sej7278 wrote:this looks like it has a nice 6000mAh for 99p: http://www.ebay.co.uk/itm/281626121177 (edit: terrible reviews, more like 1500mAh)
There are no 6000mAh 18650 batteries. Anything above 3400mAh and anything sold as "Ultrafire"/"Trustfire" is usually fake and doesn't even come close to the advertised capacity. If you are looking to buy 18650 batteries: this guy has run some really extensive tests http://lygte-info.dk/review/batteries20 ... %20UK.html
However I don't think 18650's are the best choice here. They are fine if you have some salvaged ones from a dead laptop or power tool battery (dead packs usually only have 1 or 2 defective cells). If you are looking to buy new batteries anyway, I would recommend using cell phone batteries: they are cheap, readily available and much thinner than 18650's.