Hi guys I recently took the plunge and got a "1800mah" + battery charger battery from Ebay. I was prepared for the worst in case, ie getting a cheap Chinese re-branded 900mah battery. But was presently surprised. I got the battery here: HTC EVO 4G BATTERY 1800+Dock USB CHGR DROID INCREDIBLE - eBay (item 220674019393 end time Nov-23-10 15:11:41 PST) I gamble on the seller(chichitec), since he/she have a 99.7% positive rating with many active listings. So if I did get ripped off, i can threaten the seller with bad reviews to have him refund me the cost + shipping. I got the battery 2 week ago, and been doing some testing with the battery. Here is my stock battery usage: -My daily usage: 12-13 hour cell standby, with barely 3 hour active use (mostly playing psx4droid after work) will cause a auto shut off on my stock battery -I got the phone back in June 5, 2010 and have been a heavy user. I charge the phone every night, but atleast 2-3 time a week i would use the phone till it power off on it's own (mostly playing games). -Going off xda forum's battery testing, the stock evo battery usually have a capacity around 1435mah new, and capacity decrease about 1.5% per month due to usage. - So 1435 * 5 month usage ~= 1320 mah for my stock battery current capacity. Here is my extended battery usage comparison: -Past 2 week daily usage: 12-13 hour cell standby (for my phone usually 10hour stand by is same as 1 hour active use), with slightly beyond 4 hour active use (range from 4hour to 4h 15 minutes). -Going off above math the new battery have about 18% to 20% capacity above my current stock battery. -1320 * 1.18 (conservative estimate) = 1557mah. -So far for the last 2 week, the battery capacity has been pretty consistent. I didn't notice any noticeable decrease capacity in the 2 week usage. -The extend battery charges in the phone without any problem (no excess heat, won't refuse to charge, etc) About the external charge: -Charge the "extended" battery in 5 hour. -Also charge the stock Evo battery to full in 3 hour. So for $29.99 + $5 shipping (I offered $25 + shipping and was accepted by the seller). I got a battery that seem to have close to 1550mah (most likely 1500mah) battery capacity. While it is not as high as 1800mah that I had hope, for the price I think it is a pretty good deal. So I want to let other Evo owner know about my experience. If you want a quality backup battery, or want slightly more juice then your current stock battery (especially if you had the phone for a while now like me). You might want to check into this. PS. I know about the 3500mah battery, but I think the EVO is already thick enough, i can't imagine currying something thicker.