In fact you can make the Ipoo battery fit your H340 as well the H320 but you must remove the blue rubber between the hard-drive and the battery, (it's what I done) or cut some part of the the folded aluminum on the side like said in the previous posts. (Swifty and me)
At the opposite of waht you said you should use the
IONITY LiP385583 for the H3x0 at www.dapstore.com. This battery have the good polarity on the molex connector (it's not the case of the Ipoo's one) and fit in the H300 series. The price is higher but you are sure of the compatibility...