The CH100 is a float-only charger that is limited to a 20 W solar panel and a maximum load of approximately 1 A.
The more advanced (and more expensive) CH200 is a multistage controller that can charge at higher rates and use larger solar panels (90 W) while delivering a maximum of approximately 4 A to the load, depending on the temperature. The CH200 is a smart charger that incorporates MPPT technology (maximum power point tracking) and can be interrogated by the data logger to check its state, solar panel status, load currents, battery voltage, and net battery current. In this regard, the CH200 acts as a high-tech sensor, as well as a charge regulator.
The CH100 has a temperature sensor for temperature compensation. The CH200 has a similar onboard temperature sensor, but it is more efficient and does not dissipate as much heat with a similar load. The CH200 also has a feature where an independent battery temperature measurement can be sent to the charger rather than using its onboard temperature sensor.