Which batteries in what? AW vs IMR???

[Brian321]

I am wondering if i can us IMR 16340 cells in all the lights that i can use AW RCR123's in? Or do specific aplications need specific batteries? If so how do i know what needs what? Thanks.

 

[mdocod]

Hello Brian321,

IMR16340s should not be considered direct replacements for protected RCR123s in all applications. Especially those that use buck or boost circuits that could severely over-discharge the IMR cells. (IMR cells have no protection to prevent over-discharge). While LiMn (IMR) chemistry is more robust and abuse tolerant than LiCo cells, that doesn't mean that they will last long if they are repeatedly over-charged or over-discharged.

Here's some general rules to follow on this matter:

If the flashlight has a built in protection that prevents over-discharge of a li-ion cell, then you can probably use IMR cells in place of protected RCR123s.

If the flashlight uses 2 or more protected RCR123s, and a buck circuit to drive an LED, IMRs should not be used as it will likely be able to discharge the cells to ~1.8V each or less before any dimming would be noticed.

If the flashlight uses a single protected RCR123 and contains a boost circuit that maintains output through the discharge, do not use IMR cells as the boost circuit will likely be capable of over-discharging the cells well below 2V. Many 1xCR123/RCR123 type flashlights use the same boost circuit as would be found in an AA/14500 counterpart. The boost circuits in many of these lights are capable of running right down to ~0.9V or less.

If the flashlight uses a single RCR123 cell but uses a buck regulator or runs in a direct drive configuration with an LED, then you can use IMR cells in place of protected RCR123 cells because this unit will dim down a noticeable amount before the cell has been severely over-discharged. Testing and experimentation would be required by the owner to determine how "dim" represents what state of charge.

If it is a non-regulated incandecent flashlight, you can use IMRs in place of RCR123s and this is actually my recomendation as most incans have power requirements that are really pushing the limits of LiCo cells in this size. When sudden dimming occurs the flashlight should be shut off and recharged to prevent over-discharge.

[edit in]: More specifically, IMR cells should be selected when the application will put a load on the cell that would push or exceed the safe limits of a protected RCR123 cell.

Eric

 

[Brian321]

Thank you for that info. What is the safe limit of the rcr123 cells?

 

[Black Rose]

Up to 2C is the safe limit on protected 16340/RCR123 cells.

Assuming an actual capacity of 600 mAh, that would equate to a 1.2A current draw.