Alternative to PX625 battery

[Pieter12]

I just became aware of the Varta V80H rechargeable NiMH battery. It delivers 1.2-1.3 volts. Would it be suitable as a replacement for the mercury PX625, rated at 1.35 volts? Has anyone used these?

 

[pbromaghin]

PX625 battery is 1.5 volts, so no.

The guy who converted my Minolta SRT-201 circuits put in a Vinnic L1560. It died and Google gives several equivalents. I just today I ordered this off Prime:

Amazon.com

 

[ags2mikon]

Why not just use the mr-9 adapter and use a 357 silver oxide battery? I'm using them in a lot of my old junk and they work fine.

 

[Pieter12]

Both of those batteries are 1.5 volts. That won’t work for meters without recalibration. The PX625 is 1.35 volts, the V80 is closer at 1.2-1.3 volts. I am aware of the Wein zinc oxide batteries but they don’t last long.

 

[pbromaghin]

Oops. Senior moment. I both forgot and remembered that the conversion allowed mine to use 1.5 instead of 1.35. Never mind.

 

[mshchem]

I just switched to a non-meter prism on my F. Problem solved

 

[4season]

That NiMH cell might be worth a try, as NiMH maintains fairly constant voltage through much of it's discharge cycle.

But I was puzzled by how cameras designed for mercury batteries sometimes lacked any sort of on/off switch, save for the photocell itself. And one such camera in my collection (Konica S3) even has a "Mercury battery only" sticker. Curious, I queried Microsoft's AI, and it said that mercury batteries can "recover" somewhat, in a way that other battery types don't. And maybe that's the #1 reason why Konica didn't simply modify their meter to use 1.5 volt alkaline or silver batteries: Other battery types likely would need more frequent replacements, and customers would complain.

 

[reddesert]

I have not tried it so have no answer to the original question. It's not very expensive, considering, so interesting to try.

The genuine MR9 battery adapter contains a diode (probably a Schottky diode) to drop the 1.5v 357 battery to around 1.3v. The voltage drop would depend on current draw, but people who use these generally report good results.

Most of the original cameras using mercury batteries used a CdS photoresistor as the photosensitive element. These can have resistance of hundreds of kilo-ohms to several megohms in the dark. So depending on the meter circuit, if you stored your camera away with the lens cap on or in a dark environment, the current draw of the meter could be down to microamp levels, and the mercury battery would last a long time.

I think the cameras labeled "for mercury battery only" were related to the favorable discharge curve of the mercury battery (fairly constant voltage until it dies, unlike alkalines), under the assumption the average amateur user wasn't going to replace their batteries until obviously dead. Many cameras of that era didn't have a battery check indicator.

 

[Paul Howell]

I might give it a try, although 625 will be too large for my Konica ts which a take mercury 675 the zinc air 675 fits just fine. At the end of a shooting session I take the zinc air out and tape over the air holes. Topcon Uni also uses 675. Pentax Spotmatic does not matter much almost any battery will work. I have cardboard sleeves that I made for my Minolta 101 and 102 so I might try the rechargeable. One odd note, my Miranda EEs, the screw in battery compartment door is so tight I had to drill holes for the zinc air to breath.

 

[KevinW]

I have several of these that I use with 675 zinc-air hearing aid batteries:

PX625 PX-13 replacement Nikon F Leica, Gossen, Canon etc

A re-usable adapter for true PX625 PX-13 compatibility. Buy online with PayPal USPS Worldwide. 1000's sold worldwide est.2004, Nikon,Leica,Gossen and many more.

www.paulbg.com

It might seem like a lot of money for a 'washer' but they are a perfect fit. I use them in a Luna Pro light meter, a Luna Six 3 light meter, a Pen FT camera and a Yashica Mat 124G. They fit and work perfectly.

As an aside, I've had the zinc-air batteries last anywhere from 3 to 9 months (never less than 3 months in any device). They are pretty cheap to buy however, and they can be found literally everywhere (I've even seen them in larger gas station chain stores).

As another aside, here is an article from the March '95 issue of PopPhoto testing Mercury, Wein Cell and off the shelf Zinc-air hearing aid batteries. They found no more that one third of a stop difference between all three when using a Luna Pro light meter.

 

[Disconnekt]

Ive been using a MR-9 adapter with a 386 battery in my Sears TLS & its worked fine with it, the film negatives have come out fine.

 

[2ndGenNikonian]

Seconding the MR-9. I use it for my Spotmatic. It does sometimes get a little fiddly and require a re-seating in the chamber, but it works just fine otherwise.

 

[Jbennett68]

I bought a pen FT recently off marketplace. There was an old PX 625 mercury battery that came with it. I figured there no way this battery is good but I put it in and boom. Meter is working. Months later and it’s still working.

 

[ags2mikon]

Mercury, the gift that keeps on giving.

 

[wiltw]

I bought a pen FT recently off marketplace. There was an old PX 625 mercury battery that came with it. I figured there no way this battery is good but I put it in and boom. Meter is working. Months later and it’s still working.

