CR2 vs CR17345: what differs, and which goes where
CR2 and CR17345 measure 15.6 x 27 mm against 17 x 34.5 mm. CR2 is a lithium cell at 3 V; CR17345 is a lithium cell at 3 V. CR17345 in a holder built for CR2: too wide, at 3 V against 3 V. CR2 in a holder built for CR17345: too narrow, at 3 V against 3 V.
Side by side
Every figure below is published by the maker for CR2 and CR17345; the last column is ours, the difference read off the printed tenths of a millimeter.
| Figure | CR2 | CR17345 | Difference |
|---|---|---|---|
| Diameter | 15.6 mm | 17 mm | +1.4 mm |
| Height | 27 mm | 34.5 mm | +7.5 mm |
| Nominal voltage | 3 V | 3 V | same |
| Chemistry | lithium | lithium | same |
| Capacity | 800 mAh | 1500 mAh | — |
| Stored energy | 2400 mWh | 4500 mWh | — |
| In the Energizer catalog | listed | listed | — |
| Sold as | CR2, DLCR2, KCR2 | CR17345, CR123A, 123A, DL123A, K123LA, 5018LC, 123 (EL123) | — |
Either way round
Fit and voltage are separate answers, and they change with direction: the holder is built for one cell, and the other has to live with it. CR2 is 27 mm deep and CR17345 is 34.5 mm. The diameter decides first: 15.6 mm against 17 mm is 1.4 mm apart, more than the 0.3 mm a holder forgives, so in neither direction does the question get as far as the voltage, even though both run at 3 V.
- CR17345 in a holder built for CR2 — CR17345 is 1.4 mm wider and will not enter; it runs 3 V against the 3 V the device expects, the same working voltage.
- CR2 in a holder built for CR17345 — CR2 is 1.4 mm narrower and sits loose; it runs 3 V against the 3 V the device expects, the same working voltage.
Drawn to scale
Both at one scale. The dashed line marks the height of CR17345: CR2 stops 7.5 mm short of it.
How long each one runs
CR2 holds 800 mAh at 3 V, about 2400 milliwatt-hours; CR17345 holds 1500 mAh, about 4500. In the same device CR17345 runs much longer, 1.9 times, which is the whole reason the bigger cell exists. Price follows less closely than energy does. Per cubic centimeter CR2 packs 462 milliwatt-hours against 643 for CR17345, so the difference is construction, not only size.
What each one is made for
Both are made for cameras, flashes and flashlights, which pull current in pulses, which is why they end up in the same drawer and get mixed up: CR2 at 3 V and CR17345 at 3 V. Read the code off the old cell before buying: the device was designed around that one, and the drawing above is how the other one sits in it.
- Lithium (CR2, 3 V) runs at 3 V, roughly double the nominal of the alkaline and silver classes. Of the 26 lithium cells here whose envelope the maker publishes, 3 share that envelope with an alkaline or silver cell.
What the codes and the sheets add
CR2 does not encode its size, so only the sheet says it; CR17345 does not encode its size, so only the sheet says it. Beyond size and voltage, the sheets say this: CR2 is rated from -40 C (-40 F) to 60 C (140 F), CR2 weighs 11 g, CR17345 is rated from -40 C (-40 F) to 60 C (140 F) and CR17345 weighs 16.5 g.
Telling them apart in the hand
The code is printed on the flat face of each: CR2 on one, CR17345 on the other. Stood side by side, CR17345 is 7.5 mm deeper, about 1.28 times the height of CR2, which a caliper reads at once and a ruler barely shows. Across the face CR17345 is 1.4 mm wider, and that difference alone decides whether it enters the opening at all. If the old cell is gone and the code with it, measure the holder instead: its depth and its opening are what this page compares.
Names on the package
CR2 has no other Energizer part number, and other brands sell it as DLCR2 and KCR2; CR17345 also appears as 5018LC, 123 (EL123) and ELN123 in Energizer's own part numbers, and other brands sell it as CR123A, 123A and DL123A. Energizer lists both, which says what is on the shelf under these numbers and nothing about who else still makes them.
