charge controller and diode
I used one like that for about 2-3 month when my MPPT charge controller croaked when I turned it it into a test. I hooked up a relay to it so it can handle more power.
It is not like an expensive charge controller, but more like an cheap controller.
You can use it as N.o or N.C contacts, You can set the upper voltage and lower voltage. You also can set the on time and /or the off time etc etc.
Well, let me just paste the operation modes
Operating modes:
P-1: Timer ( 1-999 S / 1-999 Min)
P-2: Delay timer ( 1-999 S / 1-999 Min)
P-3: Voltage control relay ( control the load on/off)
P-4: Voltage control Timer- A (close first)
P-5: Voltage control Timer- B (release first)
P-6: Voltage range control relay
P-7: Voltage range control Timer
P-8: Set display shut
I was satisfied when running the test and it keeped the batteries charged. I did not use it as dump controller, but as a controller to interrupt the power going to the battery. That relay must have turned on and off thousands of times to keep the voltage where I set it.
For an emergency it may be ok and using for such a small panel it may work also.