Electric Bike Parts, What Fits My Older Electric Bike?

Electric Bike Parts, what fits my older electric bike? What can I modify to fit my bike?

A brief overview of what electric bike parts do, and how generic electric bike parts can be adapted to your bike.


electric bike parts - plugs, wires, & connectors

Hardly a day goes by without a call that goes about like this; "I have a (whatever) electric bike that I used to ride 6 years ago. Now I need a new battery, or some other part". Too often the vendor it was bought from is long gone, and often enough, the entire brand is history. Or it can be a conversion kit with no particular brand. The vendor was just some E bay guy who's not able to supply parts, has no idea what he sold, etc. Here at E-BIkeKit, we do sell parts for our kits, but they don't plug and play with other brands. If nothing else, our plugs are not the same.  And speaking of plugs, 90% of the time, if an electric bike won't go, it's simply that a plug is loose or broken. Check all the wire and plugs before jumping to the conclusion you have a broken motor. So what can be done if you need electric bike parts for an older e-bike? First, let's just look at what these electric bike parts are, and what they do.

The wiring and plugs are like your nervous system, one problem here, and any part of the bike can refuse to function. One common fault is that a crash or the bike falling over damages the wire leading out of the motor. The other common problem is a bent pin in a plug causing a plug to be unable to fully plug in, or it pushes a contact back out of the housing.


electric bike parts - the motors

Nearly all current electric bikes use a brushless DC motor. Older versions like the Ford Think, or the EV global used brushed motors. If there are only two wires leading to the motor, it's definitely a brushed motor. One nice thing about the old brushed motors is they are easy to test. Just connect 12v DC from a battery to the motor directly. A good motor will spin, a bad one will just sit, or run poorly, making a sputtering noise as the brushes arc. Brushless motors are much harder to test, but there are brushless motor testers on E-bay, for less than 25 dollars.


electric bike parts - the controller

The controller is a bit like the electronic ignition computer in your car. Its role is to convert raw DC from the battery into a variable signal that makes the motor run. For brushless motors, there are usually 8 wires to the motor. Three fat wires, and five thin. The five thin wires tell the computer what is going on with the motor. That information then gets used to send timed pulses of power down the three big wires. Each wire gets a pulse just in time for when a magnet is passing that coil in the motor. So the 123, 123 timing makes the magnet keep wanting to move over to the next coil. The controller also limits the power given to the motor. This way, the motor is able to run at a power level that will not harm the battery, match a legal power limit, or just limit power for better economy. The same brushless motor tester can test brushless controllers. 


electric bike parts - the display

Older e-bikes often have a primitive display. Usually this is a simple battery meter of some kind, which may also function as a powered up indicator. It may be very primitive, such as three LEDs on the throttle. Newer e-bikes have sophisticated displays that include speed, odometer, on off switch, trouble icons, power level switch, battery level meter, and power in use meter.


electric bike parts - the throttles

The throttle takes a 5v signal from the controller, and sends it back as anything from 0v to 5v. 5v signal back is full speed. The throttle uses three wires, but some throttles also include switches, or a primitive battery display, and will have extra wires for those functions.


electric bike parts - the e-brakes

The e-brakes are a safety that cuts off the throttle or the PAS when the brake handles are pulled.  Needed on a pas only bike, but if your bike has throttle only, they are a bit redundant. Either type, the bike can run fine without them.


electric bike parts - canvas battery bag to hold the battery

The battery is like the gas tank, it holds the electrons until opening the throttle tells the controller to release them to the motor. But unlike gas, batteries are a specific voltage. In general, your battery needs to be the same voltage as the original battery was.

So now lets assume your manufacturer or vendor no longer exists, or just doesn't stock the electric bike parts from last decade. What can you do? What electric bike parts are interchangeable? What modifications are needed to use generic electric bike parts on your bike?


