Some more anecdotal evidence of the 1800mah mugen battery for the N810. I bought one from MugenBattery.com. It was on backordered. Fulfilled a few days later in February 2010. I received it and have been using it for a month. What a dramatic difference from my original battery. Mostly because that original was done for. Now I have regular 5 days of standby and 5-6 hours of regular use. Very effective. I thought it was worth the money. But YMMV.