Pentax 645 lithium battery

<i>[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.

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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.

<p>

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?

<p>

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.

<p>

Feel free to email me privately as well. Thanks in advance.]</i>

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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.

<p>

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.

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.

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!

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

The battery is a Lithium CR1220 and its really easy to replace.

David Strachan