Replacing or fixing the plugs and the wires – As I said before, usually the problem is in the plugs and wires anyway. If the bike just won't start, but it's not the battery or battery plug, the first thing to try is unplugging the e-brakes. Next look at the plug to the throttle. Often the first clue that the problem is the wiring is a motor that judders, or stutters. It may just jerk slightly when you open the throttle or it may run, but very jerkily while making horrible noises. This is nearly always a bad contact on the wires to the motor. But the problem is usually very hard to see. You will have to look very closely to spot a bent pin in a plug, and sometimes a cut in a wire can happen in the darnedest places, where you'd never think to look. Look first for damaged wires at the axle of the motor, then follow the wire all the way to the controller. If your bike has the type of plug with a removable pin, look very closely at the plug to be sure the contacts are fully inserted. Look both when unplugged, and again after you connect the plug. Look to see that the wire is not frayed where it connects to the pin. The more modern molded waterproof plugs avoid this problem, but they still can get a bent pin. Bent pins happen when you try to connect with the plug misaligned, so pay close attention to plug key ways, and alignment arrows on plug housings.  

If you know a plug is broken, and it appears to be unrepairable, then it can be quite a hunt for an exact replacement. Not knowing what the type of plug is called can be half the problem. Google needs a word to search. It can be easiest to just change to a different type of plug that is easy for you to find and install. One such type is known as a "scooter plug". These plugs with the square white housings are easy to find at electric scooter parts retailers.  In the older bikes, most used that type of plug to begin with. The scooter plug is also easy to work with. If you replace a motor or controller with a generic one, you might need to put a new plug on both your motor and your controller, to get matching plugs on both.  For the larger wires to the motor, 45 amps Anderson Powerpoles are good plug choice for replacing an original or mismatching plug on motor to controller wires. Then the six pin scooter plug works ok for the 5 small motor wires. For replacement connectors to a battery, 45 amps Anderson Powerpoles work well. Don't get tempted to use old extension cord plugs. They can be plugged in backwards, which will blow your controller.

As a last resort, you can cut plugs off and then make permanent connections. Solder the connection then use shrink tube to insulate the connection. For a temporary fix, you can even use wire nuts.  When I tour on an e bike, I carry some extra wire, tape, and wire nuts for an emergency fix.

Replacing the Motor – Fortunately a good brushless motor is very hard to break, so replacing motors is actually a bit rare. It's worth it to buy the tester, and be sure your motor is toast before you jump to conclusions. Brushed motors overheat more often, but the fix could be just new brushes. It's easy to test the brushed motor without special tools. If you have an antiquated brushed hub motor, consider a complete re do. Upgrade your bike with a new conversion kit. It's worth it, since the brushless motor is more efficient, and longer lasting. If you have an old brushed mid drive bike like the Ford Think, it might be well worth while to convert it to a hub motor.

If your bike has a brushless hub motor, then you can find a similar motor at on line stores, such as where conversion kits are sold, or direct from China. Replacing just the motor does get tricky though, because the order of the wires to the motor are unlikely to remain the same. The convention is this, three big wires, that are blue green and yellow. Then 5 small wires, one red, one black, the rest are B G Y.   Only the smaller black and red wires are guaranteed to connect the same. Because the motor may be wired inside differently, you may have to connect the green wire to blue, or some other variation. Trying each possible combination one by one will eventually result in the motor working in forward direction. You will also find a good backwards combination. This problem can be avoided by replacing both the motor and the controller with a matched set. That becomes almost the same as just starting over with complete kit. And, you are sure to have some incompatible plugs to sort out if you just replace the motor.

Replacing the Controller – The more modern controllers come matched with a display that turns the bike on and off, selects power levels etc. If you cannot find an OEM controller for this type bike, you will have to replace the display too, buying a controller and display that are a matched set.

Brushed motor controllers are generally less reliable than the brushless type. So needing a new brushed controller is quite common. Replacing a brushed controller is pretty easy, since there is only two wires to the motor. If the motor runs backwards, swap wires to make it go forwards. There may be the typical plug incompatibility with the other plugs, like to throttle and key switch etc. But usually it's quite easy to find generic controllers of the same voltage and wattage as your old one. ebay, or scooter parts web stores have them. Sometimes, original used or even new parts can be found on ebay, but not every day.

