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12-27-2019, 07:56 AM   #1
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645 battery holder

What ho one and all,

I have been a lurker for many years, but since the advent of digital, have 'sorta' retired my 67 and 645.

However, today I thought to give them a bit of a workout to ensure the mechanism is still working. 67, no worries but he 645 is a different story.

It still does what is says on the box but..................

The battery holder is made to be the weakest link in the chain and the pressure from the contact springs has basically caused it to fall apart. Have been searching eBay for another or even a battey grip but to date, no luck. Seems ridiculous either throw the camera away or have to buy another one, just to get a replacement battery holder.

Does anyone know of (may be?) a Chinese company or any other, that makes this item? Or is there a well known 'fix' that I have yet to discover?

Thanks, Happy New Year Year and toodle pip

12-27-2019, 10:21 AM - 1 Like   #2
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QuoteOriginally posted by Rekusu Quote
However, today I thought to give them a bit of a workout to ensure the mechanism is still working. 67, no worries but he 645 is a different story.

The battery holder is made to be the weakest link in the chain and the pressure from the contact springs has basically caused it to fall apart.
Does anyone know of (may be?) a Chinese company or any other, that makes this item? Or is there a well known 'fix' that I have yet to discover?
With care and patience, I've been able to clean and use Loctite 681925-6 Super Glue Plastics Bonding System with Activator, 2-Gram Tubes to fix my 645 battery holder.
Over the years, it has developed 5-6 cracks. Sparingly glue one crack at a time and use a clamp and let it set for a day. Then work on the next crack, etc.

When finished, I opted to only put in lithium AA batteries because:
a) They will last longer and thus not need to be swapped out as often which could damage the holder again.
b) They are lighter than alkaline equivalents.
c) I've had alkaline batteries swell and damage the holder in the past. I've yet to see that happen with lithium cells.

If that doesn't work, keep your eye out for a used 645 in "As Is" condition; it may have a fully functional battery holder.

In the meantime, you can always use your 645 in full manual mode, with or without the grip, and use the Sunny 16 rule, a light meter app, or a handheld meter for exposures.
With only one shutter speed it's the ultimate challenge, but with the right mindset, there's something very zen about it.
12-27-2019, 01:15 PM   #3
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Thanks for the reply. I may be able to 'reassemble' it but will use Araldite. However, some of the thinner bits have broken into so many bits, it will not be possible. Also, the bottom 'lock has fractured so is difficult to insert and extract from the grip.

Not sure the Lithium would make much difference as the problem appears to be pressure from the contact springs forces the thin plastic to distort. Lithium and AA will be the same length so the issue would be the same.

What I am wondering, since 6 X AA batteries is 9V, could it be possible to use a standard 9v battery? Surely 9v is 9v? But would that mess up the electronics in some way that I cannot foresee?

Even thinking about 3D printing a holder, but that is only a pipe-dream. Even if possible, the wall thickness would still be so thin as to be as rubbish as the original.
12-27-2019, 05:29 PM   #4
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A 9V alkaline should work, as it is internally a set of six 1.55V alkaline cells. However, the battery lifetime relative to the 6 AA cells will be proportional to their relative volumes. Also it is necessary to be sure that the normal six alkaline batteries are all in series and that there is no tap (at 4.5V say) going to the camera.

There is a battery helper module intended for cold weather that connects to the 645N. This holds a set of AA batteries. The holder can be kept from the cold inside one's jacket. It connects to the camera via a cable. I don't know if the 645 has an aux battery socket such that it would work, however, the formal name in my 645N Operating Manual is "Remote Battery Pack 645" (page 69). Many are available from eBay sellers.

My electronic copy of the 645 Operating Manual, on page 4, shows an "External Power Socket" under the grip. I suspect this might be compatible. I don't see the Remote Battery Pack mentioned, however, in the accessories region of the manual.

The manual for the Remote Battery Pack (attached) seems to illustrate the 645, so that is further support.

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File Type: pdf pentax645powerpack.pdf (180.4 KB, 106 views)
12-27-2019, 09:27 PM - 1 Like   #5
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QuoteOriginally posted by kaseki Quote
A 9V alkaline should work, as it is internally a set of six 1.55V alkaline cells. However, the battery lifetime relative to the 6 AA cells will be proportional to their relative volumes.

My electronic copy of the 645 Operating Manual, on page 4, shows an "External Power Socket" under the grip. I suspect this might be compatible. I don't see the Remote Battery Pack mentioned, however, in the accessories region of the manual.
The external power socket is an excellent idea. However, I think the 9V idea would be problematic. Typical AA batteries are in the 2000-3000 mAh range where 9V are more like 300-400 mAh.
12-28-2019, 12:23 AM   #6
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Again, thanks for the reply.

I am not familiar with the sockets on the 645N, but to the best of my knowledge, my 645 (old fashioned model) does not have an external battery socket. And although I have not used the camera in many years, for general out and about photography, having an external battery would be somewhat of a PIA (in my opinion.)

