I am hoping to find the best battery monitor and I was hoping for recommendations as well as get a question answered:
To preserve the integrity of the batteries is it necessary to have a battery monitor that shuts down the power system before the batteries get below a certain percentage of power or is that accomplished by a separate part?
The answer depends on your individual system type and charging method. Many appliances have built in shit down settings some do not. Meaning when the battery voltage drops below say 10.5v the appliance will turn off. Check owners manual for each item to verify if it is equipped.
You do need to shut off all load on a battery when the voltage drips below 10.5 - 12 volts depending on what type of battery you have. There are many different type, flooded, lipo, etc. You would need to check the manufacturer if the battery to know what the exact voltage is but I have mine set up on 10.5v for my flooded batteries. I set each appliance separately and do not have a monitor for the battery. I have voltage meters all over that I monitor the voltage constantly, myself. I do this because I have a solar charge controller and want to know how it is charging.
A battery monitor is a very good idea especially one will some type of warning method. I do not know of any specific type to recomend because I do not use one.