Question about battery

Hey, I have a minimoto and I would be willing to add some LEDS to it... something like 20-30, so here comes my question, which battery should I use to wire them to?? It should be something small, rechargable and easy to find i guess... I though on a mobile battery since I got some spare ones of old mobiles, I took a look at one of them and I could read "720 mAH / 3.7 V", so I really dunno if this battery would be ok or not, I would like to fit some regular 3mm/5mm high bright leds or whatever they are called sorry :/ .. Suggestions are welcome aswell, thx in advance,
Cheers /ubbthreads/images/graemlins/help.gif

Use a 12v sealed lead acid battery and wire the LEDs in sets of 3 in series. Use a resistor if necessary. 20 5mm LEDs would draw about 400ma in a parallel at about 3.5v but in a 3 series you could wire 30 leds to a 12v cell and it would draw about 200ma. Runtime may be an issue on large numbers of LEDs so calculate the mah and choose battery size accordingly. Also recharge time may be an issue, longer runtime would help with slower charging rates.

You could use your 720mah battery, it may require dropping resistors when freshly charged. If you ran about 18-20 5mm LEDs at 20ma it would last close to 2 hours off a charge I figure. 36 LEDs would drop it to less than an hour.

It all comes down to how much light you need, the more LEDs or higher output LEDs you use the brighter light you will get.