E-Bike Has No Power (KM5S)

In plain English

When nothing turns on at all, the cause is almost always somewhere between the battery and the display: an empty battery, a battery switch that's off, a battery that isn't clicked in, or an unplugged connector. Batteries can also put themselves to sleep after being fully drained or stored for a long time. Plugging in the charger often wakes them up.

Work from the top. Steps go from free and easy to shop jobs. Switch the bike off before touching any connector. Tick each step as you go. Your progress is saved on this device.

1. 1Charge the batteryFree Plug in the charger and leave it for at least an hour, even if the battery seems dead. A deeply drained battery can switch itself off to protect itself, and charging is usually what wakes it up.
2. 2Check the battery's own switch or keyFree Many batteries have a key or power button of their own that must be on. Make sure it's fully turned or pressed.
3. 3Hold the display power button longerFree Most displays need the power button held for 2 to 3 seconds. A quick tap does nothing.
4. 4Reseat the batteryFree Switch off and slide or lift the battery out of its mount. Wipe any dirt off the metal contacts on the battery and the mount, then put it back until it clicks and locks.
5. 5Unplug and check the main connectorsEasy Switch off and remove the battery. Find the round waterproof plugs along the cables (usually near the handlebar, down the frame and near the motor). Pull each one apart, look for bent pins, water, green corrosion or melted plastic, then push it back together fully with the arrows lined up.
6. 6Reconnect the display plugEasy Switch off. Follow the display's cable to its plug, usually near the handlebar or a little way down the frame. Pull it apart, check for bent pins or water, then push it back together fully with the arrows lined up. A half-connected plug is a very common cause of display errors.
7. 7Check for a fuse you can reach from outsideEasy Some bikes have a fuse holder on the outside that you can open without tools. Check your manual. If yours doesn't have one, skip this step. Fuses inside the battery are a shop job.
8. 8Measure the battery voltageModerate With the battery off the bike, use a multimeter on the discharge terminals and compare to its full-charge voltage: about 42V for a 36V battery, 54.6V for 48V, 58.8V for 52V. Make sure the battery's own switch is on first, because some batteries read 0V when off or out of the bike. Keep the probes from touching each other. Not comfortable doing this? Skip it and ask a shop.
9. 9Get the battery and controller testedShop job If the battery has voltage but the bike still won't power on, the controller or display may have failed. If the battery has no voltage after charging, a shop needs to test it.

Parts you might need

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Only buy a part if the free steps didn't fix it. Always match the voltage and connector type to your bike.

• Digital multimeter

  Checks whether wires are broken and measures voltage.

  Link coming soon

• Replacement e-bike charger

  Only if your charger is faulty. Must match your battery's voltage and plug type exactly.

  Link coming soon

• Electrical contact cleaner spray

  Cleans dirt and corrosion from connector pins and battery contacts.

  Link coming soon

• Replacement e-bike battery

  Only if a shop confirms your battery is worn out or faulty. Must match voltage, mount and connector.

  Link coming soon