[BigMackCam]

Well, it happened to me... I bought a couple of "Duracell" Ultra Lithium 2CR5 batteries for one of my non-Pentax cameras via eBay at a seemingly excellent price. They arrived, and looked... well, pretty genuine, although the quality of the wrap-around label isn't the best - but could still have been genuine. They are dated to March 2019, and have a stamped-in date (of manufacture, I assume) of 2009/07. But having tried one of them, it discharged pretty quickly. By comparison, a Panasonic Photo Power 2CR5 I bought at a local store (for a considerably higher price, obviously!!) is lasting well. I suspect the Duracells are fake - no such thing as a free lunch, or a really cheap one that's any good So, I'm looking for recommendations on a UK source for genuine branded 2CR5 batteries at a sensible price - I'm happy to pay a little more to get the real thing. Any ideas, folks?

[Adam]

I suspect the Duracells are fake - no such thing as a free lunch

Or just old!

[BigMackCam]

Or just old!

Actually, I guess I should have amended my original post... This battery problem turned out to be caused by the Yongnuo 50mm lens on my Canon EOS-5 - draining the battery even while the camera was switched off. Since removing that lens and fitting the Canon 50mm f/1.8 STM, I've had the same battery fitted for weeks without any problem

[yucafrita]

Actually, I guess I should have amended my original post... This battery problem turned out to be caused by the Yongnuo 50mm lens on my Canon EOS-5 - draining the battery even while the camera was switched off. Since removing that lens and fitting the Canon 50mm f/1.8 STM, I've had the same battery fitted for weeks without any problem

That's interesting. How could this be the case? I have a Pentax Z-20 where I put a battery in last year and havent used it much since. I wanted to grab that thing on weekend and the battery was dead, which was even more annoying that I couldnt rewind the partly taken film (and of course no spare battery). There's a 28-70 attached with autofocus.

I wonder if the battery was almost dead on arrival but it was sealed and date was ok, too.

How can a lense drain the battery?

[BigMackCam]

With the Canon EOS-5, the common understanding (whether-or-not it's accurate, I can't say) is that the terminals that provide power to the lens (for autofocus operation etc.) remain active when the camera is powered down. Therefore, if the lens electronics draw any current when inactive, it will gradually deplete the battery. With the Yongnuo 50mm f/1.8 and 35mm f/2 I tried, both drained the camera battery while switched off, within 24 - 48 hours. I returned those lenses and now have a Canon 50mm f/1.8 STM, and an old Tokina 35-300 - neither of which have the problem (the Tokina has been sat on the camera for the last couple of weeks with only occasional use, and the battery is still showing as full).

EDIT: Going back to my original post, even the Panasonic battery I thought was lasting well actually drained within a couple of days with the Yongnuo lenses attached... It seems to be a known design flaw with those lenses. Shame, really, as I rather liked them

[yucafrita]

So the Pentax Z20 is not supposed to have similar issues with this or that Pentax lens? Just wondering, never heard of problems with Pentax, though...