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How To Troubleshoot Electric Bike Problems

Posted by EBC Support on

How do you troubleshoot an electric bike? Some people don't live near an electric bike service shop and or maybe you just want to try to fix it yourself. In this article, we'll go over some common ways to troubleshoot electric bike problems. 

Watch the video version of this guide:

Check the battery voltage

We get this question sometimes and the first thing we tell our customers to do is check the battery voltage. The LEDs should light up and the bike LCD computer should light up. Maybe the battery hasn't been charged or maybe there has been a blown fuse.

If you have a voltmeter, you can check the voltage of an electric bike by hooking up the prongs to the positive and negative sides of the prongs on the battery. You can also stick the voltmeter right into the charger connection on the battery to get a reading as well.

Usually if the battery loses power to quickly, your first instinct is to determine how long the battery pack has been left uncharged. If it has been uncharged for say, 6 months, you might be able to recharge the battery pack successfully. But, if it has been uncharged for more than 6 months, then it is most likely that your battery pack is defective. If you know that your electric bicycle has been sitting for a while without being recharged and your battery power dies out quickly, you can safely assume that the battery is defective and would need a replacement. If the battery has been charged for below 8 hours, try charging your battery for 8 hours and then see if the electric bike runs at full speed. It is a good practice to not leave the battery charger plugged into the electric bicycle for more than 12 hours because of the possibility of overcharging and also damaging the battery if the charger malfunctions.

You should also check the battery charger. There are no tools needed to do it. Just plug the battery charger into the wall and look for one or more indicator lights that are illuminated. If an indicator light is not illuminated or blinks on and off if the charger is plugged into the wall then the charger is defective. If you have a multimeter or voltmeter, you can test the output voltage of the battery chargers. The voltage has to be a few volts above the battery chargers rated voltage. If the output on the battery chargers is zero, or if it is below the battery chargers rated voltage then your battery charger is defective.

If you don't have a voltmeter yet, you can get one here:

If you have a 36V battery, for instance, and the voltmeter reads 7 volts, then you know the battery is faulty. At this point, you can check to see if your e-bike is still under warranty. If it is, you can contact the manufacturer to file a warranty claim for replacement parts. If it is not under warranty still, you can buy a new battery. If you bought your e-bike from us, you're in luck, we sell new batteries for every model e-bike we offer. Just contact us if you can't find it in the batteries section of our site which you can find in the menu above.

If you find that you have a surface charge of 42V from your 36V battery, then it is fully charged and you can move onto the next step.

Check the battery prongs

Sometimes, the prongs on the battery aren't lining up properly, so the electrical circuit can't be completed. This can be easily fixed using a wrench to bend them slightly and realign them. You also need to check the battery charger port. If the battery charger is plugged into the wall then unplug it. Plug the battery charger into the battery charger port on the electric bicycle and look for an illuminated indicator light on the battery charger. If the indicator light on the battery charger lights up when the charger is plugged into the electric bicycle, then the wiring and the wiring connectors going to the charger port are good and the charger port itself is good. If you have a multimeter, you can check the battery charger port’s voltage could be tested. The level of the voltage present at the charging port has to be the same as the battery pack. You could also test the battery pack on a known good electric bicycle and then riding the electric bicycle at full throttle on flat ground so you can see how long the battery pack would last. On flat ground, most electric bicycles would have a range of around 30-45 minutes. If the battery pack lasts less than 30 minutes, then the battery is most likely worn out and must be replaced. If the battery pack last less than 20 minutes then it is somewhat worn out and has to be replaced. Severely worn out batteries would only last 5-10 minutes.

If the electric bicycle has a headlight, a load test could be done by taping an arch-shaped piece of cardboard over the headlight so you could see the beam of the headlights shining on it if you are riding. You could then fully charge the battery pack and ride the electric bicycle with the headlight on, watching out for the headlights beam shining on the paper. If the battery is good, the headlight will only dim a little if you give the electric bicycle full throttle. If the battery is worn-out then the beam on the headlights will dim severely when the electric bicycle is given full throttle. If you have a multimeter and the electric bicycle is running, a battery pack load test could be performed by charging the battery fully. You should then jack up the rear wheel by connecting the a multimeter to the battery and give the electric bicycle full throttle while you engage but not locking up the brake on the rear. If you engage the rear brake, the battery pack is going to experience a load and you can then read the voltage to find out how much it drops. If the battery is good, the voltage will only drop by a few volts, however if the battery pack is worn-out the voltage is going to severely drop. 

