Pentax 645-can't get reserve battery cover off.

f/16 · Jun 19, 2013

I got the CR1220 reserve battery for the camera but can't get the cover off. I grinded down the ends of tweezers so they would go in the holes. Then I turned both clockwise and CCW, and it would not move. Anyone have experience with this?

spoolman · Jun 20, 2013

Pentax 645-can't get reserve battery cover off

Hello f/16: I found the service manual at this website:http://www.uscamera.com/pen645sm.htm. Its not free but $7.99 seems to be a very reasonable price. Or google Pentax forums for more help.

Doug

pentaxuser · Jun 20, 2013

Where on the P645 is the place for the reserve battery? I have a P645N and have never seen any mention of a reserve battery. The one you mention is a small coin type battery. What does it do? I had a look at the P645 specs on Pentax forums and the only battery mentioned is the 6xAA.

Thanks in anticipation of an answer

pentaxuser

spoolman · Jun 20, 2013

Pentaxuser: I believe the compartment for this battery is on the underside of the camera next to the tripod socket
and it powers the memory that holds all of the function programs for auto exposure, regular exposure etc.

Doug

ggervais · Jun 20, 2013

As per the Pentax 645 manual, page 71, Memory Power source, built in Lithium battery for exposure data can only be serviced/replaced at a Pentax Service Center.

G

pentaxuser · Jun 20, 2013

Thanks. I wonder at what point in time this battery needs to be changed, 5 years, 10 years, less, more? Maybe under normal circumstances it never needs changing, otherwise why make it a Pentax Service Centre job. You'd think it should be a simple DIY action to take out the old battery and replace with a new one.

pentaxuser

f/16 · Jun 20, 2013

I don't think the 645N has it-it's only on the 645. I read online somewhere that it is easy to replace. Maybe the battery cover on mine is stuck or something. I'd hate to have to send it to Pentax just for that

pentaxuser · Jun 21, 2013

f/16 said:
I read online somewhere that it is easy to replace. Maybe the battery cover on mine is stuck or something. I'd hate to have to send it to Pentax just for that

My sentiments exactly. However it might be worth a call to a Pentax service centre to make sure that what seems to be the way to do it, actually is. Risking a breakage will be even more expensive.

Somebody somewhere must have replaced the battery. You might try Pentaxforums as suggested. Most of the users seem to be "digis" but there are a few experienced users of P645s

Best of luck

pentaxuser

MarkF48 · Jun 21, 2013

I looked up an exploded view of the P645 in the service manual and is shown in the image below. The Lithium battery is indicated as T400. I'm trying to recall if I've taken that cover off, but if I get some time later today I'll take a look and give it a try.
I also can't recall if I purchased the service manual or "found" it on online. Age related "Can't Remember S**t"!

MarkF48 · Jun 21, 2013

Image with battery cover removed.

f/16 · Jun 23, 2013

Thanks for the last image Mark. Is that your camera? Did you take it off yourself? If so, do you turn it CW or CCW? Did you have to use alot of force to get it to turn?

Clovis Blevins · Jun 23, 2013

If it ended up getting an alkaline battery in there, it may be frozen by a corroding battery. A dead alkaline is a leaky battery. I've seen that more than once on K-1000's.

f/16 · Jun 23, 2013

Clovis Blevins said:
If it ended up getting an alkaline battery in there, it may be frozen by a corroding battery. A dead alkaline is a leaky battery. I've seen that more than once on K-1000's.

I sure hope not. But I think the reserve battery is still good. When you remove the AA pack and reinstall it, the settings stay the same. I just want to replace the reserve battery because I've had the camera 2 years and don't know how long it's been in there.

MarkF48 · Jun 23, 2013

f/16 said:
Thanks for the last image Mark. Is that your camera? Did you take it off yourself? If so, do you turn it CW or CCW? Did you have to use alot of force to get it to turn?

Yes got the cover off myself. CCW is the direction. This is the second time it's been off just to show what it looks like for this post. The first time it was pretty tight. What is important in removal is having a tool of sorts that can apply "torque" equally to both of the holes to turn the cover. I don't have the correct tool, but used a pair of diagonal wire cutters that had points sharp enough to get a grab on the holes being careful to not let it slip out of the holes. I'm' not sure if this would have been an appropriate tool... http://www.amazon.com/Spanner-Wrench-Stainless-Pointed-Slotted/dp/B004WLMIBW (I should get something like this for removal of retaining rings on lenses).

Yes this is my camera. A local photographer that had quit wedding photography had the Pentax 645 with 80mm lens on Craigslist stating it worked fine . Went to look at it and when I tried to pop the AA battery pack out it was stuck. Finally got it out to find a corroded mess. He sold me the kit for $30 do to the condition. Took some effort, but got the camera cleaned up and working again as can be seen below. I have several other medium format cameras, but I couldn't pass on a deal.

f/16 · Jun 23, 2013

Thanks again Mark. I don't know about spending $50 for the tool for a one time job. Maybe I'll get some $10 retainer ring pliers or take it to a local camera shop and see if they can change the battery. The serial # on mine also starts with 102. I was hoping you knew how old yours is because they're probably the same age. But if you bought it used I'm sure you don't know.

f/16 · Jun 23, 2013

I went to Sears and picked up some $10 snap ring pliers and got the job done. Thanks for all the help APUG members.

Robert Ley · Jun 23, 2013

Bill
I have two 645 with age unknown reserve batteries. Where did you get the correct battery?

f/16 · Jun 23, 2013

Robert Ley said:
Bill
I have two 645 with age unknown reserve batteries. Where did you get the correct battery?

I got it at Ace Electronics. I don't think you can get a CR1220 in Walgreens, CVS, or Wal Mart. They're not common. Try a specialty electronics store-the kind that sells parts for do it yourself projects. That's what Ace is, but I don't think they're nationwide.

Robert Ley · Jul 10, 2013

Just replaced the batteries in my 2 645's. I used the same slip ring pliers and got the batteries off the Internet from a place in the UK. Total for both batteries was less than 5$ and about 10 minutes of my time.

The batteries that were in the camera were I believe the original batteries and were still functioning. The cameras had to be 15y/o or more, so the batteries last a longtime.

Sent from my iPad using Tapatalk HD

warrenbruce · Aug 10, 2013

use the eraser end of a pencil warrenbruce

mklw1954 · Sep 6, 2013

I would like to replace this battery on my two bodies and have the batteries. Is the battery cover removal just a matter of turning the cover counterclockwise, grabbing the cover by the two holes with the pliers mentioned or getting the cover to turn using an eraser?

mklw1954 · Sep 8, 2013

I answered my question by unscrewing the cover off one of my bodies using the eraser-end-of-a-pencil method. I bought this body 5 years ago from KEH so I don't know when the batttery was changed last but I checked the voltage and it was 3+ volts, i.e., original voltage. I guess as long as you don't let the main AA batteries run down and draw on the reserve battery it lasts almost indefinitely. I will plan on replacing it every 5years just to be safe.

I need snap ring pliers to get the cover off my other body.

Thanks all for the info in this thread. It's a great camera and I plan to use it for a long time.

Pentax 645-can't get reserve battery cover off.

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