I just made a power supply so I can run my E-M5 from a 12V batter (e.g., jump start battery, car, etc.) without a $200+ dollar battery grip. I'm not into reinventing the wheel, so got ideas from others and took it from there. I've included sources so you can see who the smart folks are who came up with the original approaches. This is geared to the E-M5, but it will work for any camera. All you have to do is put the right connector on the end of the supply so it mates with your device. The basic approach comes from this link where the DIY project results in an AC adapter. Basically, you make a mock battery that you insert into the camera. You have to leave the battery compartment open, but for tripod shooting, that should be a minor issue. I do astrophotography/star trail shooting so need power out in the field which why I made the supply. The linked page is in Polish, but Google translate will fix that for you. See bottom of the link page for You Tube video of device in action. Radom na fotografii - Zasilacz sieciowy do aparatu Olympus OM-D EM-5 I don't really need an AC adapter at the moment, but do need a long term battery source for doing my star trails and other astrophotography shots. So instead of an AC adapter, I made a variable regulated power supply that provides the right output voltage (8-8.5V for the E-M5) when plugged into a 12V power source. I initially made the power supply for my Pentax DSLR that coincidentally has the same input power requirement so all I had to do was replace the Pentax jack with an Oly "battery". I bought a cheap $10 BLN-1 battery, removed the cells and wired the power supply to the correct terminals. Now I can just plug the power supply "battery" into my E-M5 and power it all night long if I want to while out in the field. The following link is to a file that originated as a blog post that shows how to make the power supply. It's for the Pentax K-5, but as I said, just replace the Pentax jack with an Oly "battery" and you'll be good to go. The blog seems to have died, so I PDFd my copy of the project and posted it here: https://dl.dropboxusercontent.com/u/10452497/DIY%20Power%20Supply.pdf Here's a link to a source for the regulated power supply: 3A Adjustable step down switching voltage regulator For the camera power supply, I used a small project box from Radio Shack. However, I used the power supply plans to make a unit for one of my telescope mounts. For that, I just housed the power supply in a piece of 1" PVC pipe with rounded end caps. I drilled through the end caps to pass the wires through each end, strain relieved the wires inside and out with mini-cable ties, and used silicone aquarium sealant to seal the holes. The casing is only about 6" long and is quite water resistant. I wouldn't leave it out in the rain, but the end caps are tight enough that I have no worry with it lying in dewy grass. One final mod I am going to make is to make the Oly "battery" portion of the camera power supply detachable as the plans advise (I made it last night and didn't have a plug/jack set on hand). Besides providing protection from the cord being stepped on/yanked while in the camera, it will allow me to make an AC power supply in the future (if I decide I need one) without having to make another "battery". Hope this is useful to folks.