Battery type V74PX — compatible cameras

The V74PX is a 15-volt alkaline cylindrical battery (about 34.9 × 15.1 mm), produced by Varta from the 1960s — the "V" stands for Varta, the "PX" suffix was adopted by Varta as a generic photo designation. Common equivalents are 504, MN154, BLR154, and 10LR54. Unlike the mercury-containing PX625, the V74PX never contained mercury but was alkaline from the start — which was sufficient for its typical uses (flash units, release electronics).

The V74PX mainly powered flash units and some 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 photography world, the V74PX also appears in the Feinwerkbau air pistol LP90 — which is why the search term "LP90 battery" is often found online, although LP90 is strictly speaking not a battery name but a pistol model.

Varta stopped producing the V74PX years ago. Original Varta cells now only appear as expensive, often outdated leftover stock on eBay or from specialty dealers — fresh goods in this format are practically no longer manufactured industrially. Some third-party manufacturers like Exell still offer a functionally equivalent counterpart with the 504A, but obtaining it in Germany is complicated. For most collectors, an adapter solution with common button cells is therefore the more practical way.

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

• Ausgeknipst V74PX adapter with 10× AG10 (LR54): Case made of PLA+ in the exact dimensions of the original V74PX, filled with ten common AG10 button cells — delivers exactly 15 V. AG10 (synonymous with LR54, 189, 389A) is cheap and widely available, no wine-cell drama, no zinc-air expiration date. Available from us as V74PX adapter including 10× AG10.
• Exell 504A or NOS Varta V74PX: 1:1 drop-in without adapter. Advantage: just insert and done. Disadvantage: high unit price, availability varies greatly, stock items may already be half used when picked up.
• DIY with heat shrink tubing + 10× LR54: Works in principle, but is fiddly and mechanically unreliable — the stack slips in the battery compartment, contacts oxidize faster. Only recommended as a hobbyist solution.

No — and that is the crucial difference from the PX625 discussion. With the PX625, the exposure measurement depends directly on the voltage level, which is why the constant 1.35 V line of the mercury cell was so important there. With the V74PX devices, it’s different: flash units need 15 V only to charge a capacitor — whether the battery is fresh at 15.5 V or near the end at 13 V only changes the charging 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 voltage drop can theoretically affect the reading — but in practice, the effect is minor because the Sixtron is designed with a simple galvanometer circuit and not with a mercury cell reference. A fresh alkaline V74PX cell is completely sufficient here; for higher precision, better calibrate the light meter against a modern spotmeter.