PX625 rechargeable battery with USB-C charger

• Voltage close to the original: Operating voltage of 1,25–1,30 V instead of the excessive 1,5 V of an alkaline, correct metering with CdS light meters, no incorrect exposures on negative film.
• Direct replacement instead of an adapter ring: The V80H sits directly in your camera's battery compartment, without an MR-9 adapter and without a diode for voltage adjustment.
• Rechargeable instead of single-use: A V80H battery, rechargeable via USB-C, replaces expensive zinc-air cells that dry out after a few weeks.
• Ready-made charging station instead of DIY: Custom PCB, USB-C port, housing with spring contacts. Plug in, charge, done.

Safety notes

Please charge the V80H battery only in this dedicated charger. Charging indicator: the blue LED shows that the USB-C cable is connected. There is no battery-full indicator; a full charge takes approx. 9 hours.

Conversely: only the Varta V80H belongs in this charger; smaller NiMH button cells such as the V15H or V40H must not be inserted. The charging current is fixed to the 80 mAh of the V80H (C/7) and does not switch off when the cell is full. A V15H would receive a good five times this charge rate, a V40H twice as much. Both overheat and can leak.

• Insert the V80H upright into the slot. The side with the large + (marked VARTA) faces the + on the lid, the other side faces the −. The cell also fits in the wrong way round, so check before charging: wrong polarity can damage the cell and the charger.
• Do not insert disposable batteries.
• Do not charge unattended; charge on a non-flammable surface at room temperature and do not cover the charger. Protect from moisture and extreme temperatures.
• After charging, unplug the charger and remove the cell.
• Do not short-circuit the cell, open it or throw it into fire. Keep away from small children due to the risk of swallowing.
• The charger is an electrical device and does not belong in household waste, but at a collection point for waste electrical equipment.

Compatibility

Replacement for the 1,35 V PX625 mercury battery (IEC designation MR9). Suitable for various cameras and light meters, including:

• Canon: Canonet series (QL17, QL19, 28, G-III), F series (F-1, FT, FTb, FX), Demi / Dial series (Demi, Demi S, EE17, Dial 35 II) [...]
• Nikon: F series (F, F Photomic, FTN), Nikkormat / Nikomat series (FT, FTN) [...]
• Minolta: SR-T series (100-303, MC, SC, Super), SR series (1, 7, 100-505), Hi-Matic series (7, 7S, 9, 11) [...]
• Olympus: OM-1 series (OM-1, MD, N), 35 series (RC, RD, SP, DC), Pen series (F, FT, D2, EED) [...]
• Pentax: K series (K2, KM, KX), Spotmatic F, H series (H1a, H3v) [...]
• Rollei: 35 series (35, 35S, 35T, Classic; not 35 SE/TE, which need a PX27), SL35 series (SL35, SL35M, SL350), XF35 / A26 [...]
• Gossen: Luna-Pro / Lunasix series (Luna-Pro, Luna-Pro S, Luna-Six 3, Lunasix 3S), Sixtomat Electronic, Sixtar / Sixtar 2, Super Pilot / Super Pilot SBC [...]
• Sekonic: L-98 Micro-Leader, L-218 (Apex, Autorange), L-228 Zoom-Meter, L-248 Multi-Lumi, Marine Meter series (L-164, L-184C, L-1484) [...]

Light meters often need two cells, cameras usually just one: the Gossen Luna-Pro, Luna-Pro S, Luna-Six 3, Lunasix 3S and Sixtomat Electronic run on two. The Pro Pack contains two rechargeable batteries. Don't confuse them: the Luna-Pro F and Luna-Pro SBC run on a 9 V block battery, so this cell won't fit there.

Not sure whether the battery fits your camera?
Here is a complete list of all cameras and light meters that take the PX625 battery type.

Scope of delivery

• Standard: 1x USB-C charger + 1x V80H rechargeable battery (PX625-compatible)
• Pro Pack: 1x USB-C charger + 2x V80H rechargeable battery
• Pro Pack + battery compartment tool: 1x USB-C charger + 2x V80H rechargeable battery + 1x battery compartment coin tool for opening the battery compartment

Technical details

• Rechargeable battery: Varta V80H (Low Self-Discharge NiMH, 80 mAh)
• Nominal voltage: 1,2 V (according to the manufacturer)
• Operating voltage (plateau): 1,25 – 1,30 V
• Capacity: 80 mAh, enough for weeks at the microampere draw of a CdS meter
• Charging method: gentle slow charging (C/7) via USB-C
• Charging time: approx. 9 hours (charging overnight recommended)
• Charger material: engineering plastic
• Connection: USB-C, fixed 5 V without PD negotiation

Description

In short: The Varta V80H is a rechargeable replacement for the discontinued 1,35 V PX625 mercury battery (IEC MR9) and is charged via USB-C. With a working voltage of 1,25–1,30 V, it keeps your CdS light meter accurate, with no adapter ring and no diode, right in the battery compartment. Fits the Rollei 35, Leica CL, Olympus OM-1, Canon F-1 and Minolta SR-T, among others.

