PX640 battery adapter for Minolta Hi-Matic E, F & Olympus 35 EC

• Replacement for the obsolete PX640: converts a standard zinc-air cell type 675 (PR44) to the PX640 format.
• A clean solution instead of DIY: fits in the battery compartment like the original PX640, with no makeshift solution required.
• Keeps the voltage constant: zinc-air cells provide a chemically stable voltage of approx. 1.4V instead of the initially too-high, declining 1.5V of alkaline batteries.
• Correct exposure without recalibration: the 1.4V is close enough to the original 1.35V for the light meter to measure correctly.

Compatibility

Suitable for various cameras, including:

• Canon: Canodate E, Canodate E-N, Cine Canonet 8, Date-Matic, Motor Zoom 8 EEE [...]
• Fuji: Date, GA (Rangefinder), GE, GER [...]
• Minolta: Hi-Matic 5, Hi-Matic CS, Hi-Matic E, Hi-Matic ES, Hi-Matic F, Hi-Matic FP [...]
• Olympus: 35 EC, 35 EC2, 35 ECR, 35 ED [...]
• Pentax: 1°/21° Spotmeter, 3°/21° Spotmeter, Spotmeter FL, Spotmeter I, Spotmeter II, Spotmeter III [...]
• Yashica: Electro 35 FC, Electro 35 GX, Lynx 14E, Lynx-5000E [...]

Not sure whether the battery fits your camera? Here is a complete list of all cameras compatible with the PX640 battery type.

What's included

• Standard: 2x PX640 adapters + 6x type 675 button cells
• Complete: 2x PX640 adapters + 6x type 675 button cells + 1x Universal Light Seal Set including mirror damper + 1x Extra Battery Pack (type 675) + 1x Film Memo Holder (120 Film Carton Holder)

Technical details

• Material: technical plastic
• Suitable for: type 675 (PR44) zinc-air battery
• Replacement for: PX640, E640N, V640PX, MR52, NR52, PX13
• Voltage: approx. 1.35V–1.4V (chemically stable)

Description

The PX640 adapter replaces the PX640 mercury battery, whose constant 1.35V output was the basis for many classic cameras such as the Minolta Hi-Matic E and the Olympus 35 EC. These batteries have no longer been available for decades. The adapter converts a standard type 675 (PR44) zinc-air cell to the PX640 housing format—ready to use without modifying the camera.

Zinc-air cells maintain a constant voltage of approx. 1.4V throughout their discharge curve. This is close enough to the original 1.35V to operate the light meter of most cameras correctly without recalibration. Alkaline replacement batteries, by contrast, start at 1.5V and steadily lose voltage, resulting in inaccurate readings. The adapter itself is purely mechanical and passes the current through directly.

Frequently asked questions

Where can I buy replacement type 675 cells? Type 675 cells are common hearing-aid batteries and are available at any drugstore (dm, Rossmann & Co.).

Why not use an alkaline cell? Alkaline batteries start at 1.5V and steadily lose voltage, which causes inaccurate readings. Zinc-air cells remain chemically stable at approx. 1.4V.

Do I need to have the light meter recalibrated? No. The approx. 1.4V is close enough to the original 1.35V for the light meter in most cameras to operate correctly without recalibration.

Which battery types does the adapter replace? PX640, E640N, V640PX, MR52, NR52 and PX13.

How many adapters are included? The Standard version includes 2x PX640 adapters and 6x type 675 button cells.