Brushless controllers can also be replaced with generic controllers from any source. This includes controllers intended for scooters. ebay generally has the lowest prices. Just match the voltage and wattage. But with brushless, you are back to the same problem with the order of the blue green and yellow wires to the motor.  Happily, there are some easy solutions. If your motor is the direct drive type, it can run without the 5 small wires that go to the hall sensors in the motor. This works with a sensor less type controller. The sensor less controller still has the three big wires, but finding the right combination to run the motor is very easy with just 3 wires to try different combinations. If you have a planetary geared type motor, then you must run it with sensors. One beautiful thing about the latest generation of replacement controllers is that many have a feature called self-study, or self-learning. What this does, is the controller will figure out what combination to use to run forward. Just hook up your motor wires with all colors matched up. There will be two matching one wire plugs on the controller, when this wire is connected in a loop back to the controller, the motor will begin to turn forwards. It's now set to work properly, without all the trial and error. Unplug the jumper, and it will be ready to ride. Look for self-study when you buy a new controller. It's a great feature!

Replacing the Display – If your display is simple, having only a battery meter, it can be swapped out with a similar battery meter, or even an LED voltmeter, to display battery level in volts. It's pretty simple, once you determine which wire to the display is the positive one. With a voltmeter, look for the wire that has full battery voltage on it. If you have a more modern full function display, and you cannot find an OEM replacement, you may have to replace the controller and the display as a set. Your original controller will not work without the correct display.

Replacing the Throttle – The throttle uses three wires. One is 5v from the controller, usually red. One is neutral back to controller, usually black. One is the 5v signal back to the controller, the signal that actually adjusts the speed of the motor. Often this wire is white. 4 wire throttles are also common. On these, a blue or purple wire goes to a simple battery display. You can omit that full pack voltage wire, if using a three wire throttle as replacement. Some throttles will have other switches on them, such as a three speed switch. If so, you should still be able to locate a generic throttle with the three speed switch. Other switches like lights or horn can be replaced with any type of generic switch.

Replacing the PAS – This is much like replacing a throttle. Generic replacements will work fine, once you sort out any plug incompatibility.

Replacing the E-Brakes – Like the throttle or PAS, the only real problem with using a generic e brake is getting the plugs to match. The circuit is simple, since the e brake is just a switch that turns on when the brake handle is pulled. You can just omit e-brakes, since the off position of the switch turns the bike on.

Replacing the Battery – The first thing about the battery, is any replacement must be the same voltage, and nearly always a new lithium battery will need a new charger.  If your bike uses a lead battery, then you just find new 12v sealed lead acid cells that are identical in type to your old ones. Look for them where scooter parts are sold, e bike parts are sold, or where wheelchair batteries are sold.

Particularly on electric bikes that are not a conversion kit, replacing the lithium battery can be a major headache. It seems that battery housings change constantly in the industry. If your manufacturer no longer has a replacement, then a different battery will not fit your bikes battery slot. Nor does the plug fit. Sigh... it's been a rapidly evolving product, these e-bikes. Every time it looks like something will be a standard, it changes in 3 years or less. But the good news is that once you know your battery voltage, usually the bike doesn't care if the battery is different, as long as it's the same voltage it had before. Often the only solution to carrying the new battery is to use a rear rack rather than the built in slot on the original bike. To connect to the battery, find the wires to the original plug socket, and use more wire to extend the battery wire to new battery location. If the battery has no plug on it, and has only two wires, Anderson Powerpoles make a good replacement for the battery disconnect. One trick I have seen done, is to keep the original battery box on the bike. But now empty of batteries, it can have a wire added to connect to the new battery on the rack. It may be possible to keep functions like the key switch in place this way, and be the easiest way to connect the new battery to the-bikes built in battery plug.


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