We really wanted this week’s Fail to work. [Michael] wanted more juice for his Nikon D3100 camera. The idea he had was to replace the cells of the battery with a Buck converter and add leads for an external battery. This opens up the possibility of running from a wide range of voltage sources; an attractive prospect for devices using specialize batteries. Specifically, he wanted to swap out the stock 7.4V 1030 mAh battery and use an 18 Ah lead acid one instead.
The biggest hurdle to get over in a project like this one is the logic the camera uses to communicate with the battery. For this reason — and for the ease of hitting the right form factor — he scrapped an old battery pack to reuse the logic board and enclosure. His power supply is a free-formed circuit which fits nicely in the allotted space.
The circuit powers up, but only to about 6.4V. This isn’t enough to run the camera, which means this was just an expensive way for [Michael] to practice his soldering. After the jump you can read his recounting of the experience. You’ll also find a few of the build images, and the two hand-drawn schematics he used during development. His Dropbox has the entire collection of images.