Help it...take it out if not using the camera!!!! And then get an MR-9 adapter, and use the mercury cell only as a 'gold standard' for comparison testing any other substitute against.

 

[benderscameracorner]

I bought a pen FT recently off marketplace. There was an old PX 625 mercury battery that came with it. I figured there no way this battery is good but I put it in and boom. Meter is working. Months later and it’s still working.

The mercury battery in my Nikomat FT is years - nay, decades old - and is still going strong and metering accurately. It'll be a sad day when it finally dies.
You can understand why camera manufacturers in the 60s and 70s spec'd them instead of alkaline/silver oxide batteries until they were basically forced to.

 

[Chan Tran]

The mercury battery in my Nikomat FT is years - nay, decades old - and is still going strong and metering accurately. It'll be a sad day when it finally dies.
You can understand why camera manufacturers in the 60s and 70s spec'd them instead of alkaline/silver oxide batteries until they were basically forced to.

Back then they could't design a metering circuit that doesn't depend on steady battery voltage. In the late 70's when they switched to silicon cell camera meters would read the same from 3V down to 2.5V or so.

 

[wiltw]

Back then they could't design a metering circuit that doesn't depend on steady battery voltage. In the late 70's when they switched to silicon cell camera meters would read the same from 3V down to 2.5V or so.

Wheatstone Bridge circuits were never Voltage dependent, they operated comparing Resistance values.
And the CdS cell used at the time are resistive devices with resistance changes in proportion to the amount of visible light. In fact, in my senior year in high school, my project for Physics class illustrated Wheatstone Bridge principle in action in a lightlevel-dependent circuit using CdS (Silicon Blue had not yet been invented!).

Why a 'constant' Voltage circuit was employed instead I have no particular insight. Perhaps someone else might elaborate.

 

[Saganich]

I use MR9 with silver oxide 1.55 battery in Rollei 35T. Matches my spot meter and lasts a while if I keep camera in case. The Varta V80H rechargeable reportedly works fine... but how do you recharge them??

 

[BMbikerider]

Or you could look at the website of a company called "The small battery company.co.uk" They sell an adapter the same size as a PX625 but you fit a normal silver 1.5v battery inside. the micro electric circuit inside the adapter reduced the voltage down to 1.35 exactly. I had one for a Olympus OM1n and it worked perfectly. I think they cost around £20 or around 28$ (I don't know the current rate of exchange so it may be slightly different.)

 

[skahde]

This topic comes up every once in a while. There are two questions to answer.
1. Does your camera or meter need 1.35 V or will it work with 1.5V? If yes, solution: You just need a physical adapter and/or a fitting silveroxide replacement-battery. If not continue below.
2. Can the camera be readjusted to work with 1.5V? Solution as above.
3. Your camera or meter needs 1.35 V and there is no easy way to readjust it to 1.5. Solution: Wein-Cell or MR-9 voltage-reducing adapter together with silveroxide battery.

And this is about as much as there is to say.

 

[halfaman]

Zinc air batteries are a pain in the arse due to the constant discharge, even with the camera off. I would look to any other solution before this.

 

[Disconnekt]

Or you could look at the website of a company called "The small battery company.co.uk" They sell an adapter the same size as a PX625 but you fit a normal silver 1.5v battery inside. the micro electric circuit inside the adapter reduced the voltage down to 1.35 exactly. I had one for a Olympus OM1n and it worked perfectly. I think they cost around £20 or around 28$ (I don't know the current rate of exchange so it may be slightly different.)

Thats the site where I got mine a few years ago.

 

[chuckroast]

This topic comes up every once in a while. There are two questions to answer.
1. Does your camera or meter need 1.35 V or will it work with 1.5V? If yes, solution: You just need a physical adapter and/or a fitting silveroxide replacement-battery. If not continue below.
2. Can the camera be readjusted to work with 1.5V? Solution as above.
3. Your camera or meter needs 1.35 V and there is no easy way to readjust it to 1.5. Solution: Wein-Cell or MR-9 voltage-reducing adapter together with silveroxide battery.

And this is about as much as there is to say.

The correct answer to this question when talking about 1.35V/PX625 batters is: MR-9 adapters.

I have adjusted some of my Luna-Pros for modern 1.5V batteries, but that is painful. Excel used to make a 1.5V silver battery that fit there just fine, but now they no longer are available, so I have to use a physical adapter to use the smaller 1.5V batteries anyway. So, the recalibration was kind of a waste of time.

I have had one camera, a Leica M6 Leica M5, recalibrated for 1.5V batteries but this is expensive and you still need a physical adapter if you want to use silver or lithium batteries (because alkalines are not a great choice).

 

[Nitroplait]

Zinc air batteries are a pain in the arse due to the constant discharge, even with the camera off. I would look to any other solution before this.

They last half a year on average and are dirt cheap.
Can’t imagine the pain you must feel with the battery life of your phone or digital camera