Sorry about necroposting but so is my life - I'm a bit behind.
I have both PRS-300 and PRS-505.
Just replaced the battery in my PRS-505.
The original battery inside is the same as in PRS-300 ("LIS1382", form factor
323450 as written on the battery itself) but the PRS-505 battery compartment is a bit roomier than that in PRS-300.
It feels as if they used the same battery for standardization purposes because for PRS-505 323450 certainly doesn't seem to be the limit.
Through trial and error I found 383454 to fit great
IF you don't reuse the metal caddy the original battery glued into. My replacement battery came from "EEMB" brand. The manufacturer lists thickness for his 383454 battery as 4.1mm (and not as 3.8 as one would expect) and the measured thickness is 4 mm. The battery fits nicely (not snugly).
The connector on the replacement battery was different from the Sony connector and I re-used the original PCM (protection circuit module) altogether with the connector.
