Battery

PX625

1.35V mercury (legacy) button cell

PX625 (PX13 / MR9) was a 1.35-volt mercury oxide meter cell. Mercury cells are obsolete. Common modern options are Wein MRB625 zinc-air or an MR-9 adapter with a silver-oxide 386 / SR43W. Alkaline 1.5V lookalikes can fit and still meter wrongly. This is not a 6V 4LR44 / PX28 cell.

Chemistry: mercury_oxide_legacy
Voltage: 1.35 V
Diameter: 15.6 mm
Thickness: 6 mm
Used by: 5 devices

Common uses: Vintage camera light meters · Film SLR meters (OM-1 class) · Vintage light meters

PX625 Diagram

Brand-neutral outline — confirm the tray in your device.

Other names

Genuine aliases and pack labels for this battery — not substitutes of a different chemistry.

PX13 · MR9 · EPX625 · RM625 · MRB625 · Wein MRB625

Related codes

Same battery / other names

PX625MR9

Also sold as

MR9 is another trade name in the PX625 / PX13 mercury meter cell family

PX625PX13

Also sold as

PX13 is a common alternate label for the same 1.35V mercury meter cell family as PX625

PX625EPX625

Also sold as

EPX625 is a retail / regional label in the PX625 mercury meter family

Commonly confused with

PX6254LR44

Not a substitute

Different voltage and form factor — 6V photo stack vs 1.35V mercury meter cell

PX625SR43

Not a substitute

MR-9 adapters often take silver-oxide 386 / SR43W — not a bare drop-in for PX625 without the adapter

Size

15.6 × 6 mm

Device-specific caveats

From manufacturer-backed notes on devices that use PX625 — not generic advice.

Keep button cells away from children.

Devices using PX625

Used in

Film cameras5 devices

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PX625 replacement optionsCompare

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Testers & chargers

Optional tools that fit this cell type — only where the chemistry allows. Separate from the battery answer.

Amazon links may earn us a commission. They do not change the battery answer.

Fluke 101 Digital Multimeter
Accurate open-circuit voltage and basic electrical checks
Docs Buy on Amazon More tools
Klein Tools MM400 Multimeter
General DC voltage checks including battery terminals
Docs Buy on Amazon More tools
AstroAI DM6000AR Digital Multimeter
Budget auto-ranging voltage checks
Docs Buy on Amazon More tools

Battery tester
Quick good / low / dead check for household cells
Crude check only — does not measure capacity under realistic load.
How to test a battery Buy on Amazon

Buy links are optional and separate from the battery answer.

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Need a PX625?

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Notes

Original 1.35V mercury oxide meter cell (also PX13 / MR9). Mercury cells are obsolete. Modern replacement paths include Wein MRB625 zinc-air and MR-9 adapters with silver-oxide 386/SR43W. Alkaline 1.5V lookalikes can fit and still meter wrongly. Not interchangeable with 6V 4LR44 / PX28.