You're outside the Newbie Tank here so you should be careful about what you ask or you're going to get flamed as you have a couple of times already in this thread.
Everyone says the stock Kraken battery is junk but I haven't had any trouble with mine, it has always lasted a full game day which is usually four to five hours. I would highly recomend a good smart charger though as the cheap wall chargers that come with the Kraken will ruin batteries. Getting replacement batteries for the Kraken is a bit of a challenge as serveral people have already stated. The battery is a smallish large type with small tamiya connectors. You can make or buy adapters to allow you to hook regular large types up to it easily enough but watch out for the size, regular large types are usually a fair bit bigger and have trouble fitting into the stock.
Edit: Also, in terms of battery voltage, I wouldn't advise anything other then an 8.4 with the stock internals. Anything higher, like the above suggested 9.6, will wear out the stock internals fairly quickly.
Last edited by Kuro_Neko; December 22nd, 2008 at 22:24..