I got a new camera, a Pentax KX, and am enjoying the movie mode, which not surprisingly eats batteries at a rate of about 1 alkaline AA per minute!

Can you point to any examples on the web of people building a circuit to patch some large rechargeable battery (say my laptops Li-Ion) to an AA battery compartment?

  • \$\begingroup\$ This seems to be more of a consumer electronics question then a design question, what do others think? \$\endgroup\$
    – Kortuk
    May 18, 2011 at 19:14
  • \$\begingroup\$ @kortuk The amount of design work is more centered around the mechanical aspects instead of the electrical ones. \$\endgroup\$
    – Kellenjb
    May 18, 2011 at 19:47
  • \$\begingroup\$ I think it's okay and someone answered with exactly what he was looking for. The question isn't obnoxious and is more than slightly electronics-centered. I'd leave it. \$\endgroup\$
    – AngryEE
    May 18, 2011 at 20:43
  • \$\begingroup\$ @AngryEE, I think it is right at the boundary and just was looking for input. I currently hold no intention of removing it. \$\endgroup\$
    – Kortuk
    May 19, 2011 at 0:20
  • \$\begingroup\$ I have no experience with Pentax products but it seems that that battery usage rate is far too high. I'd check usage with other Pentax owners and also look at the brand of Alkaline batteries being used. \$\endgroup\$
    – Russell McMahon
    Nov 10, 2012 at 5:27

2 Answers 2


What you want to do is create a "dummy battery" that will fit inside the camera in place of the AA batteries and make contact with the battery contacts in that compartment. Here's an example of someone doing something similar: http://www.lumika.org/gear_a2e_batts.htm.

Building the dummy battery for your camera is really just a mechanical issue. The electronics design part could come in if you were trying to supply power with a higher voltage and needed to regulate it down to match the voltage output from the AA batteries (most likely this is 3 V for the two AA batteries in series). This will depend on your camera and the external power source you decide to use.


Your K-x supports a AC adapter plug. Find the appropriate plug, wire it up to any proper DC voltage (check the K-AC84 accessory to see what voltage it runs at) battery you like and go nuts.

  • 2
    \$\begingroup\$ As an aside - you may want to pop over to photo.stackexchange.com and ask if that battery usage rate is normal or if using a different battery may be better. We have several prominent Pentax members. \$\endgroup\$
    – rfusca
    May 18, 2011 at 22:58

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