Rollei 35 / 35S / 35T: Changing the battery (PX625 → Type 675 with adapter)

[N] Many Rollei 35 owners eventually face the same question: Which battery belongs in the small camera – and how do you change it correctly? The original PX625 mercury cells are no longer available. Fortunately, the old batteries can be reliably replaced: with type 675 (hearing aid batteries) in conjunction with a small rubber ring adapter. In this guide, I'll show you step by step how to do this, what the pitfalls are and how to get the light meter working reliably again.

[N] Why an adapter and why type 675?

[N] The Rollei 35 models were originally developed for PX625 mercury batteries. These had a very constant voltage over their lifespan – an advantage for analogue light meters. Today, mercury cells are prohibited. Type 675 hearing aid batteries (mostly zinc air) offer a similar voltage and discharge curve and are therefore the best modern alternative.

[N] Problem: Type 675 cells are slightly smaller than the old cells. That's why you either need a simple rubber ring adapter (ideal for Rollei 35) or a specially designed adapter for other camera models.

• [N] What you need

• [N] Type 675 hearing aid battery (zinc air is ideal)

• [N] Rubber ring adapter for PX625/type 675 (small O-ring)

• [N] 10 cent coin (or a suitable tool) to unscrew the battery cap

• [N] Q-Tip / cotton swab and contact cleaner

[N] Small screwdriver (to carefully roughen / straighten the contacts)

1. [N] Step-by-step: changing the battery

[N] Open camera

1. [N] Open the back of the Rollei 35 and slide out the film carrier – the battery is not located in the film area itself, but in a separate, screwed-in battery compartment.

[N] Remove battery cap

1. [N] The small cap of the battery compartment capsule is unscrewed counterclockwise. You can use a 10 cent coin or a small tool. The cap falls out, then the chamber is open.

[N] Remove old battery & check contacts

1. [N] Take out the old cell. Look at the two contacts: one fixed, one spring-loaded. With used cameras, it is advisable to clean the contacts.

[N] Contact cleaning

1. [N] If the contacts are oxidised or dirty, clean them carefully: lightly scratch with a screwdriver, put some contact cleaner on a cotton swab. Pull the spring contacts apart very slightly so that they exert firm pressure on the battery later.

[N] Adjust spring contact

1. [N] Modern replacement batteries are often a little thinner. Bend the small spring slightly outwards so that it makes reliable contact with the battery later.

[N] Prepare battery

1. [N] Insert the type 675 battery into the rubber ring adapter. Note: Zinc air batteries react with air; they have small openings and sometimes take a few minutes to deliver their full power.

[N] Insert correctly

1. [N] Polarity is important: with the Rollei, the positive side of the battery points downwards (towards the bottom of the camera). Insert the battery with the rubber ring into the chamber, put the cap on and screw it back on.

[N] Test

[N] Close the camera and check the light meter. If necessary, check the contacts again or that the rubber ring is seated correctly. In my test, the light meter works immediately after insertion.

• [N] Useful tips & frequently asked questions Not always. They need contact with air, so it can take a few minutes for them to deliver the full voltage. Some cells only deliver the full measurement after a short time.

• Can I cause damage? With the low voltage and capacity of the batteries, damage to the camera is very unlikely. Nevertheless: leaking old batteries can cause corrosion - remove old cells and clean the chamber.

• Why not silver oxide or alkaline? Silver oxide has a different discharge curve; some camera light meters may measure incorrectly as a result. Zinc air (type 675) comes closest to the old mercury curve.

• How long do the batteries last? Usually several months to years, depending on use and model. Rollei light meters can discharge faster if the meter is constantly activated - covering it or removing the battery is useful for longer storage.

Briefly summarised

• Rollei 35 / 35S / 35T: PX625 (mercury) is obsolete and no longer available.

• Use type 675 hearing aid batteries together with a small rubber ring adapter as a replacement.

• Check and clean contacts, bend the spring slightly, observe polarity (positive down).

• Zinc air batteries sometimes need air contact, so a few minutes to reach full power.

If you have any questions or are unsure which battery or adapter is best for your model: Write to us or search the shop for Rollei products. With this in mind - good light and have fun with your Rollei! Your team from Ausgeknipst