Logic Incorrect with creating files

Hey guys I'm having an issue with my logic in tackling this problem, I'm trying to split up files into 2000 entries per 'batch'. So once I reach 2000 ids, I create a new file (which is not listed in my code yet). But the deal is I should be able to select 8000 ids and it create 4 batch files containing 2000 ids in each.

       int idCounter = 0;
         private const int BATCH_COUNT = 2000;
                    // Incorrect logic
                    int numBatches = (idList.Count % BATCH_COUNT) + 1;

                    for (int j = 0; j < numBatches; j++)
                    {

                            _NumTotal = idList.Count;

                            for (int i = 0; i < BATCH_COUNT; i++)
                            {
                                if (idCounter == idList.Count)
                                {
                                    break;
                                }

                                idCounter++;
                            }
                      }