It's very easy to safely connect it .. Will it work properly? It's quite a spread. It would be nice if it works, but it doubt it will. All depends, A 19V brushless DC fan would likely work, A Laptop may charge the battery at greatly reduced rate or not. A TV - nope.
Best bet, get a decent quality PSW inverter in the 200-300w class, like the Morningstar suresine 300. It will run a power strip full of little gadgets at pretty good efficiency,
Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
|| Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
|| VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A
Can I safely connect a 19 volt Appliance to a 12 volt battery Bank?
100% it will not work. It will not charge the battery pack. It will not run the processor.
There are available 19V power supplies for computers, etc. that are designed to run off a nominal 12V car electrical system or in some cases also an airplane system.
More efficient than running an inverter to get 120V AC and then converting down to 19V with a standard brick, but perhaps more expensive.
Is 19 volt a minimum for these household items? Can that run off of 24 volt Bank ?
The 19V figure is based on the battery voltage used inside the appliances.
You use a higher battery voltage than 12V because that is a better way, from an engineering viewpoint , to pack the power in than to try to use fewer higher capacity cells at a lower voltage.
And since the primary use is from 120V AC power there is no balancing push to try to get them to operate from a 12V DC source.
One of the problems is that a nominal 12V DC automotive system will actually range from as low as 10V to as high as 15 volts. That means, effectively, that the internal battery would have to be 10V or lower.
Basically it is very unlikely to happen.
Looking at the other side, a nominal 19V system will get a highly regulated input because there will be a converter of some sort from 100-140 AC to 19V or 10-16 V DC to 19V.
There is absolutely no reason for the system designers to build a nominal 19V system in a way to operate safely on a DC input of 20-30V DC in addition.
Also very unlikely to happen.
You could, however, build a relatively inexpensive DC to DC converter or series regulator to drop the 24V to 19V before feeding it to the appliance.