Diagnosis: bicycle battery charger does not work


Does your bicycle battery not want to charge orto fully? If so, the charger may be defective or malfunctioning. We distinguish the following possible causes:

1) Poor contact between the plug and the charging contact
This occurs when the charger’s tulip plug does not connect properly to the bike battery’s charging jack. The light on the charger stays green or jumps (at the slightest movement) from red back to green even before the battery is fully charged. The tulip plug is then often somewhat “stretched” so that contact with the battery’s charging contact is easily lost.
use pliers to deform the charger plug just so much that it clamps properly around the battery’s charging contact again.

2) The battery is charging but no longer in its entirety
It sometimes happens that the charger does charge, but not more than to, say, 60- or 70% of the maximum capacity.
A fully charged (36- or 37V battery) measures about 42 volts between the terminals. If the charger stops and the battery measures only 36 volts, for example, the charger may not be working properly. The best way to test this is to connect another charger after your own has stopped charging.

3) The charger is defective
If the LED light does not illuminate when the charger is connected to the mains supply, this may be a sign that the charger is faulty. However, even if this light does not turn red when the battery is (partially) empty, it may mean that the charger is faulty.
best to have the charger checked by an expert.

Battery charger is defective or malfunctioning

    1. The charger does not work at all
      The light on the charger does not light up when connected to the mains voltage AND the charger does not get hot when connected to the battery.
      The charger has probably failed and needs to be replaced
    2. The charger charges the battery, but not fully
      The light on the charger turns red and the charger gets hot, but the charging process stops before the bicycle battery is fully charged. The bike battery charge status shows that the battery is not fully charged.
      The charger is defective and needs to be replaced to restore 100% charging.
    3. The light does not turn red or only lights red briefly and then turns green again
      It may be a malfunction in the charger, but more likely it is the bicycle battery which is no longer charging.
      Check the battery first

In addition to the battery charger, the battery itself may be the cause of the problem.


here for possible bicycle battery problems.

If you have doubts about the condition and or operation of your battery you can also have it tested by RAP.


here for more information.