can i power my torch with usb?

Hi so in theory it should work however a 6 volt bulb is going to be dim with only 5 volts across it's element.

The batteries and plugs will cost you more than a whole new torch that is built rechargeable and has LED's.

You can always try it and see what happens.

It should - either one, as long as the power bank can supply the current necessary to run the torch. 6V usually means 4 cells @ 1.5V nominal each. Under load and after a few minutes of runtime, even alklines will go down to ~1.3 Volts actual, not that far from the 1.24 Volts you would get from rechargeables, which in either case would add up to the the ~5 Volts you get from a power bank.

The problem would be the current. A 4D Mag will probably draw at least 1 Amp, maybe 2.5. You'd need a hefty power bank to supply that. Other 4D lights may draw even more power.

this will depend on the make and model of the torch. I have one that doubles as a signal beacon a power bank and is verry useful

Trial and error is the best way to find out here!!

You just use rechargeable batteries in place of the regular ones!

yeah