Modlite flashlights are designed around a single Lithium Ion (Li-Ion) or IMR 18650 or 18350 cell depending on which body you purchase. CR123 lithium or RCR123 (16340) cells are not recommended and can actually overheat and explode if used in Modlite Flashlights.
Where Did The 18650/18350 Name Come From?
All lithium-ion batteries get their numeric identifiers from their size. In the case of an 18650 cell, (for instance) it’s 18mm in diameter and 65mm long. An 18350 cell means it’s 18mm in diameter and 35mm long. The zero at the end simply means it’s cylindrical. Some 18650 and 18350 cells will differ in length…but only slightly. The difference is with those that are “protected”.
Protected vs. Unprotected Batteries
Protected Lithium-Ion and IMR batteries (more about IMR batteries below) have a small electronic circuit integrated into the cell packaging. This circuit protects the battery against common dangers, such as overcharge, over discharge, short circuit/over current, and temperature. Protected batteries are safer to use in your light especially if the person using the cells does not understand the safe handling of Li-Ion/IMR cells. Protected batteries are less likely to ignite and cause personal or property damage due to the added protection circuit.
Modlite supplies protected cells in all the complete lights it sells. We feel that protected cells are generally the safest to use. This will get some push back from the battery geek squad but as a manufacturer we need to design to the lowest common denominator, so the extra safety of protected cells is what we offer and recommend. We do however sell unprotected cells and some of these cells offer a bit more current than protected cells due to the protection circuit limiter.
That said, with proper handling and storage of cells and with the use of quality chargers such as the Nitecore chargers we sell use of non-protected cells is very safe. So ultimately what cell you choose is up to you.
Here is what separates IMR cells from standard Li-Ion cells. IMR cells used in our 18350 batteries are a specialized Li-Mn (Lithium Manganese) chemistry specifically designed for high-drain applications. While they excel at delivering massive discharge rates, their capacity is much more limited than a Li-Ion of the same size. We use and recommend IMR cells in our 18350 bodies specifically because due to the size Li-Ion cells cannot deliver the current needed (8-10amps) to run the light head at full power. We are purposely not going into a lot of detail on cell chemistry here for the sake of brevity but if you want to know more check out the Battery University page on Lithium-ion batteries here.
What does mAh mean?
A 18650 or 18350 cell is a very powerful choice when it comes to operating a LED flashlight. Li-ion/IMR cell available power is measured in milliamp hours (mAh). The higher the mAh capacity, the better the capacity. Cells are marketed with capacities anywhere from 1200mAh in our 18350 cells all the way up to 3500mAh in our 18650 cells.
The after choosing a protected cell the two most important specs you want to look for in Lithium-ion cells to be used in your flashlight are capacity measured in mAh (milliamp hours) and maximum continuous discharge measured in A (amperes). Modlite recommends that only cells with at least a 8-10A rating are used it its flashlights. The exception is the Modlite PLH-Quad light head which a 15A cell or more is recommended.
Battery Brand Recommendations
Modlite recommends and sells the KeepPower brand of protected cells for all of it's flashlights. Other brands of protected cells will also function just make sure the cell is rated for at least 8-10amps of continuous draw. If you cannot find the specs for the battery that might be a clue to not use or buy the cell. In the case of the Modlite PLH-Quad light the minimum recommended cell needs to be able to deliver 15 amps of current. This is due to the extreme light output and current needs of this light head as it has four LEDs and the current draw is about 13.5-14A.