Heya -- does anybody know whether there is such a thing as a rechargable 9V power source that can be hooked into a 28V circuit for application on a plane?
The long story is like this: I have a couple pieces of equipment (most notably a tricked-out non-standard GPS) on a plane that run off those little 9V bricks. The batteries are good for about a week, then they need to be exchanged - which is kinda annoying. There's a power-supply (run-off-the-mill wall-wart) that I run off a little 110V inverter circuit that'll supply power while the plane is actually running, so the batteries won't poop out during flight - but that has power only while the engines are running (say 5hours or so per day during flying season). Now the problem with changing batteries is that the system loses configuration when I do it and I have to go set it up when it comes back on (just a few minutes, but it's annoying).
So I figured there must be some kind of gizmo that'll accept either 9V regulated or (better) 28V unregulated on the input side when available while recharging some kind of battery; and supplies 9VDC on the output side whether the input-side is powered or not. It's not a whole lot of current (think two or three 9V batteries lasting for a week or so) and I'd be happy if it just pooped out after a week of sitting unpowered - but I'd like to have the 9V available continuously as long as there's daily (or, say, every-other-day) a couple hours worth of input. The problem is that I have no idea where I'd start looking for that kind of thing. Boating folks typically run off the boat-batteries which are available 24/7, not "when the engines are running".
Anybody have an idea?