seal it with a heat gun. Don’t try to use a hair dryer; you need an actual heat gun. If you don’t have one, you can pick up a very inexpensive, light duty heat gun which will be good for other projects like this in the future. It’s a tool that you’ll be glad to have. You don’t need an industrial quality heat gun, and having even a cheap heat gun around for sporadic use can be very helpful.
Some people use a lighter for this step. I’m a little bit ashamed to say that I have in fact used a lighter to seal heat shrink on more than one occasion. It does work, but it’s really not recommended and you have to be extremely careful not to destroy the heat shrink or your wire’s insulation. You’ll also never get as good or uniform of a seal as if you had used an actual heat gun. Save the lighter for emergency situations.
And that’s it!
After you’ve sealed your heat shrink then you’re essentially finished. Sometimes I’ll slide a larger piece of heat shrink over the entire outer wire to seal all the wires together and make the finished job look neater, but that’s just an optional step. You can also use spiral wire wrap to make the work look nicer as well, but again that’s strictly optional. As long as you’ve correctly matched up your wires, soldered them well and covered them with heat shrink then you’re ready to connect your device and get back on your ebike.
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