Battery-charging and charge-gauging ICs are very important parts of the power-supply subsystem. Without them, charging would be inefficient, overcharging would be a problem, battery lifetimes would be curtailed, and runtimes would be shortened. Thus, charging and monitoring the charge accurately, as well as the remaining energy in the battery, is a vital function, and many vendors offer ICs for this niche.
It's such a common and needed function that we even have a slang tem for these ICs: gas gauges. The problem is that this term is very misleading, since there is no “gas” involved at all, only electrons moving in and out of the battery, along with the resultant electrochemical changes. Yes, we all know that “gas” is also a colloquial term for “gasoline”, which is a liquid in any normal situation, but that's OK, since the public knows that in the context of cars, chain saws, and engines, “gas” is the shorthand for liquid “gasoline.”
But when it comes to batteries, there's lots of room for public misunderstanding. People who don't really know much about the topic but write about it anyway (mostly mainstream, quasi-technical journalists) tend to focus on, then highlight the potential fear factor. Calling it “gas”, with all the connotations and associations of something akin to natural or propane gas, is just not a smart move on our part. Yes, some batteries do vent, and some batteries overheat and can actually catch fire or explode; there's a lot of stored energy and high energy density in some of them. But that's a very different situation than a container of explosive or highly compressed gas.
Fortunately, I am seeing more care in the language and product literature among the leading battery-charger and monitor IC vendors. Some terms being used in place of gas gauge are fuel gauge, charge gauge, and charge monitoring, among others. Let's be careful what we call things, since our slang terms can sometimes mislead those who seek to scare and alarm without good cause.
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