I am thinking about purchasing and/or assembling a cheap external dc power supply for my DSLR camera. I have been reading a number of articles on this topic including this one: http://www.diyphotography.net/how-to-make-a-dslr-battery-run-4-times-longer I have found that the technical level is somewhat high for me. I am very poor at soldering and taking things apart and putting them back together. I am considering purchasing this ready made item from Ebay http://www.ebay.ca/itm/180659453326?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649 which I hope will provide a safe external AC power supply. I am hoping to modify this device such that I can also use the dummy battery as a connector for a portable DC power supply. I intend to simply cut off the adapter and use the dummy battery as a ready-made connector and simply connect a cigarette lighter adapter to the wires to plug my camera into my 12vdc to 120vac inverter via the 12-volt receptacle in the inverter. It is sold by Canadian Tire similar to this http://www.canadiantire.ca/AST/brow.../Eliminator+600A+400W+Power+Box.jsp?locale=en except that it is 300amp/300watt instead of 600/400. It produces square ac waves but I presume this is irrelevant. I will simply be drawing on the small 12-volt battery inside it. I propose using a simple buck step down inverter such as this one: http://www.ebay.ca/itm/331021547239?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649 The output is rated at 7.5 volts and the camera batteries are rated 7.4 volts so I'm assuming that will be close enough. Any comments on any problems I may encounter would be appreciated. Mainly, I want to be sure I do not fry my Canon T2i camera. Thanks in advance for any comments.