Choose rechargeable lithium-ion for any light you use every week: running costs fall to almost nothing, and many lights only reach their full published output on their rechargeable cell. Choose CR123A primaries for a light that sits unused for months or works in deep cold: SureFire quotes a 10-year shelf life, and Energizer rates its 123 cell down to -40 °C. For most British shooters, a multi-fuel light that takes both is the best answer.
The economics are easy to show. Say a two-cell weapon light gets fresh CR123As every six weeks during a busy training year. That is around nine changes, or 17 to 18 cells a year, and it doubles if you change them monthly. Over a few years the primaries can cost a real fraction of the light. A rechargeable equivalent costs you one cell, or none if the pack is built in. But cost is only half the argument; the other half is chemistry.
Key takeaways
- CR123A is a 3.0 V lithium manganese dioxide primary; SureFire quotes a 10-year shelf life for its 123A cells.
- Cold favours primaries: Streamlight rates the TLR-1 HP-X from -20 °C on its SL-B9 pack but from -40 °C on CR123A.
- Rechargeable cells often unlock higher output: the SureFire M340DFT publishes 650 lumens on its SF18350 but 350 on a CR123A.
- Only use rechargeable cells in a light whose maker approves them; lithium-ion runs at a higher voltage than a 3.0 V primary.
- Multi-fuel lights let you train on the rechargeable cell and carry primaries as the cold-weather and emergency reserve.
What CR123A primaries do well
The CR123A is a lithium manganese dioxide primary cell, nominally 3.0 V and around 1,500 mAh, according to Energizer's datasheet (Energizer 123). Its main strength is storage. SureFire quotes a 10-year shelf life for its 123A cells (SureFire 123A). That is why the format became the default for lights that must work after months untouched, such as one left on a rifle in the cabinet or an emergency torch in the car.
The second strength is cold, and in Britain that's not academic. Energizer rates its 123 from -40 °C to 60 °C. Streamlight's own figures for the multi-fuel TLR-1 HP-X show the gap: -20 °C (-4 °F) is the lower limit on its SL-B9 rechargeable pack, against -40 °C (-40 °F) on CR123A (Streamlight TLR-1 HP-X). On a January foreshore or a Highland hill, that margin matters.
Third, swap speed. A flat primary comes out and a fresh one goes in within seconds, in the dark, with cold hands. No cable, no power bank, no waiting.
What rechargeable systems do well
Rechargeable lights come in two types. Some take removable lithium-ion cells: 18650s, the shorter 18350s and 16340s, or proprietary packs. Others build the cell in and charge over USB-C. The major makers have fully adopted both.
- Streamlight uses its SL-B9 pack in the multi-fuel X, HL-X and HP-X weapon lights, which also accept a CR123A. Its larger SL-B50 pack (3.6 V, 4,900 mAh, rated for at least 500 charges) powers the ProTac 2.0 series, including the ProTac 2.0 Rail Mount (Streamlight SL-B50).
- SureFire makes dual-fuel Scout Lights: the M640DFT runs on an SF18650 or two CR123As, and the M340DFT on an SF18350 or one CR123A.
- Holosun's P.ID lights run on rechargeable cells. The P.ID-K uses a 16340 that Holosun says can be swapped for a CR123A (Holosun P.ID-K).
The advantages add up quickly:
- Running cost collapses. Heavy users stop thinking about battery cost.
- Higher output. Many dual-fuel lights publish higher figures on their rechargeable cell. The SureFire M340DFT gives 650 lumens and 95,000 cd on its SF18350 against 350 lumens and 55,000 cd on a CR123A (SureFire M340DFT). The Streamlight TLR-7 X gives 725 lumens against 550 (Streamlight TLR-7 X).
- Top-up habit. You charge the light the way you charge your phone, and you start every session full rather than guessing how much is left in part-used primaries.
The weaknesses mirror the strengths. Lithium-ion loses charge in storage faster than a lithium primary, so a rechargeable light left for months should be checked and topped up before you rely on it. Cold trims its output and capacity. And when a built-in pack goes flat in the field, you're done unless you carry a power bank.
