I am lucky enough to own a couple of Rollei 35 cameras. They are compact, handy and superb in image quality.
The Rollei 35 TE (also Rollei 35 SE) and Rollei 35 LED use the V27PX battery. It is quite an expensive battery. Also, it is a mercury battery toxic to our environment. There are some silver oxide replacements in the market. They are also not cheap. You may check an updated reference price here.
V27PX replacement can be S27PX, EPX27, 4NR43, KX27, HS3C. The replacements are all 6V batteries.
The original V27 PX is a 5.6V battery which is very rare nowadays. The available replacement is a 6V battery. The 0.4V difference will not make any observable difference in the photos taken given that the metering of Rollei 35 are not in anyway weighted. It is just a CDS sensor averaging the lighting of the scene.
Instead of buying a costly 6V replacement. I diy a replacement by the very cheap LR44 batteries.
Four LR 44 batteries stack together is just exactly like a V27PX.
The tip of the V27PX is its negative.
In order to make the four LR 44 batteries stack together nicely, I cut a piece of paper and roll them together. I like recycling paper by rolling them.
Done. Just don’t forget the polarity of the diy battery when putting it in the camera.
Let me know if you like this idea.