Index / 3LR50

3LR50

3LR50 — alkaline, 4.5 V, 16.8 x 49.9 mm. Not listed by Energizer, and nothing it still lists is the right voltage class for this compartment: CR17345 goes in and stands shorter, and runs 3 V — -33.3%, a lower voltage class. Not a substitute.

What fits the compartment, and what does not

Fit answers whether it enters the compartment. Voltage answers whether the circuit will notice. A cell that fits is not always a safe substitute.

Nothing Energizer still lists is the same depth. The one option below shares the diameter and stands 34.5 mm against this cell's 49.9, and every one of them is shallower, so each stands off the contact by the difference — a spring may take that up and a flat tab will not.

Also stamped 1306AP, 523, 1307AP, 531

Unlisted, and nothing that fits is the right class

Energizer no longer lists 3LR50 (also 1306AP), and nothing listed that fits the compartment is the right voltage: CR17345 goes in and stands shorter, but it runs 3 V against this cell's 4.5 V — 33.3% away, a lower voltage class altogether. A device built for this cell is not built for that one, and the compartment accepting it says nothing about the circuit surviving it.

What the chemistry changes

Everything above answers size and voltage. What it cannot answer is chemistry, and 1 other kind is in play here beside the alkaline this cell uses.

• Alkaline drops in voltage steadily as it empties, so a device calibrated for a flat discharge will drift as it goes.
• Lithium 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.

Where this compartment is unforgiving

3LR50 measures 16.8 x 49.9 mm, and what that compartment forgives is the question this page exists for. Nothing in the Energizer data this site reads matches it exactly; the nearest is CR17345. 3LR50 is nominal 4.5 V. A compartment holds a size; a circuit expects a voltage; nothing on the outside of the cell reports the second one.

Published capacity 650 mAh, which is what a swap costs or gains in run time before anything else is considered. Where the equipment matters, the maker of the equipment names the cell. That name outranks any cross-reference, this one included. 1 cell measures close enough to compare against it in the Energizer data this site reads, and 1 of it is still listed.

• The nearest is CR17345: it enters and sits lower and runs 3 V, wrong class.
• Energizer files it for North America, which is where the part is sold rather than where the cell will work.
• Energizer no longer lists 3LR50 at all, so whatever goes into that compartment next will be a substitution rather than a replacement.

Drawn to scale

Every published figure

11 figures are published, and one is not: impedance. The row is absent rather than estimated. It reached shelves as 523, 531 and EN133A.

Energizer files 1306A and EN133A under this designation as well, but its records give those a carbon zinc chemistry rather than alkaline. They are a different cell, not another marking for this one.

The maker’s records filed under this designation do not all publish the same outside size. The table prints the figure most of them carry; the rest publish a diameter of 17.1 mm under 1306A and EN133A and a height of 58.2 mm under 1307AP and 531. Where the records part company the package in your hand decides, and this page cannot tell you which record it came from.

2 rows in the table are not the maker's but ours: stored energy and energy per cubic centimeter. Everything else is reproduced without change.

What the datasheet does not say

Beyond size and voltage the sheet for 3LR50 is thin: 2 published figures below, and no impedance, no cutoff and no operating range at all. That silence is the maker's, not ours.

The part occupies 11 cubic centimeters and weighs 27 g. Capacity and voltage together put 2925 milliwatt-hours in that space. Energizer files it for North America.

Mass against volume

27 g filling 11 cubic centimeters. When the printing has worn off, a kitchen scale separates two cells of one envelope faster than a caliper does.

Where the part is filed

North America. That is a statement about the maker's distribution and not about where the cell works.

Is that a lot of energy?

Nothing else measured shares this shell, so the comparison has to go site-wide: 2925 milliwatt-hours in 11 cubic centimeters is 266 mWh per cc, denser than 35% of every cell measured here. Density is ours: the maker publishes capacity and volume and never divides one by the other.

A width the catalog keeps returning to

16.8 mm is a width this catalog keeps coming back to: 9 cylinders sit within half a millimeter of it, 3LR50 included.

