What is a PX400 battery?

PX400 was a 1.35-volt mercury cell. Mercury stock is obsolete. Wein MRB400 zinc-air is a common modern path. Not the same as PX625. See classic PX mercury replacements.

What is PX400 also called?

PX400 pack labels and aliases on this site include MRB400, Wein MRB400, S400PX. These are names for the same battery entity — not chemistry substitutes.

Is PX400 interchangeable with similar codes?

Related codes are not automatic equivalents. See Classic PX mercury cells and modern paths — match the code your device names.

Battery

PX400

1.35V mercury (legacy) button cell

S400PX is a pack label for PX400 — same battery, different name on the package.

Chemistry: mercury_oxide_legacy
Voltage: 1.35 V
Diameter: —
Thickness: —
Used by: 0 devices

Common uses: Vintage meters / cameras

Common questions

What is a PX400 battery?: PX400 was a 1.35-volt mercury cell. Mercury stock is obsolete. Wein MRB400 zinc-air is a common modern path. Not the same as PX625. See classic PX mercury replacements.
What is PX400 also called?: PX400 pack labels and aliases on this site include MRB400, Wein MRB400, S400PX. These are names for the same battery entity — not chemistry substitutes.
Is PX400 interchangeable with similar codes?: Related codes are not automatic equivalents. See Classic PX mercury cells and modern paths — match the code your device names.

Other names

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

MRB400 · Wein MRB400 · S400PX

Related codes

No related codes listed yet.

Devices using PX400

No devices listed for this battery yet.

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Classic PX mercury cells and modern pathsCompare

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Testers & chargers

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

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Battery tester
Quick good / low / dead check for household cells
Crude check only — does not measure capacity under realistic load.
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Battery storage / organiser
Keep spare cells sorted and prevent coin-cell shorts
Keep coin cells away from children.
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Notes

Legacy 1.35V mercury cell. Obsolete. Wein MRB400 is a common zinc-air path. Not PX625.