Hello there,
If I read it right the cells are marked 3.0V rechargeable than they definitely are the protected type, because they use a little circuit to drop the voltage down and those have integral protection features IIRC. The big difference in rechargeables is they tend to have significantly less capacity in mah as opposed to disposable cells, which results in less runtime. The plus side is their different chemsitry allows for better current output under load in the form of less voltage sag than primary (disposable) cells do. This results in much more constant output during the whole range of the battery's discharge cycle (very little dimming), then rather abruptly dropping off (dimming fast) at the very end of their charge. So, shorter runtime but more constant (and higher) output for most of the run.
Disposables tend to run significantly longer but begin tapering off in voltage almost immediately causing reduced brightness (slow dimming) as they discharge while on for long periods. If the flashlight is regulated its not very noticeable but the as the voltage keeps steadily dropping the regulator sucks more current from the cell(s) to compensate so the batteries tend to get rather warm, even hot near the end of their lives.
The big plus with Lithium rechargeables is they have almost no self-discharge so they can be left in a light for long periods and still have all of their oomph intact when needed, plus they can always be thrown in a charger and topped off even after little use due to the complete lack of "memory effect" like Nicads. Even NiMHs require full discharges to keep them in top condition.
If you have lights you use a lot on an everyday basis rechargeables have a giant advantage over primaries, reducing operating costs to pennies an hour instead of several dollars, and no waste. Even as a seldom used light as a backup emergency light they work very well. The only way I'd use disposables for an emergency light is with fresh fully charged cells. In that application disposables have an advantage of longer runtime, which helps in a power outage or wilderniss setting where a battery charger isnt feasible or available. I've had lights sit for months in a drawer with rechargeable LiIons and measured full charge and got full runtime with them.
A downside of disposables is unless you measure the voltage with a multimeter or tester its hard to keep track of how much life may be left in them, whereas a rechargeable can just be thrown in a charger for a top off anytime, assuring full charge when its needed.
Also, the 3.0V 123 batteries you have are safe to use as direct replacements in any CR123 light, but most rechargeable 123s have a higher voltage which can damage some lights converter electronics. They are 3.7V instead of 3.0V, and are up to 4.2V right off the charger. There are a ton of threads on CPF about rechargeable compatability with individual lights, so just do a search for the light in question.
Hope this Helps
