Electrical circuit interpretation
This a self-charging device, as the title of the link in the comments implies.


R1-D1 is a voltage reference using a Zener diode
R2-R5-RV2-D5 will cause the positive input voltage to drop if the output of U1 is low
R3-D2 and D3-R4 are status LED's
D4-R6-Q1 will switch the relay K1 on or off


If the battery voltage is too low, then U1 will switch its output high, causing Q1 to switch on. K1 closes the switch, allowing the battery to be charged again. During this time, D5 is off, and U1 works like a pure comparator. The battery will be charged until the negative input pin of U1 reaches the positive pin, which is at D1's Zener voltage.

When the battery is charged, the output will switch back low. This causes the positive input pin to drop in voltage as R2-R5-RV2-D5 conducts current. The relay switches off and the charging stops. The battery will discharge until the negative input pin drops to the level of the positive input pin, causing the cycle to repeat itself.