We have been selling poultry lighting controllers for the last eight years designed to increase egg production during the long nights of winter. See here for details: Poultry Lighting Controllers.
Pictured below is a modified version of our standard Mark 3 lighting controller (sold here: REUK Super Poultry Lighting Controller) to which we have added a low battery voltage warning LED.
This modified version is designed primarily for use in lighting set ups where a solar panel is not used, and so the battery has to be charged by the user. When the battery voltage powering the controller and connected lighting falls below 12.0V, the red LED turns on to show the user that they need to recharge the battery as soon as possible to ensure reliable operation and battery longevity.
Contact firstname.lastname@example.org if you need any kind of poultry lighting controller with details of your exact requirements.