A battery charging system includes a battery removably mounted on an electric power device using electric power, a charging device configured to charge the battery using renewable power which is electric power generated from renewable energy, and a server configured to communicate with the charging device. The charging device is configured to control charging of the battery accommodated in an accommodation unit on the basis of reception information received from the server. The server is configured to compare receivable power, which is the renewable power capable of being received by the charging device, with a threshold value and configured to transmit transmission information for causing the charging device to control the charging of the battery to the charging device on the basis of a result of comparing the receivable power with the threshold value.