To add batches to the products while converting purchase orders into purchases on android please follow the below mentioned steps:
Step 1: Add product with batch.
Please refer to below mentioned article.
Step 2: Create purchase order by adding batch item.
Please refer below mentioned article.
Step 3: Now select the created purchase order and click on the three dots shown.
Step 4: Click on Convert.
Step 5: Click on Convert to Purchase.
Step 6: Click on the added batch product.
Step 7: Here try stocking out or change quantity of the product added by clicking on - symbol.
Step 8: Different batches of products will appear, add the desired batch of products by clicking on + symbol and click on Continue.
Step 9: Click on Continue.
Step 10: Click on Create.