Pictured below is a 24V battery charging circuit which we recently made based around our more standard low voltage disconnects.
Rather than a low voltage disconnect, this is a low voltage connect with the output used to control a relay which in turn connects a battery charger to the 24V battery bank. For this particular unit, the charger will be a hydraulic turbine generator, but everything would work the same if a plug-in battery charger was being used.
When the voltage from battery bank is measured to be below a user set value continuously for 10 seconds, the output turns on which starts battery charging. Charging continues until the battery bank is measured to be above a second (higher) user set value continuously for 10 seconds.
If you need any kind of low voltage disconnect/connect or anything to monitor an charge 12V or 24V batteries, email firstname.lastname@example.org with details of your requirements.