|Source Mod||Steve's Carts|
The time the Cart Assembler takes to manufacture carts is dependent on the complexity of the cart. For example: a cart with a wooden hull, tiny coal engine and a seat might take 3 minutes, while a cart with a reinforced hull, galgadorian drill, a solar engine, a coal engine, and all the addons/attachments may take 7 hours to finish the creation process.
Even though the Cart Assembler is balanced by the time it takes, you can't just log off for 7 hours as it needs a constant supply of coal. It can recieve coal from pipes and/or hoppers to provide enough fuel to power it. Additionally, as long as the chunk is loaded, a Stone Golem from thaumcraft can keep the cart assembler full of fuel.