LiON 18650 cells are also an option as they give 3.7V. Since I will connect them in parallel - and I have 10 of them already
!!! Sweet! Well you either build laptop packs or... very few people have the slightest idea what those are, and having 10? I'm guessing you're probably a CPFer. If so, what's your edc?
Mine. :b
Anyway, yes, quite so, those would make a serious battery pack. But the monitoring and charging, unless you're pulling the pack apart each time and individually charging, you'll have to design a complete liion charging circuit and either breadboard or send it to a prototype house... although the massively parallel part would work to your advantage, especially if the protection circuit is
on the cells already.
The easiest way would be to use two resistors to bias a transistor so that it's output is half the supply. Then one camera could be connected 'above' the output of the transistor and the other camera 'below' it.
No... no. A passives-only solution is the wrong approach for a battery application. Using a resistor divider would be very wasteful; you would have to allow for the maximum current or it would cause a voltage drop that would probably shut down the cameras at the worst possible time, right as they fire but before it writes the image to the card. And, when the camera(s)
weren't pulling that much current, those resistors would be nice little radiators. The losses would be the same if you used 25 pairs or two high-wattage aluminium heatsinked ones and would account for over half of the energy.
The zener method would work, just as an overvoltage clamp, but you'd have to wire up a current limiting resistor and zener for each camera tap, or every-so-many cameras... going this route I'd use a PNP assist for heavy current work, running at ~50% of rated capacity.
(and you'll still need heatsinks. Like the resistor divider approach it's not really battery friendly.)Now using a divider as V
ref for something more efficient, either a switcher or even an ldo analog regulator... but if you got to design and build circuit, why not go with a nano-picoamp voltage reference?
