Pentax 645 lithium battery

Discussion in 'Medium Format' started by paula_swaim, Aug 12, 1999.

  1. [I recently purchased a used Pentax 645 in excellent plus condition. I don't know how old it is, but I wanted to change the lithium battery so that it wouldn't die on me unexpectly. I thought that the lithium battery was vital in its function, but apparently the camera will function fine without it and use the 6-AA batteries.
    Anyway, I opened the bottom chamber with tweezers, took the old battery out, put a new one in, and the liquid crystal display would not come on. It's as if there's no battery in there. I changed them back and forth (the old and new, thinking perhaps the new battery was dead somehow) and tried everything, but the liquid crystal display doesn't come on. But I put the 6-AA batteries back in and the camera works fine anyway. The manual does say that this lithium battery is actually a backup source anyway.
    Does anyone know why the lithium battery (both of them) will not work? Perhaps the contacts are not clearly connecting to the battery somehow. It worked fine until I changed it. The camera seems perfectly functional, meter and all, without it anyway. I'll make sure not to let the main batteries completely die in the middle of a roll though. Why would Pentax make such a stupid design anyway where they claim you need to bring it to their service center to replace?
    Any advice from people who have changed the lithium battery themselves would be greatly appreciated. Maybe there's something I didn't do right when changing it.
    Feel free to email me privately as well. Thanks in advance.]

    I recently posted about the problem I thought I was having with my Pentax 645 lithium battery. Since it did not work, I removed it from the camera and closed the chamber. Now there's no lithium battery, yet it still works perfectly. I really don't see the importance of it anyway. I will not let my batteries because exhausted and will change them when they are weak. In case of emergencies, there's always that manual rewind method anyway, but I don't plan on needing it. It doesn't seem that important that the liquid crystal display goes out while changing the batteries. I don't really see why Pentax would want to put it there in the first place. As far as I can see, no other medium format camera has a "backup" battery like that.
    I don't claim to know it all, but the camera appears to be working fine without the lithium battery. If anyone knows something I don't in regard to why the lithium battery might really "need" to be there, I'd be happy to hear from you. Thanks.
     
  2. What happens if you change batteries (without a backup) in the middle of a film? It wouldn't suprise me if your film counter reset, and your film spacing went wrong. The Pentax uses microprocessor and motor control to get 16 frames out of a 120.

    Why would you want to do this anyway? Do you doubt that Pentax has some good reason for using a backup battery? What does the manual say?

    Do you still have a problem with a blanked LCD display when you replace the Lithium? You don't make it clear in your second posting whether you're using both sets of batteries now or not.
     
  3. The backup batery is used so the camera can remember what picture it is on and the film speed that is set while you change batteries mid roll. (I think!). I haven't owned one of these for about 8 years!
     
  4. I changed a lithium myself in one of my 645's and didn't have a problem. Assuming the LCD still stays off if you reinsert the old battery, you could probably come to one of these conclusions:

    1. Both batteries are dead. Don't laugh, it happens!
    2. You reinserted the batteries upside down.
    3. Dirty contacts. A pencil eraser, used gently works well.
    4. Is the cover rethreaded all the way on? Sometimes a little extra pressure works (but not too much!)
    5. You broke something. Do any of the contacts seem loose?
    6. Finially, the worst. You shorted something out while using metal tweezers is a possibility. Hopefully this is not the case.

    The backup battery is obviously there only for when you change the 6 AA's. You have discovered that it's unnecessary under normal usage. Just make sure to reset your ISO when changing batteries. Don't, however, flame the camera because it has a backup and other cameras don't. That's sort of bizarre.

    Rob
     
  5. The battery is a Lithium CR1220 and its really easy to replace.
    David Strachan
     

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