Are you saying that kit ends up being cheaper, then, Chris? I don't think so, Mate. Now that I've looked into things a bit more, it seems that the whole "smart" battery story is very, er, smart. Great technology and all that, but I return to my earlier question of "what is the real benefit" in adopting it?
It's a fact that smart batteries are more expensive. Charging & discharging algorithm(s), charge/discharge/short-circuit protection, accurate State of Charge (SoC) indicator, accurate State of Health (SoH) indicator. To be smart the SBS forum states that a battery must be capable of SoC indication. You're forgetting single-wire and double-wire battery buses as well, Geoff. They're based on the same principles as SMBus though.
The problems with "smart" batteries are that newer battery technologies, that have overcome the issues with maintaining the battery itself (e.g. Li-Ion, Li-ion Polymer), have been replaced with issues associated with data corruption and calibration of the on-board SoC electronics and incompatibility with the chargers used with them (another reason for not buying non-recommended packs).
To some extent I think the use of SMBus and suchlike has allowed the development of batteries using technologies (Li, NiMH) that, potentially, have significant benefits over the traditional batteries we used in devices in the past, e.g. NiCd & LA- such as being totally maintenance-free.
Without the use of smart technology, i.e. the charging algorithms, protection, etc, then batteries using certain chemistry would most likely present a risk of over-heating or even exploding due to overcharging and short-circuiting because they tend to have a have a high energy-density and chemistry that can become unstable under certain conditions. It has been publicised.Unfortunately the maintenance-free requirement of the Li-Ion batteries, etc, has been spoiled by the fact that SoC needs calibrating periodically because of SoC "tracking" errors and the fact that the SMBus electronics can become "corrupted". Plus there's the compatibility issue relating to differences in how the SMBus is implemented in the charger and battery as Geoff implies.
