Index / AC146X
AC146X
AC146X — zinc air, 8.4 V, 26.8 x 17 x 44.5 mm, known as a 9V cell. Not listed by Energizer, and nothing in its catalog shares this size.
Unlisted, and nothing in the catalog is this size
Energizer no longer lists a part under AC146X, and its catalog holds nothing else at 26.8 x 17 x 44.5 mm. That is the honest answer: a zinc air cell of this exact size is not something you can buy, and the closest options change either the depth or the voltage.
What a smoke alarm needs from a cell this size
In a United States home the commonest thing behind an 8.4 V cell is a smoke alarm, and an alarm is the one device that has to warn you before it stops. Energizer publishes 1100 mAh for AC146X.
7.2H5 fits the same clip and is rechargeable at 7.2 V. Its voltage falls off a cliff instead of drifting down, so the low-battery chirp an alarm is tuned to may never arrive. Alarm manufacturers name an acceptable cell on the unit and in the manual. Where a device is a safety device, that name settles it and this table does not.
- Energizer files it for North America, which is where the part is sold rather than where the cell will work.
- Energizer no longer lists AC146X at all, so whatever goes into that compartment next will be a substitution rather than a replacement.
Drawn to scale
AC146X, side elevation, from the published figures
Every published figure
11 figures are published, and one is not: impedance. The row is absent rather than estimated. It reached shelves as AC146X.
| Designation | AC146X |
|---|---|
| Chemistry | Zinc Air |
| Nominal voltage | 8.4 V |
| Length | 26.8 mm |
| Width | 17 mm |
| Height | 44.5 mm |
| Weight | 33 g |
| Volume | 19.6 cc |
| Capacity | 1100 mAh to 6 V |
| Stored energy | 9240 mWh |
| Energy density | 471 mWh per cc |
| In the Energizer catalog | No longer listed |
| Listed for | North America |
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.
Where the capacity figure stops counting
A capacity figure means nothing without the voltage it was counted to. For AC146X the maker counts down to 6 V, and 2 published figures sit beside it.
The part occupies 19.6 cubic centimeters and weighs 33 g. Capacity and voltage together put 9240 milliwatt-hours in that space. Energizer files it for North America.
- Cutoff voltage
- 6 V. The published capacity is counted down to this voltage; a device that quits higher up sees less than the whole figure.
- Mass against volume
- 33 g filling 19.6 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: 9240 milliwatt-hours in 19.6 cubic centimeters is 471 mWh per cc, denser than 80% of every cell measured here. Density is ours: the maker publishes capacity and volume and never divides one by the other.
More energy per cubic centimeter than most
AC146X packs more into its volume than most of what is measured here: 471 milliwatt-hours per cubic centimeter, above 80 percent of the corpus.
Its 471 milliwatt-hours per cubic centimeter sit above 80 percent of everything here that publishes both a capacity and a volume. 0 of the 50 boxes share its 8.4 V exactly.
- 4LR61 — the next step down by volume: 15.4 cubic centimeters against this cell's 19.6.
- 6F22 — the next step up: 20.3 cubic centimeters, 104% of this one.
Nothing else is stamped on this one
Nothing else is printed on AC146X in the Energizer data this site reads: one designation, no trade marking, no maker's part number, and no long form in the standard's table. A cell measuring 26.8 x 17 x 44.5 mm carries its whole identity in 6 characters.
Sold under the same household name
The household name is the trap here. 6 designations are sold as the same 9V as AC146X and do not all deliver the same voltage.
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 33 g.
- 1604LC — sold as the same 9V and rated 9 V against this cell's 8.4 V.
- 7.2H5 — sold as the same 9V and rated 7.2 V against this cell's 8.4 V.
What this page cannot tell you
2 of the 7 fields this site reads are empty for AC146X: impedance and operating temperature. Everything computed from them is absent from this page rather than estimated.
The blanks are the same in all 1 record behind this designation, so they are the catalog's silence and not a merge losing a value. What is not missing is the envelope: 26.8 x 17 x 44.5 mm, published and checked against the designation itself.
- 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.
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.
The record behind this page
Every figure on this page comes from one catalog record, number 724, and it is linked below. The sheet is the document the dimensions, voltage and capacity were read out of.
- [1] Energizer catalog record 724, obsolete in the snapshot. Technical data sheet: ac146x.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/ac146x/. It loads nothing from anywhere else. Paste this:
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