The comparison in one table
| Factor | CR123A primaries | Rechargeable lithium-ion |
|---|---|---|
| Storage | 10-year shelf life quoted by SureFire | Check and top up before relying on a stored light |
| Cold | Rated to -40 °C (Energizer) | Output and capacity fall; SL-B9 rated to -20 °C in the TLR-1 HP-X |
| Running cost with regular use | Adds up quickly | Near zero after the first cell |
| Field replenishment | Swap from pocket spares in seconds | Swap only if cells are removable; otherwise recharge |
| Peak output | Often lower on dual-fuel lights | Usually unlocks the published maximum |
| Best suited to | Stored lights, deep cold, long remote sessions | Lights used weekly, training, everyday torches |
Voltages, protected cells and the details that bite
Voltage. A CR123A is nominally 3.0 V; lithium-ion cells run higher (Streamlight's SL-B50, for example, is 3.6 V). Rechargeable "RCR123" or 16340 cells are the same size as a CR123A but not the same electrically. Use them only where the light's manufacturer says you may. SureFire's guidance is that the only rechargeable cells to use in its LED lights designed for 123A primaries are its own LFP 123A rechargeables (SureFire battery safety).
Protected cells. If you buy removable 18650s, protected cells carry a small circuit against over-discharge and short circuit, at the cost of a little extra length, and some lights will not close over one. Check what the manufacturer specifies and buy from a proper source. SureFire warns that counterfeit and inferior lithium cells have caused fires.
Replace cells together. In a two-cell light, never pair a fresh cell with a part-used one or mix chemistries. SureFire's instruction is to replace all batteries at the same time.
UK note
British night work often means long hours in cold, wet weather, far from a socket: wildfowling on the foreshore, foxing, hill work. That is the one situation where the old CR123A arguments still win outright. A multi-fuel light run on its rechargeable cell for training, with a set of primaries in the bag for winter nights, covers both. For the rules around lamping and night shooting, see optics for fox and night vermin control.
Matching the power source to the role
A light that lives on a stored rifle or in the car should run primaries. Its whole job is to work after months of neglect, and shelf life beats every other consideration.
A training or competition light should be rechargeable or multi-fuel. High usage is where primaries cost most, and the higher output is a bonus. Browse rechargeable weapon lights.
An everyday torch is the easiest call: rechargeable, ideally USB-C. Our handheld torch buying guide covers size classes and switches.
A wildfowling or hill light leans back towards primaries, or a multi-fuel light with primaries as spares.
For picks across both formats, see best weapon lights. If battery life on an optic rather than a light is the worry, shake awake and solar failsafe explained covers that side.
Frequently asked questions
Is it safe to charge a light overnight?
Follow the manufacturer's instructions for that light. Built-in charging circuits manage the cell, and Streamlight's USB packs show red while charging and green when full. With loose cells, use a reputable charger made for that chemistry.
Can I use rechargeable RCR123 (16340) cells in a CR123A light?
Only if the manufacturer says so. They are the same size but run at a higher voltage than a 3.0 V primary. SureFire, for example, approves only its own LFP 123A rechargeables in its 123A LED lights.
How many spare CR123As should I carry for a night out?
Plan from the light's published runtime at the output you use, and treat it as generous. ANSI runtimes run until output falls to 10% of its starting value, well past the point where the beam stops being useful. One full spare set per light is the minimum.
Why does my multi-fuel light seem dimmer on CR123A?
Because it is. Many multi-fuel lights publish lower lumens and candela on a primary, because the primary cannot supply the same current as the rechargeable cell.
Shop this guide
- Rechargeable weapon lights: USB and multi-fuel models.
- Streamlight TLR-7 X USB: a compact multi-fuel light on SL-B9 or CR123A.
- SureFire weapon lights: including the DFT dual-fuel Scout Lights.
- Handheld torches: USB-rechargeable everyday lights.
