void RegisterTokenRefresh() { var token = _netatmoClient.CredentialManager.CredentialToken; var expirationTime = token.ExpiresAt.ToDateTimeUtc(); var timeSpan = (expirationTime - DateTime.UtcNow).Add(TimeSpan.FromSeconds(-20)); _netatmoTimerToken = _timerService.RegisterTimer(timeSpan, RefreshToken, true); _netatmoTimerToken.Start(); }