Just got back from ROTOR QUEST in Toronto this aft. Picked up a pair of TATTU 1800mah lipos which measure 3.5"x1.8"x1". I bought them to replace a pair of 1800mah ElectricFly with same dimensions, they puffed and went bad fast soon after.
I expect to get over 8 minutes flight which is what the ElectricFly ones got. These TATTU are only a little heavier than 1300mah ones and maybe 1.5cm longer Mine came in at 146gr after some wire shortening, the 1300mah's I got down to 116gr, a basic >< 5% increase in all up weight. The mah is good and the battery could be reshaped to become slightly shorter while taller and be nearly identical in dimensions to a 1300mah one.
The TATU lipo is slightly larger, weighs little more than a 1300mah one and should balance a 300 the way my ElectricFly 1800mah lipos did a year ago. My habit of placing my 1300mah lipos about an inch forward of the normal placement got my 300 balanced well but I felt the larger 1800 was better in size weight and flight time, should be about 30% longer flights times, that's what I found when I was video'ing my 300 last year using both 1300 and 1800mah lipos (separately of course).
Fun stuff, I'm looking forward to running these 1800mah lipos for extended flight time.
take care and fly well.