I have three Nikon D300 bodies with power grips and wanting to get some use out of them for some game cameras on my property to get some critter shots. I am wanting to rig something up to power them for a say a week. I notice with the grip and two batteries, they work for a 2 days in standby and I have the AC power adapter but cant always have power in the field. I searched the web several times and really trying to find a way to power these in cold conditions for a week at a time. IE a dummy battery to mount using one of the large F Sony batteries etc. Again I have the dummy battery to the plug for ac. Anyone have any luck with this, The web has lots of El-15a set ups but none for the D300. Thanks.