I am not an expert but that won't work. LEDs aren't quite like the old type of globe.

They really need the exact amount of current and voltage. Also there are different brightness levels based on the quality.

Looking at that LED it won't work. 2 x AA batteries will put out 3 volts max. The globe you are looking at requires 3.3 volts. You either need more battery power or you need to look for one that is under 3 volts. Also if it is less than three volts, you will need a resistor to drop the voltage from three to what is required.
If you look at the LED in the link, it says down the bottom of the description that if you have a certain voltage, what size resistor to use. You also need to make sure you wire the positive and negative correctly to the LED.

Without knowing how much space you have in your custom, another option could be the button batteries. I just got an oversized KO MP-12 Sideswipe that the headlights work on. It has three AG4 thick button batteries (not the largest size ones) that power the headlights. They would be putting out 4.5v but take up bugger all space.

So in summary, lower your lumens or increase your voltage and add a resistor.

Have a look at the two links below. One of them has someone with a similar problem. The other may explain things better than I.

Hope this helps.


http://www.techdose.com/electronics/...109/page1.html

http://ask.metafilter.com/98974/Why-...D-angst-inside