Problem with ground between two batteries and a battery level notificator
You are choosing a dual Op Amp comparator correctly but not choosing a differential input to bias -Vbat  as a a differential amp with positive bias to reach Vin &gt;=0 for common mode.  The voltage divider must be biased to +Vcc and not 0V for -Vbat to be compared.  then output on both LEDs is &gt;0V so you do not connect Anode to 0V but rather and comparator switches to 0V not -Vee.  This a common design flaw.