Most battery manufacturers offer SM-Bus technology for data communication, which does create the impression that this is the right way to go. Look it up and SM Bus is in fact a simple 2 wire bus for low speed communication in a chip or on a small PCB, designed primarily for internal power parameter communication, which is fine.
The problems or unreliability start when communication is external and is exposed to noise – as so often in the medical environment. Data corruption leads to errors in charging and status reports. Batteries with erratic behavior suffering from “software bugs” are a good example. A well known one is the "False Full Charge" where the batteries believe they are fully charged, but are in fact near empty. This happens quite frequently in a battery operation, although the real cause mostly remains un-diagnosed.
Since the key Hospital complaint in regard to batteries is unreliability, one must consider that IT Carts run battery information through longer cables and in the case of the Circadian system which is more externally exposed, and uses smart battery intelligence and thus a higher level of bi-directional communication there is a need for optimum data integrity. Based on these considerations DCPower4C decided to opt for the much more robust CAN-Bus communication technology which is used in automotive and aerospace industries where reliable functionality is prized.