private function refreshToken()
    {

        // Make the post request for a new access_token
        $response = $this->httpRequest('post',
            $this->sso_base . '/token/?grant_type=refresh_token&refresh_token=' .
            $this->authentication->refresh_token, [
                'Authorization' => 'Basic ' . base64_encode(
                        $this->authentication->client_id . ':' . $this->authentication->secret),
            ]
        );

        // Get the current EsiAuth container
        $authentication = $this->getAuthentication();

        // Set the new authentication values from the request
        $authentication->access_token = $response->access_token;
        $authentication->refresh_token = $response->refresh_token;
        $authentication->token_expires = carbon('now')
            ->addSeconds($response->expires_in);

        // ... and update the container
        $this->setAuthentication($authentication);
    }