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

• Replacement for the obsolete PX640: brings a standard type 675 (PR44) zinc-air cell to the PX640 format.
• A clean solution instead of tinkering: sits in the battery compartment just like the original PX640, with no homemade workaround needed.
• Keeps the voltage constant: due to their chemistry, zinc-air cells deliver a stable 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 that take the PX640 battery type.

Scope of delivery

• Standard: 2x PX640 adapter + 6x type 675 button cells
• Complete: 2x PX640 adapter + 6x type 675 button cells + 1x universal light seal set incl. mirror damper + 1x extra battery pack (type 675)

Technical details

• Material: engineering plastic
• Compatible with: type 675 (PR44) zinc-air battery
• Replaces: 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 1,35 V many classic cameras such as the Minolta Hi-Matic E or the Olympus 35 EC were designed for. These batteries have not been available for decades. The adapter brings a standard type 675 (PR44) zinc-air cell to the housing format of the PX640, so it can be used without any modifications to the camera.

Zinc-air cells keep their voltage constant at approx. 1,4V throughout the 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 with an initial voltage of 1,5V and a steadily dropping voltage, on the other hand, lead to metering errors. The voltage comes from the cell; the adapter only provides the contact to the battery compartment.

Frequently asked questions

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

Why not an alkaline cell? Alkaline starts at 1,5 V and drops steadily, which leads to metering errors. Due to its chemistry, zinc-air stays constant at approx. 1,4 V.

Do I need to have the light meter recalibrated? No. The approx. 1,4 V is close enough to the original 1,35 V for the light meter of most cameras to work correctly without recalibration.

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

How many adapters are included? In the Standard variant, 2x PX640 adapters and 6x type 675 button cells.