Diagnosis: bicycle battery charger does not work

IS MY BATTERY CHARGER DEFECTIVE?

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.