Choosing a battery

I'm building a segway, but am not sure what batteries to go with? I need about 15AH, 24V. I've been thinking motorcycle batteries, but I'm worried about discharging them completely. This guy (**broken link removed**) just used a bunch of 6V battery packs together. What should I go for?

For weight/capacity you can't beat lithium batteries, but you need decent charge/discharge control circuitry.

How are lithium batteries sold? Sorry I dont work with batteries or RC stuff much - are they sold in one big "unit" or are they sold in 6V battery packs / single batteries?

One place to get hobby sized packs is FMA direct, but it's gonna get expensive fast depending on what your voltage/current and capacity needs end up being. You can get both individual cells and packs. I'm sure you can find a better price (by at least 50%) if you hunt around for a site that resells large capacity packs. FMA is aimed squarely at the RC hobby field.

**broken link removed**

Simple lead acid batteries will work, but will be much larger and much heavier.