Electric Scooter and Bike Troubleshooting Repair Manual - Battery Charger Light Stays Green (2024)

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Troubleshooting Guide > Battery Charger Light Stays Green

Overview

When the battery charger's light stays green that can be caused by several things including a faulty charger port, faulty wiring or connectors or fuse between the charger port and controller, faulty battery pack wiring harness or connectors, blown battery pack wiring harness fuse, faulty battery pack, faulty battery charger output plug, or faulty battery charger. Electric scooters, bikes, go-karts, and other similar electric vehicles use a "smart" charger which automatically detects the battery or battery pack condition and for safety reasons will not recharge a battery or battery pack that is over-discharged, has an internal short circuit or open circuit, has an abnormal Voltage, has plate vulcanization, is wired in reverse polarity, or has other faults. Under any of these conditions the charger's light will stay green and not turn red and the charger will not charge the battery pack.

Check The Wall Outlet For AC Power

On some battery chargers the light will turn green when plugged onto the scooter and not plugged into the wall or not receiving power from the wall. Plug the charger into the wall outlet only and see if a light illuminates on the charger. If no light illuminates on the battery charger then test the wall outlet with another electrical appliance that is plugged in and working in a different wall outlet. If this appliance no longer works when plugged into the wall outlet that the battery charger was plugged into then the wall outlet is not energized with electricity and the circuit breaker which covers it may be tripped or faulty or the wall outlet itself may be faulty.

Check To See If The Charger's Light Turns Red When The Charger Is Plugged Into The Vehicle And Wall At The Same Time
After making sure that the wall outlet has power plug the charger into the vehicle first and the wall second. If the charger's light is red that indicates that the battery is charging. If the charger light stays green that indicates that the battery is fully charged, or that the charger port is not receiving Voltage from the battery pack, or that the battery is overdischarged and cannot be recharged.

Test The Battery or Battery Pack Voltage

(Tools Needed: Multimeter) Electric scooters, bikes, go karts and other similar vehicles use a "smart charger" and if the battery pack is over-discharged then the battery charger will detect this and will not recharge the battery pack for safety reasons. The battery Voltage that most chargers will not recharge at is 9 Volts per 12 Volt battery. Here are battery pack Voltages that the charger will not recharge if under: 18 Volt or less for a 24 Volt battery pack, 27 Volt or less for a 36 Volt battery pack, 36 Volt or less for a 48 Volt battery pack, 45 Volt or less for a 60 Volt battery pack.

Test The Battery Charger

(Tool Needed: Multimeter) After testing the charger port and confirming that it has Voltage then the battery charger can be tested. If the charger port has no Voltage then that issue will need to be fixed before testing the battery charger. To test the battery charger to confirm that it is recharging the battery or battery pack, first test the Voltage of the battery or battery pack to confirm that it is below a 100% state of charge and that it needs to be recharged. We have a Battery State of Charge Chart to help with determining if the battery or battery pack needs to be recharged. Once it has been determined that the battery or battery pack needs to be recharged, plug the battery charger into the vehicle's charger port, and then plug the battery charger into the wall. Next test the Voltage of the battery pack with a digital multimeter to see if its Voltage is slowly climbing. The multimeter should be set to a DC Voltage range that allows reading the tenths or hundreds of a Volt of the battery or battery pack. If the battery or battery pack's Voltage slowly climbs to a higher number then that indicates that the battery charger is recharging the battery or battery pack. Continue to charge the battery or battery pack until the light on the charger indicates that it is fully charged, then test the battery or battery pack Voltage to see if it is at a 100% state of charge as specified in our Battery State of Charge Chart. If the charger is not charging the battery or battery pack up to a 100% state of charge then the charger is faulty.

Test To See If The Polarity Of The Charger Port Terminals and Charger Plug Terminals Are The Same
Most battery charger plugs and charger ports have standard terminal polarity and will work together with each other. However sometimes an electric vehicle manufacturer will use non-standard plug or port wiring and a battery charger with standard plug wiring will not work with the vehicle, or vice verse. Sometimes when the terminal polarity is not the same the battery charger's internal fuse will blow or another internal component will fail and the battery charger will no longer have output Voltage. To test and see if the battery charger's output plug terminals and the charger port's terminals have the same polarity plug the battery charger into the charger port and then plug it into the wall. Then test the back side of the charger port to see if the terminal with red wire is positive and terminal with black wire is negative. If accessing the back of the charger port is difficult then the battery or battery pack's wiring harness main output wires can be disconnected from the battery or battery pack and the same test performed on those wires.

If the charger port has pins then wrap electrical tape or install heat shrink tubing around the sides of the metal probes leaving only the ends exposed and be careful not to touch the multimeter probes to both the terminal pins and side of a metal plug at the same time.

If the charger port has holes such as XLR charger ports do then it is best to not have anything covering the metal probes as covering them could interfere with making electrical contact with the terminals inside of the holes.