Need battery for Canon Ftb: Mallory PX PX-625

I need a 1.3v M20 (#625) battery for my Canon Ftp. Mallory PX-625 and Eveready EPX 625 are listed as replacements. However none of these are mercury batteries and the voltage is usually 1.5 not 1.3.

Does it matter if the battery is not Mercury?

Does it mater if the nominal voltage is 1.5 and not 1.3?

This battery powers the built-in meter.

Why do I use this antique? Well I need to take ultra slow pictures (1 second) from a tripod and using a bulb operated operating button to avoid camera shake.

Nothing newer that I can afford offers these features.

All replies appreciated.

John Culleton

On 11/16/2015 03:33 PM, John Culleton wrote:
I need a 1.3v M20 (#625) battery for my Canon Ftp. Mallory PX-625

and Eveready EPX 625 are listed as replacements.

However none of these are mercury batteries and

the voltage is usually 1.5 not 1.3.

Does it matter if the battery is not Mercury?

Does it mater if the nominal voltage is 1.5 and not 1.3?


John Culleton


Wein makes a direct replacement. Sells for $5 USD or more, and lasts
about six months once the seal is broken.

Depending on the meter circuitry, the extra voltage may make your meter
reading be off. Or it may have no effect. Some meter circuits are
regulated, so any reasonable voltage can be used. Others require the
voltage from the battery to be correct. I don't know which is the case
for the Canon Ftp.

I do know that the Canon FX (1964-69) will read incorrectly. That's why
I use an external meter when "Sunny-16" doesn't cut it.

--
Ken Hart