Check the brake motor inhibitor (cutoff switch) wires

If you dropped your e-bike, most likely a part of the handlebars may have been damaged. This can easily be diagnosed if there is any cosmetic damage to your brake levers or handlebars. If the brakes happen to be pulled back because of damage and aren't being let free, then the motor inhibitor switch is always turned on. You'll need to fix your brake levers before you can get your e-bike working again. Sometimes the switch itself needs to be replaced. This would take the knowledge and expertise of an electric bike mechanic to do. Alternatively, you can locate your controller and figure out which wires are for the brake inhibitor and disconnect them completely to get rid of this issue, however, this can be dangerous while riding and we don't suggest it. 

If your brakes do not function properly, you should inspect the shoes or the brake pads for too much wear and replace them if they are damaged or worn out. You might also want to adjust the brake cable tension. If the brake pads or the brake shoes are in great condition then you might want to tighten the brake cable adjuster on the brake lever or on the brake itself until the brakes feel more responsive. Ensure that the brakes are not rubbing on the rotor or rim if the brake lever is released. If the brake cable adjusters have been adjusted to the end of their limits then screw them in all the way. Then, tighten the brake cable by loosening the brake cable stopper, pulling the brake cable tight and then tightening the brake cable stopper. The final brake cable tension adjustment could now be made by unthreading a brake cable adjuster until the proper tension is achieved. You need to maintain the braking system, keep discs and rims clean and straight. Replace the worn out brake shoes and pads promptly. Replace frayed or worn cables and housings. Lightly put lubricants on brake pivot points.

Check The Throttle

If you have an e-bike with a twist throttle, you may have the tendency to pull it back and let it go without a slow release. If you do this all the time, you can damage the throttle and eventually it will break. Proper use of a twist throttle is to pull it back and when you are done, don't just let it go, but put it back in its place slowly and softly.

If your throttle feels loose, then this may be the issue and you may need a new throttle for your e-bike. Thankfully, these are easy and inexpensive to replace. You can buy a new throttle at your local e-bike shop your contact the manufacturer to get a new throttle shipped directly to you. 

To test your throttle, you would need a multimeter, your throttle of course, your motor controller and a power source. First, you need to make sure that you have connected everything together. Power up the controller. If you have a controller with an on/off button make sure that the switch is in the ON position. Make sure that the multimeter has the black probe in the COM slot and the red probe in the VHz slot. Switch the multimeter to DC voltage mode and turn the dial to the 20V setting. The multimeter is now ready for use. Check that the throttle is being powered by putting probes in the back of the connector between the red wire V+ and the ground. You might have to push the probes in with a little bit of force so you can get contact. You have to see somewhere from 4V to 5V. With these tests, it does not matter which way round the probes go. The only difference is that you have a negative voltage if you are going to reverse them. If you have issues getting the probes to fit in the back of the housing, then you could try putting a small pin or nail in first and use the probe on that.

Next test the throttle signal by placing the probes between the black (ground) and the green (signal). Note that sometimes the signal could be a white wire. You should see a 1V the throttle is at rest. Then twist the throttle to full throttle.  You should see the voltage rise until it reaches around 4V. This means that the throttle is functioning correctly.

Check The Pedal Assist

If you having issues with your pedal assist mode on your e-bike, then this is something to check out. Every e-bike has a different pedal assist system, some are built into the bottom bracket while others are a ring of magnets built into the front sprocket chainring. If you have issues with the bike pulsating or the torque sensor being out of alignment, you will need to reconnect and readjust the sensor. The mechanical adjustments of the bike can often have an effect on a torque sensor if your e-bike has one, so keep this in mind when making adjustments to the wheels, sprockets, pedals, derailleurs and so forth. If you can't diagnose the issue, simply find the electric bike shop nearest to you and bring it in for a removal and replacement. 

If the pedal assist is a ring of magnets on the front sprocket, a common issue is the magnets got knocked around and are now too far from the sensor to work. In this case, you can use your hands or a flathead screwdriver to push the disc closer to the sensor on the bottom bracket. Sometimes the magnet disc gets knocked out of alignment and is wobbly, you can adjust this with simple tools and be on your way quickly and easily.

