Battery issues on Fairphone 2: time for a new battery or can we fix it?

Issues charging on Fairphone on both AC and from computer starting from last month.

First I noticed that it would take ages to charge on USB from a computer. In the past few days began to have trouble reaching maximum charge, and was only able to reach half charge yesterday (see battery history graph below).

Have cleaned the connectors on the battery using alcohol.

Any other suggestions?

A post was merged into an existing topic: FP2 Battery Problems (drains quickly, CPU gets hot) - See batteryguide for workarounds