Re: iphone 5 battery
The iPad is compatible with the iPhone 5W charger. It will charge perfectly fine, it will just do so much more slowly (at most 1/2 the speed.) An iPad uses up to 2 amps and the iPhone charger is 1 Amp.
The iPhone and iPad will work with any and all USB chargers but unless it's a charger intended for Apple devices (be it genuine Apple or 3rd party) it may all back to using the USB standard of only 1/2 an amp (2.5 watts.) This is especially the case with Android adapters.
Again, your iPhone and iPad will charge, just slower. The iPhone uses up to 1 amp to rapid charge so 1/2 an amp would take twice as long.
Raivo said it was 24V adapter? USB is 5V. So if it's really 24V then it could fry the iPhone. Incidentally if the voltage is less than 4.5 or greater than 5.5 V the iPhone and iPad will not charge at all, it will block the charging circuitry and hopefully won't be overloaded. But if he meant 2.4 W (watt) or 12 W (watt), then assuming it's a standard 5 V USB adapter, the wattage won't matter. The iPhone and iPad can use any wattage 5 V USB adapter but may use only 2.5 watts (the USB spec.)