good link
some details about different types of “Lithium” cells
1. CR123 is a Lithium Primary (non rechargeable), with a nominal voltage of 3v
this is a disposable battery that was popular before rechargeables became available
there is still a large number of lights (Surefire), and people that use them… particularly in places like LEO and Military applications, where batteries are stockpiled and provided for free
2. LiFePO is a Lithium cell (rechargeable), also with a nominal voltage of 3v
this is a rare cell, used in security cameras that were originally designed for CR123, but whose owners seek a more cost effective, rechargeable option. They cant use 3.7v LiIon because the voltage is too high for those old circuits
3. LiIon is a Lithium Ion (rechargeable), with a nominal voltage of 3.7v
these are the “typical” cells in high output flashlights
multifuel lights
there are many CR123/16340 lights on the market
one example is the Jetbeam RRT-01
the lights work with both types of cells, but due to the difference in voltage, the maximum output is different between the two types.
the voltage difference makes it difficult to design a protection circuit inside the light, because the LiIon cell does not like to go below 2.5v (for recharge safety), whereas the CR123 does not care if voltage goes below 2.5v, since the cell is disposable.
these dual fuel lights usually recommend using only Protected LiIon… because the driver cannot distinguish.
there is one dual fuel on the market that has a sophisticated enough set of options, that it can use UnProtected LiIon and also CR123. That is the HDS/Novatac design.
The Anduril lights only work on LiIon, they are not CR123 compatible. Anduril lights have built in LVP, that would get confused by a CR123 (the LVP would think the battery is discharged, when it is not)