Check The Controller

Check your controller for any wires that are disconnected or not connected properly. If there is a disconnected wire, check to make sure it goes into the correct outlet by matching up the color of the wire with the color of the outlet, and reconnect it. If the wire isn't color coded, then you'll need to use trial and error to check which slot the wire should go into.

If the speed controller does not work, first thing you should check of course is the power switch. Make sure that it is turned on. You should check the fuse or circuit breaker. If the electric bike uses a fuse, check the inside of the fuse to see if it is burned out. The fuse may have to be removed from the scooter and held up to source of light to determine if it is burned out or not. For scooters that use a circuit-breaker, push-on or flip the circuit breaker to see if it will reset. Electric bicycles with single speed throttles will sometimes have to be pushed forward so that it may run. Pedal on the electric bicycle while you fully engage the throttle. As soon as the electric bicycle reaches walking speed and the throttle is engaged, the electric should run until the throttle is released or the brake is used.

Inspect by touch, smell and sight. Check if there are any burned or melted wires, electrical components or wire connectors. You should also look for disconnected, loose or damaged wires or wire connectors. Pull and push on all the individual wires and wire connectors and make sure that they are not loose or disconnected. Try to smell the controller. Any components that look melted or burned or that smell like burned plastic are almost always defective and must be replaced. Motors that small burned have to be replaced in order to prevent damage to the controller. Electric bike controllers are too complex to test easily. Testing the other components that are connected to the controller and using logic and the elimination process are the best ways to determine if the controller is working or not. If all of the other components that are connected to the controller test good then the controller has no problem.


Check The Rear Axle Motor Connection

If the wires that connect to the rear hub motor (if your e-bike has one) check that the connection isn't frayed or damaged in some way. If the wires are cut, then you'll need to re-wire your e-bike and an electric bike specialist shop will be able to help you with this.

Look for any burned or melted wires or wire connectors attached to the the rear hub motor. Burned or melted wires or wire connectors indicate overheating of the motor which could cause the plastic insulation to melt off the motor’s electromagnetic copper wire windings. Smell the motor for any burned plastic smells. If the motor smells burned, it indicates that its coils have been overheated. Motors with overheated coils should always be replaced to prevent damage to the controller. If the insulation melts off the copper windings they will short circuit and cause the motor to not run or run slowly. Short circuited windings could also burn-out the controller by giving it too much resistance which makes it work too hard and overheat.

You also need to inspect the power transmission system for missing parts and proper operation. Replace any missing, worn-out or damaged parts. Power transmission problems could be caused by a worn-out rear wheel freewheel clutch, a damaged or missing belt or chain or a missing or damaged belt cog or chain sprocket.

Check The Chainstay Motor Connection

To ensure the issue with your e-bike not working properly isn't simply a wire being disconnected, first check the motor connection on the chainstay, which is the part of the frame where you chain is. This is a simple connection that all rear-hub motor mount e-bikes share and is an easy fix if it is the issue. Also, make sure that the chain or belt is properly installed. Inspect the chain or belt to make sure that it is properly installed onto both the motor sprocket or cog and the rear wheel sprocket or cog. If the motor and chain or belt spin when the throttle is applied but the rear wheel does not move, the problem is a defective rear wheel freewheel clutch mechanism. If the motor spins when the throttle is applied but the chain or belt belt and rear wheel do not move, the problem is either a chain or belt that has fallen off, a belt which is not tensioned properly or a cog and sprocket that is missing or damaged. Chains and sprockets are going to eventually wear out and need to be replaced. It is difficult to determine how long a chain will last because it depends on the usage of the electric bike.

Get A Bike Stand To Help You Work On Your E-bike

One great tool to have for home repairs on your e-bike is a lift bike stand. E-bikes are notoriously heavy, so it can be quite difficult to properly work on an e-bike and not throw out your back or make your knees sore. Here's a great example of an e-bike lift you can get for your home garage:

If you are still having issues with your e-bike even after checking all of these systems, give your local bike shop a call and ask them if they work on electric bikes. More and more bike shops are transitioning to electric bike service due to their growing popularity.

I hope this article was helpful to you. If you found it useful, please share it on your favorite social network, forum, or group and if you have any questions leave a comment below.

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