Solar chargers, wondering about the output connector

Some disconnect the load if the battery voltage runs too low, like at night.

Our chargers disconnect the consumption on low battery or overcurrent, and also measure the output current so they can show instantaneous

I looked at some available here, and given that they are not MPPT chargers, then what are in them?

I see that they have some voltage protection, and probably a diode for only charging the battery. Does something as simple as this contain anything else?

Essetially, I can do that with a diode myself

Those kinds of controllers are what they call PWM type. They usually have a power FET in them that is on full when the battery is being bulk charged and then they PWM the connection between PV input and battery output to regulate the average DC voltage at the Float and Absorb voltage. They usually have another FET to control a load like a light circuit.

Simplest types of controllers. The PV module must have its maximum power point voltage just above the highest battery voltage by usually a couple of volts... At 25 degrees C. MPPT charge controllers normally use a buck converter so the PV can be quite a bit higher in voltage than the battery which can be an advantage.

boB