I came here to ask about something like this and the price of sending it to Cown and let then "refresh" my J3 isn't right in my opinion.
I feel I should reiterate the importance of replacing the battery in the J3 only with a genuine Sony BA700 battery, not a copy battery. This is because many copy batteries have fake protection circuits, which means they can potentially explode, or, at the very least, fail quite soon. Even 'branded' copy batteries often have very dodgy quality.
You need to be careful that even if sellers say 'Sony BA700 replacement battery', they may be being deliberately ambiguous to trick you into buying a fake battery to 'replace' a Sony BA700. If you're not sure, then ask the seller and check their feedback carefully.
If you can't find a brand new genuine Sony BA700 battery, then it is definitely better to buy a secondhand genuine Sony BA700 battery rather than a brand new fake battery.
There are sellers on eBay selling secondhand genuine Sony BA700 batteries. I bought one of these genuine secondhand batteries and it works great. They're quite cheap and it's easy to buy a spare.