Battery type V74PX: Compatible cameras

The V74PX is a 15-volt alkaline cylindrical battery in the column format (approximately 34.9 × 15.1 mm), manufactured by Varta from the 1960s onward. The "V" stands for Varta, while Varta adopted the "PX" suffix as a generic photographic designation. Common equivalents are 504, MN154, BLR154, and 10LR54. Unlike the mercury-containing PX625, the V74PX never contained mercury; it was alkaline from the outset, which was sufficient for its typical applications (flash units, triggering electronics).

The V74PX primarily powered flash units and individual light meters from the 1960s and 1970s. Typical candidates from the compatibility list above:

• Flash units: Nikon BC-7 flash, Minox BC flash 'A' and 'B', Minox flash for AG-1, Rollei 16S flash, Yashica Flash-O-Set (I/II), Fuji/Fujica Rapid SF Flash
• Light meters: Gossen Sixtron
• Compact cameras: Voigtländer Vitoret F, Yashica E

Outside the photography world, the V74PX is also used in the Feinwerkbau LP90 air pistol, which is why the search term "LP90-Batterie" often appears online, even though LP90 is strictly speaking not a battery name but a pistol model.

Varta discontinued production of the V74PX years ago. Original Varta cells now only turn up as expensive, often aged stock on eBay or from specialist dealers; fresh cells in this format are practically no longer manufactured industrially. Individual third-party manufacturers such as Exell still offer the 504A as a functionally equivalent alternative, but sourcing it in Germany is cumbersome. For most collectors, an adapter solution using standard button cells is therefore the more practical option.

Because the V74PX consists internally of ten 1.5 V cells stacked on top of one another, it can be technically replicated cleanly with an adapter:

• Ausgeknipst V74PX adapter with 10× AG10 (LR54): Housing made of technical plastic in the exact dimensions of the original V74PX, filled with ten commercially available AG10 button cells, delivering exactly 15 V. AG10 (also known as LR54, 189, or 389A) is inexpensive and widely available—no Wein cell drama and no zinc-air expiration date. Available from us as V74PX adapter including 10× AG10.
• Exell 504A or NOS Varta V74PX: 1:1 drop-in replacement with no adapter. Advantage: insert it and you’re done. Disadvantage: high unit price, highly variable availability, and stored batteries may already be half-empty when collected.
• DIY with heat-shrink tubing + 10× LR54: Works in principle, but is fiddly and mechanically unreliable. The stack slips around in the battery compartment, and the contacts oxidize more quickly. Recommended only as a hobbyist solution.

No, and that is the crucial difference from the PX625 discussion. With the PX625, exposure metering depends directly on the voltage level, which is why the mercury cell’s constant 1.35 V was so important there. V74PX devices are different: flash units need 15 V only to charge a capacitor. Whether the battery supplies 15.5 V when fresh or 13 V toward the end only changes the charging time, not the function. The firing electronics of the Feinwerkbau LP90 likewise tolerate a wide voltage range.

Only the Gossen Sixtron is a true light meter whose reading can theoretically be affected by voltage drop, but in practice the effect is minor because the Sixtron was designed with a simple galvanometer circuit rather than a mercury-cell reference. A fresh alkaline V74PX cell is perfectly adequate here; for greater precision, it is better to compare the light meter with a modern spot meter.