For a long time, the classic workaround for the 1,35 V PX625 mercury battery (IEC MR9) was an adapter with a diode that lowers the voltage. It was necessary because classic analog cameras such as the Rollei 35, Leica CL, Olympus OM-1, Canon F-1 or Minolta SRT were designed for exactly this battery. Since the production ban, there has been no replacement that covers voltage, form factor and shelf life all at once. The most common alternative (1,5 V alkaline) delivers too high a voltage, which leads to incorrect exposures, especially with CdS light meters.

The Varta V80H solves this problem with a working voltage of 1,25–1,30 V, which is much closer to the original. It is not an ordinary NiMH battery: the V80H comes from Varta's industrial “Robust” series (built for server RTC and medical technology) and uses LSD NiMH technology (Low Self-Discharge). Its self-discharge is comparable to the Eneloop series.

The idea of using a V80H as a PX625 replacement comes from Troeszter.net. Building on that, we developed a standalone product: our own PCB, USB-C instead of a lab power supply, and a housing with spring contacts.

On cameras like the Rollei 35 or Leica CL, the battery compartment sits in the film chamber, so every battery change means: film out. With the Pro Pack (2x V80H), you simply swap the battery every time you change film.

Frequently asked questions

“1,2 V is too little. The original had 1,35 V”

The 1.2 V in the datasheet is the nominal voltage that every NiMH cell carries. In the camera, what counts is the voltage under the tiny load of the light meter, and that is higher. Troeszter.net measured it in a Rollei 35T and 35S: freshly charged 1.30–1.32 V, after two weeks 1.27–1.28 V, after four weeks 1.25–1.27 V. The deviation from the original goes in the direction of overexposure, and negative film handles that easily.

“Does my light meter really measure correctly with it?”

Several people have checked this against an independent reference: Troeszter.net on the Rollei 35 at a standardized light table against the old mercury cell, Joshua Lowcock on his Minolta SRT 201 against the WeinCell (test report below), and a customer on his Voigtländer VF 135 against a Sekonic handheld light meter. All three got the same readings. Camera Talk writes that light meters he had considered defective after other makeshift solutions read again with the V80H. You can check it yourself with a gray card or an evenly lit wall: meter once with the camera, once with a handheld light meter or a light meter app, in bright and in dim light. If both agree within a third of a stop, it's fine.

“Isn't that expensive compared to zinc-air cells?”

In purchase price, yes. The cheapest option with the right voltage is a zinc-air cell in the universal adapter, €26 to €37 for one camera over three years (prices excluding shipping, as of September 2026). A zinc-air cell, however, starts aging as soon as you peel off the tab and is dead after a few months, even if you don't shoot. The rechargeable battery costs nothing more after purchase until it fades after about five years, and one charger is enough for all your cameras. With three regularly used cameras, it comes to around €68 after three years, on par with zinc-air (€58 to €91) and far below the WeinCell (€162 to €324) or three MR-9 adapters (€165 to €195). The full calculation is in the PX625 guide.

“Only 80 mAh capacity. That's not enough”

A CdS light meter draws microamps. At this current draw, the stable voltage plateau of the V80H lasts not hours, but weeks. 80 mAh is little for AA batteries, but for a camera button cell it is sufficient. In practice, depending on the camera, you recharge every few weeks to two months; Camera Talk gets one to two months with his cameras. A charge lasts longest when the camera is kept in the dark (see practical tips).

“But NiMH discharges on its own”

Standard NiMH loses 10–20% of its charge in the first few days. The V80H is not standard NiMH. As an LSD cell (Low Self-Discharge) from the Varta “Robust” series, it still retains approx. 80% of its capacity after one year at room temperature, comparable to the Eneloop series.

“Can I charge the V80H in my regular battery charger?”

No. What matters is the charging current, not the voltage. Varta specifies 7 mA over 14 to 16 hours as the standard charge for the V80H and 14 mA over 7 to 8 hours as the accelerated charge (datasheet). A charger for AA or AAA batteries is built for cells with several hundred to over a thousand mAh and delivers many times that. The small cell gets hot in it and can leak. The same applies to DIY solutions where the cell is held in an AA charger with clips or a cork. Our charger charges at about 11 mA, within Varta's specifications, and therefore takes around 9 hours.

