External LED power source

[ZallCaTor]

I plan to use an external battery instead of the DS's battery to power a multitude of LEDs and a cooling fan (for effect, cuz Murica) 
I want to use a USB rechargeable lithium ion battery pack.

My question is, what LEDs work best with a 3.7 V battery and does the mAh of the battery have any effect on what LED I should use?
I'm not very learned in electronics, and usually end up popping my LEDs when I hook them up, so any knowledge you have on this would be very helpful.

[WHITE 4ND N3RDY]

The mah of a battery is just how long it will run till it runs out of juice. I think ( not 100% positive ) if I have a 2000 mah battery that means u will get about 10 hours out of it. Simpleist thing to do is just Google mah and there be some sort of chart that can explain how much life u can get out of a charged battery basses on its mah.

As for your leds all color spectrums should work ok with 3.7 v as long as your using 0603 or 0805 smd leds. Though red and green yield the best results. Other colors like white, blue (especially purple) will not work as well and will dim out when the battery is dying. If u plan on using 3mm or 5 mm leds u will have to figure out what voltage is needed for them and may have to use resistors to regulate voltage flowing through the led. Hope this helps. Not a tech guy myself lol. Again though Google is your best friend and there's all sorts of votage calculators for what resistors u will need based on your application.

[ZallCaTor]

Yes, thank you. This helps me a ton!