The Definitive Guide to Electric Bike Connectors
The Definitive Guide to Electric Bike Connectors
For someone new to e-bikes, choosing the right electric bike connector for your e-bike battery can be a critical decision. If you become a true e-bike enthusiast later, the connector you choose now will affect your e-bike experience for the next 10 years. The reason is that you might choose to use the same connector on different battery packs so that you can use the same charger with different battery packs on different bikes. We recommend that you choose a good connector now and stick with your choice.
Inevitably, many DIY e-bike manufacturers use their connectors as on/off switches (read our story on on/off switches), in which case your connector will need to be more robust as it will Frequent mating and unplugging, which is difficult for connectors as they arc and spark.
When considering which connector to use, consider convenience, reliability, durability, waterproof rating, small size (how easy it is to hide), and price. The Ebike connectors for the battery pack wires should not accidentally be plugged in the wrong direction (this is called polarization)… keep in mind that if you use them for ON/OFF switches, you may end up in the dark Restless in the light.
For your convenience, the various ebike connectors are listed here with a quick summary of recommended maximum amperage and pros and cons.
I see these a lot as charging connectors on DIY bikes. That’s because chargers rarely charge more than 7 amps, and the connectors are cheap. They are an old technology that I feel has been surpassed by better connectors. Note that this is a mini version of the Anderson connector and should not be confused with its big brother, which is larger and I feel too big for an e-bike.
The shape of the 30A Anderson connector housing allows two (or more) of them to be connected side by side. It is “possible” to pair two of them so that they can be inserted backwards into the other pair. I recommend that if you buy these (or buy one with them already installed), connect the two shells side by side so that the pins inside form a “T” when you see the ends. Once they are configured to be secure, put a heat shrink tube over them to keep them from coming apart (and then possibly reconnecting in the wrong direction).
Their official name is Anderson Power Pole (APP).
Deans plugs are very popular with DIY electric bike builders and RC modelers. It has been found that they can handle a lot of amplifiers, are very cheap, and are small (their small size is the main reason for their popularity in wires inside RC aircraft fuselages). However, they are notoriously difficult to solder and have poor moisture resistance (it might not rain when you’re out, but it might start before you get home). If you’re buying these, we recommend getting the ones with pigtails (factory pre-soldered wire sections) that will make your life a lot easier. (Read our story on solderless electric bikes)
In the image below, you can see that even though the pair is fully connected, moisture entering the plug set can easily cause a short circuit. That’s what we call moisture resistance, and the Deans didn’t score highly.
As you can see in this photo, when the pair is disconnected, the male pins are completely exposed. This is why electrical tradition places the female connector on the battery side of any part of the system. If you’re working with parts on a workbench, male connectors can easily hit metal objects, causing short circuits, huge sparks, possible fires, and potentially damaging expensive batteries. Even if you use a double hood connector (like the XT below)…if you put the male end on the battery side, that’s one of the hallmarks of a hobbyist.
The XLR has a heavy duty metal housing with a latch that prevents them from accidentally separating. They are also very resistant to moisture. They can be ordered in a variety of pin counts, but the more pins you choose, the larger the connector will be. There’s nothing wrong with them, I like how the male prongs are wrapped apart, but…their bulk makes them fit snugly inside the battery case, and the metal case makes me nervous.
There shouldn’t be any loose wires inside the battery housing to short out the XLR connector housing, but…if there are any loose ones, I don’t want any metal exposed near many of the wiring connections. What’s better? Your e-bike stopped and you had to find a loose connector? Or…you suddenly smell smoke while riding?
These are our favorite electric bike connectors. They come in two sizes. We still recommend buying them with braids, but they’re easy to solder wires. If you’re soldering them, connect a male/female pair to keep the pins perfectly aligned until the end of soldering. The pins can be rotated in the housing (use needle nose pliers) if you want to lay them flat on their sides with the solder/wire “cups” facing up. I used these for 14ga/12ga wire and covered the solder joints with 5mm heat shrink. Ron likes to use these charging connectors for connecting the battery (the battery side is female!).
None of the connectors in this article are truly waterproof, but…XT connectors (and the connector types shown below) are as moisture-resistant as possible.
Same as the XT60, but slightly larger and doesn’t melt at 90 amps. These are expensive at 1.50 each, but worth every penny if you run high power. highly recommended. The wire insertion cups fit very thick 10ga wire (or smaller of course) and I used 6mm heat shrink to cover the solder joints. Hobby King’s “shrink” is very cheap. Ron uses these between the battery and the controller. Of course, your life will be easier if you order one with factory-installed braids.
