How to check your e-bike or e-scooter charger

CPSC says to use only the charger that came with your device or one the maker recommends, and warns against chargers sold as universal, because a charger can fit the port and still not be compatible (CPSC universal charger warning). If you lost yours, CPSC says to get a compatible replacement from the maker. UL Standards and Engagement adds that batteries and chargers should be certified to a recognized safety standard and approved by the maker for your device (ULSE safety tips).

With everything unplugged, look along both cables and at both plugs. Rad says to stop using the battery and charger and contact them if a cable is frayed or the insulation is broken, or if the charger has taken a hard hit from a fall, crash or shipping (Rad battery charging guide). Super73 lists exposed wiring, sparking or a smoke smell as signs a charger has failed (Super73 failed charger guide).

• Rad says to charge in a dry indoor spot away from children, sunlight and anything flammable, with the charger flat, its lights facing up, and nothing blocking an exit.
• Bosch says to charge in a dry, well ventilated area with a smoke detector, away from sunlight and heat (Bosch battery safety).
• Charging temperatures differ by maker. Rad recommends 41 to 77 F and says not to charge a battery that is warm from riding. Bosch gives 32 to 104 F. Use the range in your own manual.

Rad connects the charger to the battery, then plugs it into the wall, and unplugs from the wall first when done, pulling on the plugs, not the cables. Read the lights the way your maker documents them, for example:

-Rad, one light: green when plugged in, red while charging, green when full. Rad, two lights: both red while charging, one turns green when full.

• Super73: solid red while charging, solid green when full. On some models it can briefly go back to red to top off a battery left plugged in, which Super73 says is normal. A flashing red light means the charger has failed.
• Segway Max G2: red while charging, green when full (Segway Max G2 manual).
• Shimano: the charger light goes out when the battery is full, which Shimano says is not a fault (Shimano E-BIKE FAQ).

CPSC says to be present while charging and never charge while you sleep or are away from home (CPSC micromobility information center). Unplug once charging is finished. Super73 says not to leave its charger connected to the battery for more than 48 hours in a row.

Rad says a warm charger is normal, but one that is too hot to touch, smells odd or pops is not, and you should stop using it. ULSE lists a battery that is very hot to the touch, odd smells, smoke, hissing or popping as warning signs of a battery failing.