V74PX Battery Type: Compatible Cameras

The V74PX is a 15-volt alkaline stick battery in column format (approx. 34,9 × 15,1 mm), manufactured by Varta from the 1960s onwards. The "V" stands for Varta, and Varta adopted the "PX" suffix as a generic photo designation. Common equivalents are 504, MN154, BLR154 and 10LR54. Unlike the mercury-based PX625, the V74PX never contained mercury but was alkaline from the start, which was sufficient for its typical applications (flash units, trigger electronics).

The V74PX mainly powered flash units and a few light meters from the 1960s and 70s. 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 photo world, the V74PX also turns up in the Feinwerkbau LP90 air pistol, which is why you often find the search term "LP90 battery" online, even though strictly speaking LP90 is not a battery name but a pistol model.

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

Because the V74PX internally consists of ten stacked 1,5 V cells, it can be replicated cleanly from a technical standpoint with an adapter:

• Ausgeknipst V74PX adapter with 10× AG10 (LR54): Housing made of engineering plastic in the exact dimensions of the original V74PX, filled with ten standard AG10 button cells, delivers exactly 15 V. AG10 (also known as LR54, 189, 389A) is cheap and available everywhere: no Wein cell hassle, no zinc-air expiry date. Available from us as the V74PX adapter incl. 10× AG10.
• Exell 504A or NOS Varta V74PX: 1:1 drop-in without an adapter. Pro: insert and done. Con: high unit price, availability fluctuates heavily, stored stock may already be half empty when you get it.
• 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 contacts oxidise faster. Only recommended as a tinkerer's solution.

No, and that is the key difference from the PX625 discussion. With the PX625, exposure metering depends directly on the voltage level, which is why the constant 1,35 V curve of the mercury cell was so important there. With V74PX devices it's different: flash units only need 15 V to charge a capacitor: whether the battery delivers 15,5 V when fresh or 13 V towards the end only changes the recycling time, not the function. The trigger electronics of the Feinwerkbau LP90 also tolerate a wide voltage range.

Only the Gossen Sixtron is a true light meter where a voltage drop could theoretically affect the reading, but in practice the effect is small, because the Sixtron was designed with a simple galvanometer circuit rather than a mercury cell reference. A fresh alkaline V74PX cell is perfectly sufficient here; for greater precision, you're better off calibrating the light meter against a modern spot meter.