Even though this type of connector housing has a well-designed “full wrap” shape on the male pins, it is still traditional practice to connect the female connector to the battery side of the wire. There may still be a small amount of energy stored in the capacitor when the controller is unplugged, but… the battery on a high current e-bike can melt hot if you put a metal tool on the table and the tip short the two male pins together.
The enclosed male plug on the XT90 connector makes this less likely, but… we still use the female connector on the battery side.
The pins within these plastic housings range in size from 2.5mm to 8mm in diameter and have corresponding current handling capabilities. The price/current deal ratio is the highest. The 4mm size is commonly used for RC chargers, but also for “HXT 4mm” plugs, which combine male and female bullet connectors with insulation within a polarized housing for a beautiful and easy-to-use connector. Moisture resistance is as good as our favorite XT90 connectors.
LiPo battery packs are the best choice for racing, but we want to encourage e-cyclists who charge their batteries at home to use safer battery packs based on 18650 cells. Having said that, the 4mm HXT connector shown is typically used to connect a 6S LiPo “sub-pack” (what we call a brick) to a wiring harness. This wiring harness (looks like an octopus) connects all the LiPo subpacks to a single connector that goes to the controller. The main connector should be much larger than the sub-package connector, we would recommend the XT90 (pictured above) to do the job.
Most battery packs have balancing wires that go into the battery management system (BMS). These small diameter wires allow the BMS to track the state of charge of each battery. Also, when battery packs are “batch charged” (a common method), the state of charge of each battery may vary slightly. Most BMSs will trickle discharge the taller cells within a few minutes, so the end result is a battery pack where each cell starts at the exact same exact voltage.
Balanced plugs are why we came to love factory pigtails (it just requires a simple “butt joint” to connect two wires). There was a project we wanted to look professional with as few wires as possible. We purchased pins and connectors for JST balanced plugs. These pins are tiny! , suitable for small wires. It’s a nightmare, and even if we think we’re doing well, a loose connection that “looks good” can destroy a battery in the middle of an expensive battery pack.
We mention JST balanced plugs because e-cyclists using LiPo battery packs have a parallel balanced plug harness so they can “balance charge” their battery packs (using RC chargers) as most DIY LiPo battery packs don’t use BMS
If you need JST balanced plug and socket kits, they are very cheap and factory made very well (don’t even try to buy and press the wires into the pins and then plug them in). Order an “extender” like the one pictured above, run a continuity check with a cheap voltmeter to make sure it’s good, then cut the wire in the middle.
QR code connector
QR stands for “Quick Release”. As with some newer smartphones, there is a connector called RoPD that is increasingly common on factory e-bikes. The shallow plastic housing is polarized so it cannot be inserted backwards, and the flat metal contacts are held together by magnets. I doubt DIYers will use these, but when you see them on expensive factory e-bikes, we think you want to know their names.
The latest technology is often the realm of commercial e-bikes, and these funky connectors shown below are slowly making their way into the DIY scene.
We really recommend that if you’re ordering connectors, buy them in bulk with pigtails installed (shipping usually costs more than connectors, so…why not buy extra?). This will make your life easier. Instead of welding yourself, let someone in China weld your pig tails for you. Then connect the 2 wires with a crimp and you’re done (bend the bare copper wires at both ends into a “J” shape, insert them into the copper cups, crimp them, and slide heat shrink over them). If you buy connectors from Hobby King, be sure to buy heat shrink tubing as well.
Instead of investing in a 100W soldering iron, invest in a good set of crimpers and some crimp connectors from Waytek. With these, you can perform electrical repairs even if there is no electricity around the soldering iron. We can use a simple cigarette lighter to clamp the heat shrink insulation on the wire splice.
Here’s our article on crimping and soldering wires to connectors. It’s written for intermediate drives, but it’s useful for any electric bike wiring work.
Source of e-bike connectors:
Powererx – A wide variety of connectors. A little pricey, but convenient and quick.
Hobby – Cheap source of connectors and adapters.. but you are ordering from China and shipping can be slow.
Excellent resource for Waytek’s various connectors, especially crimp connectors
Top Secret EV if you’re an e-bike maker and looking for a way to get your fancy QR connectors dirty
If you are looking for a new way of commuting or want a healthier lifestyle, we are here to help you. Visit our website to learn more about electric bikes and electric scooter or please leave information to us.