1 of those one is still listed. Its 266 milliwatt-hours per cubic centimeter sit above 35 percent of everything here that publishes both a capacity and a volume. 1 of the 69 cylinders shares its 4.5 V exactly.

• 4LR52 — the next step down by volume: 10.3 cubic centimeters against this cell's 11.
• 3MR50 — the next step up: 11.3 cubic centimeters, 103% of this one.
• 2LR50 — 17.1 x 33.4 mm, 3 V, alkaline.
• 3MR50 — 17 x 50 mm, 4.09 V, mercuric oxide.

Names filed here that belong to another chemistry

The maker files 2 names under this designation with a different chemistry recorded against 2 ones. Same code, different insides, and the package is the only place that says which.

• 1306A — filed under this designation by the maker but recorded as carbon zinc, which is a different cell in the same shape.
• EN133A — filed under this designation by the maker but recorded as carbon zinc, which is a different cell in the same shape.
• 1306AP — a manufacturer part number for 3LR50, not a standard designation.
• 523 — a manufacturer part number for 3LR50, not a standard designation.
• 1307AP — a manufacturer part number for 3LR50, not a standard designation.
• The maker's own catalog carries 3 product lines under it.

The cell that differs only in depth

The code says the size, so the cells that get confused with 3LR50 are the ones that keep its diameter and change its depth. 8 cells share this diameter at depths from 21.5 to 99.8 mm, and every one of them enters the same opening.

It stands 1 of 1 in this envelope by stored energy. On a scale the difference shows before it shows on a caliper: this one weighs 27 g.

• 3MR9 — same diameter, 21.5 mm tall against this cell's 49.9: 28.4 mm shallower, which neither designation carries.
• 2LR50 — same diameter, 33.4 mm tall against this cell's 49.9: 16.5 mm shallower, which neither designation carries.
• CR17345 — same diameter, 34.5 mm tall against this cell's 49.9: 15.4 mm shallower, which neither designation carries.
• MR50 — 16 mm across at 1.4 V against 16.8 mm here, 0.8 mm apart: loose in this holder.
• LR50 — 15.8 mm across at 1.5 V against 16.8 mm here, 1 mm apart: loose in this holder.

What this page cannot tell you

3 of the 7 fields this site reads are empty for 3LR50: cutoff voltage, impedance and operating temperature. Everything computed from them is absent from this page rather than estimated.

The blanks are the same in all 3 records behind this designation, so they are the catalog's silence and not a merge losing a value. What is not missing is the envelope: 16.8 x 49.9 mm, published and checked against the designation itself.

• No cutoff voltage — so this page cannot tell you what the capacity figure was counted down to, without which the capacity is a number without a scale.
• No impedance — so this page cannot tell you whether the cell can drive a pulse, which is the whole question in a watch or a sensor.
• No operating temperature — so this page cannot tell you whether the maker claims anything at all below freezing.

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.

Cells measured next to this one

Nothing in this data is this exact size, but the diameter is a well populated one: 8 cells run from 21.5 to 99.8 mm deep, and this cell is one point on that scale.

• 3MR9 — 16.8 x 21.5 mm, 4.5 V
• 2LR50 — 17.1 x 33.4 mm, 3 V
• CR17345 — 17 x 34.5 mm, 3 V
• 4LR52 — 17.1 x 44.9 mm, 6 V

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.

Records that disagree behind this page

3LR50 is assembled from 3 catalog records, and they do not agree with each other on every field. Both sides are numbered below so the disagreement can be read rather than taken on trust.

1. [1] Energizer catalog record 649, listed as 523, obsolete in the snapshot. Technical data sheet: 523.pdf.
2. [2] Energizer catalog record 658, listed as 531, obsolete in the snapshot. Technical data sheet: 531.pdf.
3. [3] Energizer catalog record 807, listed as EN133A, obsolete in the snapshot. Technical data sheet: en133a.pdf.

Every figure above is reproduced from those records without change; the comparisons are ours and are described on the method page. Snapshot: Energizer technical data, retrieved 1 September 2026.

Putting this on a forum or a repair page? The same answer without the site around it — fit, voltage, chemistry and the limits that go with them — is at /embed/3lr50/. It loads nothing from anywhere else. Paste this:

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