I was inspecting the holder closely and I may be able to reinforce it sufficiently. Seems to me, that the plastic is not really sufficiently strong to resist the spring forces being applied. Where is has broken is at either end of the battery contact spring applying too much pressure) and where the grip spring applies outward pressure.

Is there any way to reduce the spring pressure?
12-28-2019, 12:48 AM - 1 Like   #7
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QuoteOriginally posted by Rekusu Quote
to the best of my knowledge, my 645 (old fashioned model) does not have an external battery socket. And although I have not used the camera in many years, for general out and about photography, having an external battery would be somewhat of a PIA (in my opinion.)

Is there any way to reduce the spring pressure?
The 645 does have an external battery socket underneath the power grip. You must unscrew the socket cover to use it. And although it would be more cumbersome to use external power, I'd prefer that over the uncertainty or unreliability of a fragile battery holder. Another perk would be a lighter camera to carry if you could clip the external power to a belt.

If you were able to reduce the spring pressure, that could potentially cause an interruption of power with loose cells in the holder.
12-28-2019, 04:12 PM   #8
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QuoteOriginally posted by Rekusu Quote
It still does what is says on the box but..................

The battery holder is made to be the weakest link in the chain and the pressure from the contact springs has basically caused it to fall apart. Have been searching eBay for another or even a battey grip but to date, no luck. Seems ridiculous either throw the camera away or have to buy another one, just to get a replacement battery holder.
Does it still work? It seems like the sides of the "socket" that the battery holder goes in would provide some support against the springs. You could also try taping it to hold it together, you could put holes in the tape where it needs to make contact.

06-30-2020, 11:33 PM   #9
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So I joined this forum after getting a really good deal on a Pentax 645. Because I grew up in the '80s, I like the interface-and I'm excited to get out there and shoot some medium format!

However, the reason I got such a good deal on the camera is that the battery holder is completely missing. I gather from this thread and others that this holder is problematic, and very difficult to find. However, it looks like it's straight 9 volts into those two metal prongs in the bottom of the grip. It should be fairly trivial to fabricate a holder for six AA batteries into something that will fit the grip, and I don't care if it looks homespun as in ugly ;-) However I need to know the polarity of the prongs, so I don't put the power to it backwards and fry something.

It would be easy to figure out if I had the old holder, but I don't. Does anyone have a schematic of the holder or the pins?

Thank you in advance.
07-01-2020, 01:09 AM - 1 Like   #10
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QuoteOriginally posted by Boltonius Quote
It would be easy to figure out if I had the old holder, but I don't. Does anyone have a schematic of the holder or the pins?
Here is the service manual for the 645. Figure 5 has a wiring schematic. If this helps and you succeed, do the right thing and donate something to the .com this came from. I have no affiliation to their site.

https://learncamerarepair.com/downloads/pdf/pentax-645-sm.pdf
07-01-2020, 01:39 AM   #11
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And note that in standard electrical schematic style, the longer "plate" in the battery diagram is the positive plate. One hopes this was the understanding of whoever drew the schematic.
07-02-2020, 05:05 AM - 1 Like   #12
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Try looking for a 645 Remote Battery Pack, the battery holder is the same as in the camera. I found one new in the box, unused for $75.
07-02-2020, 08:17 PM   #13
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QuoteOriginally posted by longbow Quote
Try looking for a 645 Remote Battery Pack, the battery holder is the same as in the camera. I found one new in the box, unused for $75.
Ooh, that's a great idea! Thanks for the tip.

Also you could use the holder in your camera, then update the remote with a modern battery pack using a socket to charge it.
07-04-2020, 11:06 PM   #14
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Pentax 645 life hack: You can take a 9V alkaline battery and put it into the grip so its contacts are touching the metal bars, with the + terminal towards the outside of the grip. The camera will then load film and shoot, as long as you hold the battery in place with your thumb. Not a long term solution, but now at least I know the camera loads and shoots.

Also. found a MIB remote battery kit from Japan, spent the $119, then got a refund because Japan's mail service isn't mailing any packages out to anywhere because of Covid.

Hence the life hack above..
07-06-2020, 10:06 PM - 1 Like   #15
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QuoteOriginally posted by Boltonius Quote
Pentax 645 life hack: You can take a 9V alkaline battery and put it into the grip so its contacts are touching the metal bars, with the + terminal towards the outside of the grip. The camera will then load film and shoot, as long as you hold the battery in place with your thumb. Not a long term solution, but now at least I know the camera loads and shoots.

Also. found a MIB remote battery kit from Japan, spent the $119, then got a refund because Japan's mail service isn't mailing any packages out to anywhere because of Covid.

Hence the life hack above..
And now with pictures.. using two 9V batteries, a roll of electrical tape, and a cigarette packet I found in the trash.. creating a usable battery holder on the fly in front of O'Reilley auto parts because the only extant one online was broken, from the UK, and $100.

It works, and I have shot a roll and a half with it so far. Yes, it is ugly.
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