Looks the same, and is not either of them
Rechargeable and other-chemistry cells are made in these sizes too. They enter the same two holders and differ in voltage or chemistry, so the label is the only check.
- 15270 — rechargeable lithium-ion at 3.6 V, and up to 4.2 V straight off the charger, against the 3 V of CR2, a higher voltage class. The same 15.6 x 27 mm; not a substitute.
- 16340 — rechargeable lithium-ion at 3.6 V, and up to 4.2 V straight off the charger, against the 3 V of CR17345, a higher voltage class. The same 17 x 34.5 mm; not a substitute.
- RCR123A — rechargeable lithium-ion at 3.6 V, and up to 4.2 V straight off the charger, against the 3 V of CR17345, a higher voltage class. The same 17 x 34.5 mm; not a substitute.
Which one to buy
Buy the code printed on the old cell or named in the manual. Neither stands in for the other: the shapes differ by more than the 0.3 mm a contact absorbs. Both pages carry the full figures and sources: CR2 and CR17345.
Before you swap anything
Everything here is computed from published dimensions and nominal voltages. That answers whether a cell enters the compartment and whether the voltage matches on paper. It does not answer what your device does with the difference, and it cannot: a cell that fits can still be the wrong cell.
One more limit, and it is the biggest. This site reads a single manufacturer’s catalog. When a page says a designation is not listed, that means Energizer no longer offers a part under it — not that nobody makes the cell. Other makers may still sell it, and for common sizes they usually do.
A voltage difference is one relation between two cells, and this page prints it from the cell it is about — in every table on the page, including the one listing cells no longer made. A figure always belongs to the cell whose voltage is printed beside it: a cell that runs lower than this one carries a minus here, one that runs higher carries a plus, and two cells at the same nominal voltage carry zero. Meet the same pair on the other cell’s page and the sign is the other one, with the figure taken against that cell instead of this one; where the two run at the same voltage, both pages print zero. The class beside the figure is not read off that figure directly. It is decided on the gap itself, taken against the higher of the two nominal voltages, so one pair of cells gets one class whichever page you meet it on: counted from this side the boundary of the class that still runs falls at 20.0% below and 25.0% above, which is the same gap divided once by the larger nominal and once by the smaller. What genuinely differs between the two directions is the consequence, and the words carry it: a cell that runs low makes a calibrated instrument read below true, and a cell that runs high makes it read above.
3 things this site cannot see. Whether the contacts reach a shorter cell. Whether the device was calibrated for a chemistry that holds its voltage flat, which silver oxide does and alkaline does not. Whether the equipment tolerates the higher current a different chemistry can deliver. Rechargeable cells are never a drop-in for primary cells regardless of size.
Where these numbers come from
Dimensions, voltages, chemistries and capacities are published by the manufacturer and reproduced without change. Everything else on the page is ours, computed from those figures: whether one cell fits where another sat, how far apart their voltages are, stored energy and energy per cubic centimeter, the rank within a shell, and the check of the designation against the measured size.
Fit is decided within 0.3 mm on every axis, which is the order of a contact spring's travel. Voltage classes are decided by consequence, not by roundness, and they are decided on the gap between two nominal voltages taken against the higher of the two: 2.0% or less of it is the same working voltage, 6.0% starts to matter to a calibrated instrument, and past 20.0% it is a different class altogether. Measuring the gap against the higher figure is what makes the verdict the same from either cell’s page, while the printed percentage stays counted from the cell you are reading about. Cells with identical stored energy share a rank instead of being ordered arbitrarily.
Ranking uses capacity times nominal voltage, because capacity alone is not comparable across chemistries: 150 mAh at 3 V is twice the energy of 150 mAh at 1.5 V. Neighbors are chosen by measurement and never alphabetically, because two cells filed next to each other by name usually have nothing in common. A blank in any table means the maker publishes no figure, which is not the same as zero.
Source: Energizer technical data, retrieved 1 September 2026.