[Leica] Mercury, Alkaline, and Silver Oxide Batteries

["Kotsinadelis, Peter (Peter)" <peterk@lucent.com>]

The 3 batteries are different as follows:

Mercury have a constant 1.35v even as they expend their energy.  This
constant is why they were the prime choice in many cameras for metering
systems. They also have a 10+ year shelf life where as Alkalines are
generally 1/2 that at best.

Alaklines have a 1.6+ volts even though they indicate 1.5v per battery with
the drop off curve being slow and steep.  At the end of their life cycle
they will generally test about 1.35v where the mercury battery would
normally be.

Silver Oxide are a bit in the middle at around 1.55 volts.  They offer more
constant output, a linear drop off (not steep) and will provide a somewhat
longer life than alkalines.  Silver Oxide batteries offer a longer shelf
life than Alkalines.

Peter K

- -----Original Message-----
From: Dave Richards [mailto:dprichards@uswest.net]
Sent: Friday, June 18, 1999 2:09 PM
To: leica-users@mejac.palo-alto.ca.us
Subject: Re: [Leica] Mercury vs. Alkaline Battery


Where do silver oxide batteries fit into the equation?  That is, if I get
the adapter to use silver oxide PX76's in my Luna Pro what can I expect for
performance as they grow old?

Dave

>If I remember back to college physics, Voltage = Current/Resistance.  Since

>an analog camera lightmeter functions basically as a variable resistor, the

>error brought about by an increase in voltage should be linear, and a
simple 
{snip}
>they told me.  I have a Nikon FTn which was only "tweaked" to accept the 
>625A, so I have always made it a point to check it against a known meter
each 
>time before using it and reset the ASA if necessary.
>DT
>
>