I have a device I am powering using two batteries. My constraint is that I can never let the device power down. For instance, I have multiple cameras that needs to stay on 24/7 but their isn't a battery that can last that long, therefore my goal is cascade multiple batteries and be able to swap them out without powering down the device.
My current solution is to use two batteries in parallel, one with a higher voltage (Power source 2, 14V) than the other one (Power source 1, 12V). When I need to swap my main power source (Power source 2), would the second battery keep the device running?
In other words, Power source 1 should power the device during the swap. Then, when power source 2 is reconnected, it should power the device, and at the same time recharge power source 1.
Batteries I am thinking of:
Power source 1: https://www.amazon.co.uk/gp/product/B00BWW9WRM/ref=ox_sc_sfl_title_1?ie=UTF8&psc=1&smid=A17M1OH9UAKGE7
Power source 2:
https://hobbyking.com/en_us/multistar-high-capacity-4s-20000mah-multi-rotor-lipo-pack.html?___store=en_us
Best Answer
This depends on the kind of battery you are using.
If you are using lead acid batteries; this is all fine and will work the way you describe.
If you are using practically any other type of battery; you should not do this, the batteries could charge at unsafe rates. It would be safer to wire a "schottky power diode" in series with each battery so that they can both power the system but nether can charge the other. You would swap the batteries and charge them away from this system.