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03-02-2018, 04:40 AM   #1
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P6x7 batteries - PX28 v PX28L?

Hi All,

Is there any significant difference between the PX28 & PX28L (Lithium) batteries? The PX28's seem to be variously described as Silver Oxide or Alkaline (i.e. both 4SR44 & 4LR44 replacements) but both using 'PX28'. The PX28L appears to be a Lithium battery that should have a longer shelf-life and better cold temperature performance.

Any ideas?


03-02-2018, 07:07 AM - 1 Like   #2
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Silver oxide batteries have a better discharge curve (constant voltage output for almost the entire life of the battery) and better capacity than alkalines so I'd definitely avoid alkalines.

Lithiums also have a pretty flat discharge curve but their operating voltage is slightly lower than silver oxide (just a bit under 6V instead of a steady 6.2V).

The light meters in some cameras can be very sensitive to battery voltage but I don't know if the 6x7 is among them.

If you do try lithiums, double check the accuracy of the 6x7's light meter before running a bunch of film through the camera. And periodically double-check meter accuracy as the lithium battery ages and it's voltage drops.
03-02-2018, 08:16 PM   #3
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The Pentax 67/6x7 is not designed to operate on lithium batteries. Silver oxide 6v batteries or alkaline 6v equivalents (4SR44 & 4LR44 replacements as you mention) are as much as is needed and nothing else.

Cold temperature performance of these cameras is more an issue of 'cold sink' rather than a problem with the battery, where cold works its way into the camera and can affect moving mechanisms.
03-03-2018, 10:52 AM   #4
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These are the silver oxide ones I use and I can get them locally, albeit at a higher price than online:



03-04-2018, 11:07 AM   #5
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Thanks All,

I've gone for the Varta PX28 4SR44 (some web sites seem to suggest it's a 4LR44 equivalent - which was confusing me) from an on-line film seller (I can't find them locally anymore). I'm looking for the most appropriate battery and it looks like the V28PX is it.

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