The charger is generally a smallish black box, supplied with your trolley to charge up the
battery. The charger plugs into the
mains at one end with the other attaching to the battery terminals.
Most have a red light to show the battery is charging at full voltage output (bulk charge) with a
green light to show it’s dropped to a
low voltage output (float charge) and the battery is ready for use. Some
chargers may also have a yellow light to indicate nearly charged.
The most common fault with a charger is when the voltage
output malfunctions and causes the battery to prematurely deteriorate. This is
not easy to identify as the lights on the charger normally still function.