I ordered an LED light that ships without a power supply and has an USB connector to connect one. I thought I'd just buy some power bank subsequently to power the device, but then I realized that
all the power banks on the market can only provide like 1-max2.4 amps. Why can't one find a single one above this limit? The funny thing is that even power banks having 6-8 pieces of 18650 cells are limited to 1-2 amps and I just don't understand why as the C-rate of some 18560 batteries can be so high that some of them could output 10 or even 20 amps, not to mention if you bind 6 or 8 of them together.
Now it's a pity a cannot buy a good quality power bank to drive my lamp and I have to buy some Chinese 18650 battery pack which I don't know how reliable is (and by far less practical for other purposes).. Oh wait, I have a USB connector, so that's not an option either :/
Best Answer
What brhans said is valid IF the lamp is in fact intended for "USB 5 Volt" input but it almost certainly isn't.
Use of a USB connector does not mean it is "USB 5V" operational.
If it was then you MAY be able to parallel connect multiple outlets from some hi power [tm] units. Or not :-).
HOWEVER: the lamp shown says
"...Power Source: 4 x 18650 battery pack (Not Include)..."
Looking at other similar and possibly identical lights such as this one shows most specify 4 x 18650 cells arranged 2S2P.
You need a spec sheet for the light.
Whether you can get one is TBD.
Cree XML2 flux binning here.
See page 3 for T6. and
XML2 data sheet here
Max current per LED is 3A
For the max flux T6 = cool white
Minimum flux at 3A and about 3.3 Volt ~= 1000 lumen.
So the whole lamp will produce about 3000 lumen maximum at 9A. A V_LED ~= 3.3V at 3A and you need some headroom for wiring, regulator etc, you cannot run one at full current on a 1A LiIon cell. You need 2 x LiIon and (hopefully) an efficient buck-regulator.
9A LED current will require about 5A from 2 x 18650 LiIon cells with a decent buck converter. Needless to say, this is 'rather more' in voltage and current than you will get from any "USB power bank".