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Power for memory of EOS 1v


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<p>I searched the PDF for my EOS 1v and although I found a lot of hits on "battery", I didn't find a good answer to my question.</p>

<p>Since the 1v can store shooting data for many rolls of film and it can also keep accurate date and time, does anyone know how that information is stored (and the TOD clock is powered) when there is no battery? Many similar devices have small button batteries for the clock and memory data but I've never heard mention of this for the 1v. Is there some capacitor which carries a "bridge charge" as batteries are changed? If you store it without batteries for a long time, are all the data lost?</p>


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<p>I don't know the answer to the question but there are several possibilities.</p>

<p>(A) It might use flash memory or some earlier form of non-volatile ROM (traditional EEPROM), in which case no battery backup is required. The 1v was released (I think) in 2000, at which time flash memory was commercially available. It wasn't cheap but you don't need multi GB to store all the 1v data (100K maybe?) so the cost would have been minimal. Flash memory does wear out but should be good for 100,000 write cycles.




<p>(B) There may be an internal non-user accessible internal battery. I seem to recall there were a few cameras like that which required taking the camera apart to replace the battery. It sounds like a really dumb idea, and it was. A data backup battery could easily last 10-15 years.</p>

<p>© As you say they could have a capacitor which could power the memory for quite a while during battery changes. It would of course eventually run down over the course of hours or days.</p>

<p> </p>

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<p>The EOS 1 has a CR1220 coin cell soldered onto the Main Flex B circuit board. The service manual says this may need replacing (by Canon at vast expense) after 5 years.<br>

I would not be surprised if the EOS 1V were the same, although I cannot see a backup battery, or a supercapacitor, mentioned in the parts catalog.<br>

I've never had a backup battery go dead on me, even with a T70.</p>


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  • 13 years later...

Sorry for reviving a very old thread, but I just discovered some interesting information regarding how EOS 1 cameras store information when the battery is removed. The EOS 1 had a back up battery to insure the information had time to be stored on the EEPROM. They changed the circuitry for the  EOS 1n (and I presume 1v) so that they could eliminate the back up battery.






Edited by mike_sowsun
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I just checked my EOS 1 and when the main battery is changed, it still retains the film counter and all Custom Functions. My EOS 1 is 32 years years old and I doubt it ever had the CR1220 back up battery replaced. 

I also checked my old EOS 630 and EOS A2 and they both retain the film counter and Custom function even when the battery has been removed or changed. I am pretty sure they do not have back up batteries. 

I wonder how the camera is able to do this? I suppose they all use EEPROM. Does anyone know? 


Edited by mike_sowsun
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