Batteries

I agree that a battery monitor is a good investment, but I must confess that I haven't bought one yet.  I keep careful watch over my system manually, with a Digital Voltmeter.  I also use a data logger now and then.  I usually set it up to take battery voltage readings at 5 minute intervals.  After about a week, I download the information to my computer for display or printout. It is interesting to watch as the voltage begins to increase as the solar panels get morning sun, and watch it decline as the sun goes down in the evening.  I watch the effects of clouds, and of loads switching in and out.  Most importantly, I watch to make sure that my batteries are getting fully charged, and that they don't discharge too deeply.  It's easy to see when the charge controller switches to float mode.  I can also use it to monitor the voltage from my pv array, although that information is not as useful.  My data logger is not as accurate as the DVM.  You can find more information about the data logger I use at:  http://www.microdaq.com/lascar/usb/el-usb-3.php

John