Samsung Galaxy S21+ will not charge or charges slowly

The checks in more detail

In Settings, Battery and device care, Battery, Charging settings, make sure Fast charging is on, and note that Protect battery limits charge to 85 percent if you enabled it. Wireless charging is also available, and a pad that is not aligned or a case with a metal plate stops it. A phone that charges from some chargers and not others has a charger issue. Heat slows charging, so remove the case and avoid heavy use while charging. An aged battery charges slowly and runs hot, and Samsung can replace it.

Wipe the cache partition if charging slowed after an update. If the phone charges only when held at an angle, the port's contacts are worn or lint is packed in, and cleaning is the first step; a loose port that still wobbles after cleaning needs a repair, since forcing a charge through a bad port can overheat. Never use a bent or damaged cable. A final check is the wireless charging pad: if the pad is not Qi-certified or the phone sits off-center, charging stops and starts, and the phone shows a message about a problem charging.

Align the phone's center with the pad's coil and remove thick cases and card holders from the back, which block the coil and cause heat. If the phone is slow to charge at night, check Settings, Battery and device care, Battery, Charging settings for Adaptive charging or Protect battery, which pace the charge overnight on purpose to reduce wear, so an overnight charge reading eighty percent in the morning is intended. These features can be turned off if you prefer a full charge each time.