PX24 Battery: Compatible Cameras

The PX24 (also sold as Eveready 532, V24PX, A24PX, EPX24 or 2LR50) is a cylindrical 3.0 volt alkaline battery made up of two 1.5 V alkaline cells wired in series. It has a large snap connector at each end and measures roughly 16.8 × 42.4 mm. Mallory, Eveready, Varta and Duracell made it from the 1960s onwards, and Exell still produces it today as a specialty battery (A24PX/532). Important: Unlike the better-known PX625 or PX27, the PX24 is not a mercury cell. It was an alkaline battery from the start, so it isn’t affected by the mercury bans in the EU Battery Directive 2006/66/EC.

The PX24 was used mainly in Polaroid Land packfilm cameras from the late 1960s and the 1970s. The Automatic 103, 104, 125, 135, 210, 215, 315, 320, 330, 420, 430 and 440, plus the Countdown 70 and M60, run on a single battery. The Automatic 335, 350, 360 and 450, plus the Countdown 90 and M80, need two (one for the shutter, one for the development timer). The Colorpack M6 and “The Clincher” take the PX24 too. You’ll find every model in the table above. Important: The similar-sounding Polaroid Automatic 100, 101, 102, 220, 225, 230, 240, 250, 340 and 355 do NOT take the PX24/532. They need the 4.5 V PX19/531 instead. People mix these up all the time.

The big battery makers no longer produce original PX24 batteries. You can still get them in two forms, though:

• Specialist new production (Exell A24PX / 532): US manufacturer Exell Battery still makes the original form factor today as an alkaline battery. You can find it through photo specialists and online retailers, though usually at a much higher price than standard batteries.
• Battery adapter with standard button cells: An adapter in the PX24 format that takes two ordinary 1.5 V button cells (LR44/SR44) inside and has the correct snap connectors. The upside: it’s inexpensive, you can buy new cells for it again and again, and standard batteries are sold everywhere. Available at Ausgeknipst as the PX24/532 Adapter 3V.

There are several ways to go with the PX24, each with its own strengths and weaknesses:

• Exell A24PX (original form factor): A direct replacement in the original format, alkaline chemistry, 3.0 V. Plug and play with no adapter, but relatively expensive and less widely stocked. The drawback, as with any alkaline battery: the voltage drops steadily as it discharges.
• PX24 adapter with 2x LR44 (alkaline): Inexpensive, standard batteries available everywhere, nominal 3.0 V. The drawback: the voltage drops steadily, and once the cells start to tire, the meter readings fluctuate.
• PX24 adapter with 2x SR44 (silver oxide): Higher capacity than LR44, a much more stable discharge curve, nominal 3.1 V. Slightly more expensive than LR44, but clearly the better choice for the light meter, because the voltage stays constant over almost the entire service life.
• 3 V lithium cell (CR type) in an adapter: Very long shelf life (~10 years), exactly 3.0 V, an extremely flat voltage curve. The drawback: the cell’s shape only fits special adapters, and not every Polaroid Land camera has enough room for a larger CR cell.

On Polaroid Land cameras with electronic automatic exposure, a voltage higher than the specified 3.0 V makes the CdS meter read more light than it should and close the shutter sooner. The result is slight underexposure. Conversely, a voltage that’s too low leads to overexposure. That said, the exposure electronics in pack film Land cameras are fairly tolerant: in practice, the difference between 3.0 V (2x LR44) and 3.1 V (2x SR44) usually stays within the film’s latitude. Like color negative film, Polaroid pack film handles overexposure better than underexposure, so a slightly low voltage tends to be the lesser evil.

Even more important than the absolute voltage, though, is consistency across the discharge curve: alkaline cells (including the original PX24) lose voltage steadily and give fluctuating meter readings over their lifetime. Silver oxide (2x SR44) holds its voltage steady through almost the entire discharge, which makes it the technically cleanest choice for any older camera with automatic exposure, regardless of whether the original was a mercury or an alkaline cell.