The LCD on the GPISEN is very bright and the producer did not include a way to turn the LCD off when it is not needed. Due to its features the charger is made to periodically deliver charge to batteries in order to keep them fully loaded such that keeping the batteries inside the charger is necessary.

The following modification is meant to provide a means of turning the backlit LCD display off with a switch.

On the bottom part of the GPISEN charger a few rubber feet mask screws that hold the charger together with the upper half. The rubber feet can be carefully removed using something sharp and then the screws removed to expose the screws.

Upon disassembly, the GPISEN splits in half and a few wires connect the LCD controller to the main charger board. Carefully, both halves are split to the side, exposing the circuitry and allowing access to the LCD controller board.

Looking at the datasheet, the CS1621 LCD controller backlight is controlled by a lead leading from the battery bays to the pin marked LED on the LCD controller.

A single throw switch is added that will allow the circuit to be broken between the LED pin and the battery bay board. When the switch is active, the LCD will be backlit. Toggling the switch will allow the backlight to be turned off whilst still allowing the device to work.

A file can be used to carve a notch on the case that will allow placing the switch on the upper part of the charger. Seating the switch, the two halves can be carefully brought together again and screwed in place.