What is a suggested portable power source for 100w Arduino project?
Since 90W at 5V equates to 18A you should consider splitting your strip into segments and powering each one separately from its own switching voltage regulator.

By doing so you reduce the current requirements from your power source proportionally with the increase in the supply voltage.  For instance, if you increase your supply to 12V you roughly halve your current requirements from the supply, which means smaller cables are needed, and less stress is placed on any batteries (current draw = heat generation - the more current you pull from batteries the hotter they get. Batteries that are happy supplying 18A are necessarily bigger and higher capacity than those that are happy supplying 10A).

As an example, you may consider something like this:







simulate this circuit &ndash; Schematic created using CircuitLab

That shows just two sections, but you would want to split into more than that (ideally).  Each regulator has to provide enough current for that segment of the strip with a little extra overhead. 2A and 3A switching regulators are common and cheap under the description of "UBEC" for model vehicle operation. Assuming 2A regulators you could have 10 strip segments (20A total capacity). At 3A you could have 6 segments (18A total capacity), etc.

A suitable battery arrangement would be "3S" Lithium Ion batteries (three cells in series, nominal 11.4V) for ~10A draw, or "4S" (four cells in series, nominal 15.2V) for ~8A current draw.

Of course, the rated wattage of these strips is for every LED set to white at full brightness. If you are only going to have less LEDs on than that you could get away with a smaller current supply, though you risk over-stressing it if you ever do then have more LEDs on.