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06-11-2016, 01:58 PM   #1
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Converting battery holder to 14500 cells

Hello guys, I'm the happy owner of a K-50, that I like a lot, but I want more juice out of it, so I came up with this idea and want to ask your guys opinion about it.
I'm thinking of using the battery holder with 4 14500 cells of around 800mah each, using 2 in series and 2 in parallel that would give me the same voltage has the original battery, using protected batteries or adding a battery protection circuit would keep them safe, would this be feasible?
That would give me a total of 1600mah, and the option to buy quality batteries at a lower price then the original one.
Many thanks,


Nuno Almeida

06-12-2016, 04:38 AM   #2
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That's not nearly as exciting as the thread suggested. I thought you were going to go all Tesla and actually rig up 14,500 individual battery cells to power your camera.

As for your actual idea I don't see why it wouldn't work, but I'd be careful when experimenting with alternate power sources for your $500 camera. I'm an electronics engineer and I'm not sure I'd risk that.
06-12-2016, 05:13 AM   #3
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My doubt to be honest is the pinout, I think 2 are power, one for turning on the charger and one for readings, but I can't seem to find a schematic.
I think it would be a better alternative to Ni-mh, the voltage drop curve is just so much better, flat, with Li-ion
06-12-2016, 05:57 AM   #4
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As I remember, the K-50 is aware somehow that you are using the adapter and attempts to figure (or you can set) whether you are using alkaline or NiMH batteries. Lithium is not an option and so the voltage profile would upset its battery level calculations and result in underuse or worse an over-discharge and destruction of the lithium cells. Yiou would need to fool the camera into believing you were using a lithium internal battery rather than the AA adapter.

06-12-2016, 06:28 AM   #5
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QuoteOriginally posted by victormeldrew Quote
As I remember, the K-50 is aware somehow that you are using the adapter and attempts to figure (or you can set) whether you are using alkaline or NiMH batteries. Lithium is not an option and so the voltage profile would upset its battery level calculations and result in underuse or worse an over-discharge and destruction of the lithium cells. Yiou would need to fool the camera into believing you were using a lithium internal battery rather than the AA adapter.
That's what I'm worried about, and that's why I would like to know exactly what the third pin does, the camera only uses 3 the battery has 4,so the 4th one has to be specifically for the charger, I could easily add a contact to the holder with a bit of epoxy, but I need to know were to and how to connect it, I'm not worried about over discharge, has I could just use protected batteries, or add a simple 2s protection board, very inexpensive.
06-12-2016, 07:03 AM   #6
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It could be a temperature pin for monitoring temperature during charging. But unfortunately Pentax doesn't release circuit diagrams or detailed tech specs so it isn't public knowledge exactly how the battery identification happens.
06-12-2016, 01:20 PM - 1 Like   #7
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QuoteOriginally posted by ThorSanchez Quote
actually rig up 14,500 individual battery cells to power your camera.
Not just me with that line of thought too.

06-12-2016, 03:13 PM   #8
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lol indeed, the base of the idea is to use all available space, the battery holder allows that. If the camera could take a battery grip or I could buy reliable decently priced batteries I wouldn't think about this idea, but has it is now, pentax batteries are way too expensive and the second party ones I tried are crap
06-13-2016, 01:22 AM   #9
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Measuring the contacts on the battery I get between + and T 8.23, + and - 8.24, + and D 8.20, the results are consistent and repeatable, if I take out + of the equation there is no voltage reading between any of the other contacts, and Resistance goes has 10kohm between T and -, and 56.7kohm T and D, T .... looks like...Temp
This measured in a charged crap third party battery
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