“Can't I just use an alkaline and compensate with the ISO dial?”

The problem with alkaline is not so much that the voltage is too high, but that it drifts: it starts at just under 1,6 V and drops to about 1,2 V over its lifetime. So the metering error doesn't stay put: the correction that is right today will be wrong in four weeks. Then there's the direction: too much voltage means underexposure, and that is the one direction negative film doesn't forgive. In bright light, a fresh alkaline can leave you up to two stops short, because the CdS response curve is not linear. The V80H, on the other hand, holds its plateau at 1,25–1,30 V. Whatever deviation remains goes towards overexposure and is less than a third of a stop. You won't see that on negative film, and if your camera has a compensation dial, you set it once and leave it there.

“The light meter isn't responding. What should I do?”

Check the polarity, clean the contacts in the battery compartment and freshly charge the cell. If it still doesn't work, the fault may lie in the camera. Write to us and we'll help you narrow it down.

Practical tips

• Charging: Fresh out of the package, the V80H is only partially charged. Charge it fully once before first use, around 9 hours or overnight, and then disconnect it from power. The LED does not show when the cell is full; one hour on the charger is not enough. Afterwards, let the cell rest for 1–2 hours before it goes into the camera. The resting voltage stabilizes during this time.
• Inserting: Open the battery compartment and insert the V80H the same way as the original PX625, with the positive pole (+) where the device specifies. Close the battery compartment and check the light meter. Recharge as soon as the light meter reads unreliably or cuts out.
• Battery check: Many cameras (OM-1, Minolta SRT) have a battery check calibrated to 1.35 V. The V80H shows “empty” there even though the light meter works perfectly. This is normal.
• Cameras without an off switch: On the Rollei 35 and some other cameras, the light meter has no switch. The light meter draws current whenever light falls on the metering cell, even with the lens cap on, because the metering cell has its own window. Put the camera in a bag or a drawer between outings, otherwise it drains the battery even when you're not shooting at all.
• Cold: Below 5 degrees Celsius, NiMH becomes unreliable. For winter shooting in freezing temperatures, a zinc-air cell or alkaline + ISO correction is the better choice.
• Power source: The most reliable way to charge is with an old, simple USB power adapter with a fixed 5 V or a USB port on a laptop. Newer USB 3.2 and PD power adapters and many power banks first negotiate the voltage or shut off again at the tiny load. Then no current reaches the charger, and it doesn't charge. If the LED on the charger stays off, try a different cable as well. If it still stays off, write to us.
• Leica M5: The screw cap of the M5 fits tighter than on other PX625 cameras, so the V80H can jam there. If you can't get it cleanly into the compartment, use a type 675 zinc-air cell for the M5. It is smaller and fits directly into the M5 without an adapter.
• Leicaflex SL: The V80H does not fit here. The battery compartment of the SL is known to be tight; even an adapter just under 0.4 mm taller than the old PX625 keeps the screw cap from closing there. A tester tried the V80H in his SL for us: the cap does not catch. The SL works with the Wein cell MRB625.

Most PX625 cameras are over 40 years old. We accept no liability for defects in the camera itself; in that case, a service by a camera technician will help. During a break of several months, remove the cell from the camera, store it partially charged and recharge it every 6–12 months.

Detailed comparison of all PX625 alternatives (alkaline, zinc-air, Schottky adapter, V80H and DIY solutions) with measurement data, practical tests and community feedback: Go to the complete PX625 guide.

Independent video test

The US channel Camera Talk bought the set on its own and tried it out in four devices: Gossen Super Pilot, Nikon F Photomic, Rollei 35 and Contarex Super. In the video he states explicitly that he received neither a discount nor free samples from us. We are leaving his criticism as it is: the price, and the fact that the LED doesn't show when the battery is fully charged.

Video: Camera Talk, “A Rechargeable Alternative to the Mercury Cell” (English)

External test reports

Thomas Raatz of analoge-fotografie.net received the charger with two batteries from us for testing and labels his article as advertising. He describes how it handles in practice, including criticism: despite the guide groove, the cell can be inserted the wrong way round, and there is no automatic charging cut-off. Read the test report on analoge-fotografie.net

Joshua Lowcock received the Pro Pack with two batteries from us for testing and tried it out in his Minolta SRT 201. His result: with our battery, the light meter shows the same readings as with the WeinCell MRB625 he used before. The SRT's battery check still reports the cell as empty, because this check is calibrated to 1.35 V (see practical notes). Read the test report on joshualowcock.com (English)