1W Christmas LED to be powered by 18650

[loooord]

Please help me out here,

I have tried to put up some Christmas led to windows where we do not have any electrical sockets. The Christmas light is only rated around 1 Watt and it has been powered by a transformer with 3V and 330mA which is 1W

Can one 18650 battery only operate this Christmas LED for 10,5 hours? I think the battery is Samsung and has 2500mAh.

2500mah x 4,2 V / 1000 = 10,5 Wh

What a crappy battery this 18650 or do I calculate wrongly this?

Second question is, do i need a led driver to do this?

br. jan

 

[Changchung]

I am pretty sure that you can use a single 18650 but I will recomend you use a protected to avoid low discharge the battery

 

[poguy]

You need to see if the LED light has its own constant current regulator. If it does you just hook up the battery and it works. Cheap lights use a series resistor and that reduces efficiency, not a big factor with an AC supply.

And the LED's may not draw a whole watt. The power supply is probably some off the shelf item that is good enough. Best bet is measuring current draw and going from there.