[QUOTE] the ability to hot swap a low or dead battery[/QUOTE] Some of my Japanese electronic pianos now use a 1 Farad, 5V memory capacitor, instead of a memory battery that goes dead in a few years and requires me to replace them. Every time you plug the piano into the wall, it recharges this monster cap, which about the size of a button battery these days, almost instantly, ready for another month of no power and not lose anything. I've been dreaming of finding how to mount a couple of these in parallel into the Nokia tablet as a "backup battery" for just that 10 seconds it takes to pop out the dead battery and pop in a charged one....WHILE THE TABLET WAS BOOTED...not losing anything. This technology may be just around the corner replacing the whole chemical battery scheme all together with a powerful, ceramic, SUPERcapacitor. Zenn electric cars of Canada has a deal to use these massively powerful capacitors, that are quite tiny and light in comparison with current battery technology, TO DRIVE THEIR ELECTRIC CARS hundreds of miles at 70 MPH! Google EEStor and have a look around. If this technology happens, they may have just eliminated the biggest stumbling block, batteries, to electric anything! Capacitors can charge as fast as you can provide power to them, unlike chemical batteries which take time to charge and are inefficient. Of course, you'll need 3-phase 908V at 200A service to recharge your nice electric car in 30 seconds....or less. Kilowatt Hours stored in EEStor still have to come from somewhere. The faster you recharge, the more instant power you'll have to provide to recharge it. Imagine your portable electronic devices you plug into a charger that uses as much power, in a few seconds, as your electric stove. Capacitors charge without getting warm....a sign of great storage efficiency. The only loss is a series resistance, easily overcome by slowing down the charging to a few minutes instead of a few microseconds at 5000A.' The car, by the way, will run 250 miles at 80 MPH and the massive charger will be limited only by your source power line amps, around 2 hours to fully recharge, dimming the lights in the neighborhood in the process...(c; The lights in the den might blink recharging your sellphone from the 240VAC 50A load for 8 seconds....