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04-12-2010, 06:06 AM   #1
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Will the K-x run on two batteries?

Just wanted to check. Four NiMH batteries are good for at least a thousand shots. If it can run on only two it would save a little on weight and still be able to manage at least 500 shots, which is more than enough for me for several days' shooting.

So can it do that? Do we know if the batteries are connected serially or in parallel, or a combination?

04-12-2010, 06:19 AM   #2
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I would suppose that the batteries are connected in such a way as to deliver 6V. I don't have a specific reason for saying this, other than my K10D's battery pack is 7.4, and I image the K-x uses almost as much juice to get things going. That, and almost all devices that use multiple AA batteries do the same thing.

The problem with only using two is that the camera probably can't operate on just 3 volts, and even if it could, you'd need to put "dummy" pass-through batteries in two of the holes.

So in short, the answer is no.

EDIT: If you want to save weight, you'd need to decrease the amount of energy stored in the batteries without changing the stored voltage. Maybe adapt lighter AAA batteries (which are 1.5V just like AA batteries) to fit in AA-sized holes?

There are instructions on doing that here: http://www.instructables.com/id/Make-a-AAA-battery-work-as-a-AA-battery/

Not really sure how much weight you'd save though. I'm guessing not much.
04-12-2010, 06:23 AM   #3
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QuoteOriginally posted by Shahmatt Quote
Just wanted to check. Four NiMH batteries are good for at least a thousand shots. If it can run on only two it would save a little on weight and still be able to manage at least 500 shots, which is more than enough for me for several days' shooting.

So can it do that? Do we know if the batteries are connected serially or in parallel, or a combination?
I believe 4 lithium batteries are good for over a 1000 shots. NiMH, about 1/2 that.

The weight difference between 4 and 2 is only ~ 2 oz.
04-12-2010, 06:32 AM   #4
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the batteries are in series

AA cells are used because they can deliver not only the voltage but the power needed. trying to downsize you would need physically smaller cells, but always 4 in series.

In the extreme, it would be like trying to power the camera off 4 of those little button cells that used to power the TTL metering of an SLR.

I dont think so, and I see no point in trying to reduce the weight there,

If you are that limited by weight, you are using the wrong system. A little bridge camera is where you should be thinking., not an interchangeable lens SLR

04-12-2010, 07:00 AM   #5
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QuoteOriginally posted by Lowell Goudge Quote
the batteries are in series

AA cells are used because they can deliver not only the voltage but the power needed. trying to downsize you would need physically smaller cells, but always 4 in series.

In the extreme, it would be like trying to power the camera off 4 of those little button cells that used to power the TTL metering of an SLR.

I dont think so, and I see no point in trying to reduce the weight there,

If you are that limited by weight, you are using the wrong system. A little bridge camera is where you should be thinking., not an interchangeable lens SLR
I think the filler to make the 4 A76/LR44/303/307 button batteries fit in 4 AA-sized holes would weigh more than AA batteries
04-12-2010, 07:17 AM   #6
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QuoteOriginally posted by flippedgazelle Quote
The weight difference between 4 and 2 is only ~ 2 oz.
I don't think 2 oz is an insignificant weight with respect to the entire camera weight with lens.

QuoteOriginally posted by Lowell Goudge Quote
the batteries are in series

AA cells are used because they can deliver not only the voltage but the power needed. trying to downsize you would need physically smaller cells, but always 4 in series.

In the extreme, it would be like trying to power the camera off 4 of those little button cells that used to power the TTL metering of an SLR.

I dont think so, and I see no point in trying to reduce the weight there,

If you are that limited by weight, you are using the wrong system. A little bridge camera is where you should be thinking., not an interchangeable lens SLR

I am trying to piece together a system that involves the K-x in its lightest, most mobile form for everyday shooting. At present, i think the K-x with a DA 21 is a good combo. If the battery weight can be reduced that would improve the setup yeah?

Since you say the batteries are in series I guess 4.8Volts are needed to get the camera running. I guess there's no choice then.
04-12-2010, 08:01 AM   #7
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Since you are going to such lengths to save weight, why not weigh lithiums, NiMHs and Alkalines and see which ones are the lightest?
04-12-2010, 08:54 AM   #8
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Think of it this way. Will 4 car batterys start a Peterbilt on a cold winter morning? Just because the voltage is the same doesn't mean a battery has the capacity to operate the camera. If you're that concerned about weight, buy Ltd lenses and don't worry about saving an oz or 2 on batterys.

04-12-2010, 09:49 AM   #9
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QuoteOriginally posted by unixrevolution Quote
Since you are going to such lengths to save weight, why not weigh lithiums, NiMHs and Alkalines and see which ones are the lightest?
You need about 5 to 6 volts and the ability to supply over one amp of current at that voltage. If you reduce capacity, the voltage will sag more under load, so you'll get less half the number of shots from half the battery capacity (probably a lot less).

Forget alkalines. You won't get any reasonable number of shots from them. They're for emergency use only.

If you're only concerned about weight, use Lithiums. AA Energizer Ultimate Lithiums are 14.5 grams each, or 58 grams for four. This saves 50 grams (1.8 ounces) over Eneloops.

If you want rechargeable, use Eneloops. AA Eneloops weigh 27 grams (108 grams for four).

If you really, really want rechargeable and less weight, here are two things you could try. First, Sanyo make a battery called Harmolattice which is a low cost, half capacity version of the Eneloop. It only weighs 19 grams apiece (76 grams for four), so not as light as the lithiums but rechargeable. I have no idea how well the voltage would hold up, and you'd save less than an ounce over Eneloops. They might also be hard to buy. A second possibility would be to use three PowerGenix NiZn AA batteries and a spacer. Nominal 1.65 volts per cell by three = 4.95 volts. Weight is 25 grams each by three = 75 grams, plus the weight of the spacer, making total weight savings less than an ounce.
04-12-2010, 02:10 PM   #10
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I think that they used to make certain lithium type batteries that were as big as two AA batteries, I remember a few reviews on older Pentax cameras that used them.
04-12-2010, 02:56 PM   #11
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I'm really not sure, those old batteries probably won't be that good in a new dslr. However, I do remember what your talking about.
04-12-2010, 03:14 PM   #12
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QuoteOriginally posted by unixrevolution Quote
Since you are going to such lengths to save weight, why not weigh lithiums, NiMHs and Alkalines and see which ones are the lightest?
And you can peel the labels off too!

People actually worry about 2 ounces weight?
04-12-2010, 04:03 PM   #13
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QuoteOriginally posted by Ira Quote
And you can peel the labels off too!

People actually worry about 2 ounces weight?
I was just thinking... perhaps the OP is slight of frame, or suffers from tendinitis or some other malady that would make him very sensitive to weight... or maybe he simply likes to travel really light! (I do, too.)

Diff'rent strokes for diff'rent folks.
04-12-2010, 04:25 PM   #14
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Not to sound like a dick...but why do you think removing 2 AA batteries is going to save you much weight? Is that extra tenth of a pound really fatiguing you that much?
04-12-2010, 04:38 PM   #15
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I don't see the point in saving weight by eliminating 2 AA sized batteries which don't weigh much!
Even if you weigh the whole camera with the battery and without the battery, it would not be too much of a difference.
If you are feeling the weight of the DSLR, then you might be using the wrong strap.
A wide or neoprene neckstrap makes it seem to take the load off the weight of the camera.
If you just have a handgrip, then it would be a pain carrying the camera all day with just that. It would seem heavier than it actually is.
Even if you could power the camera with just 2 batteries, I don't think it would last as the current rating may not be sufficient for the given load.
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