November 2014
I have the following three Nikon cameras: D3200, D5100, and D5300 that I want to use in my black bear wildlife research work. There are no electrical outlets to recharge the small lithium-ion batteries that come with the cameras in the desolate areas that I frequent. A car inverter to a regular lithium charger is out of the question because four-wheel drives can't get back to the remote areas that are accessible only by horse and by
packing on foot.
Furthermore, the cameras need to be in the "on" mode for several days at a time and left unattended in cave areas, where continually re-entering the caves would not be particularly safe were I to repeatedly reinstall the little batteries. There is some flash power being consumed as well with every exposure, so the batteries drain fairly rapidly.
I would like to run a bipolar cable from a couple of parallel connected 12 volt/18 amp-hour batteries into a drilled hole in the camera battery snap cover in the camera base. That probably will probably require cutting open and possibly destroying a battery pack and removing the lithium-ion cells so as to connect the voltage dropped wires to the battery terminals inside the battery pack which, in turn, will make contact with the camera's internal fixed contacts.
Can you please assist me with a "camera safe" regulated circuit to drop the 12 volt gell cells to a constant regulated output level for a Nikon EN-EL14 lithium-ion battery which is rated at 7.4 volts at 1,050 mAh (7.8 Wh)? The Nikon MH-24 battery charger that comes with the cameras has a charger output of 8.4 volts at 0.9 amps and charges each EN-EL14 in about 2.5 hours. I would greatly appreciate your help and advice with a voltage dropping circuit and battery disassembly details, or if disassembly is not required, how to proceed with the hook-up.
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I want to offer some facts that may help you form your own solution.
1 - 7.4 volts happens to be 2X of 3.7 volts, and 3.7 volts happens to be the exact rating of most all cell phone batteries. Cell phone batteries can be bought very cheaply via the internet.
2 - The next fact is that the battery door on Nikon cameras can be removed. Open it to approx 45 degrees and gently twist it out.
3 - The next fact I would share is that a battery grip is a way to attach, usually two batteries, to the bottom of your camera. Some of the grips come with interval timers for timed exposures, they are all made in China, and as such, eBay is full of second party battery grips for many popular cameras. The grip might be the better way to modify your cameras without damaging them.
If you were to use cell phone batteries to make your own battery pack, your next challenge would be to build a charger for them, since charging them one by one would be labor intensive. Making a battery pack of the cell batteries would require them to all be the same rated capacity. Connect them in series, in pairs, to bring them up to 7.4 volts and parallel as many as you like to increase capacity to meet your requirements.
Lastly, NEVER attempt to open a battery, especially a Lithium battery. If you were to expose the Lithium to air, it most likely will explode and seriously injure you or result in your death.
