I am not sure your problem settings. In general, batch is used for both input and target data.
If you want to use 1 day’s data to predict another day’s data, then batch_size can be 4 (or any number that fits your memory). In the situation, the number of target data samples will be 4 in a batch too.
If you want to use several days’ data (say 4 days) to predict another day’s data, then 4 is not your batch size. The input 4 days’ data constitutes one training sample.
Best,