Couldn't figure out where else to post this. Very happily using the 510 (wife and I) for 5 days,but I already realize the batt is not going to cut it for me in the long term. I'm trying to understand the eGo but no retailer pages really explain this stuff. I have been using rocky mountain vapor and they have the eGo batt for $20, and the charger ($10) is out of stock and has been all week. I've checked many other pages and it seems like there are different mah (600-900), and and other models too, they only sell the batt not the chargers, etc, etc. I want to keep using the same attys and carts, from what I understand, I can? I'll keep my 501 batt for backup and let my wife have the other two 501 batts and I got her a pcc. Do I just need a ego batt and the correct charger? It seems the 501 chargers will not work with the ego? Any idea where I can find both right now, cause I'm going a little crazy trying to find this combo with out buying an entire starter for $75