Newbie question

Hi! All: newbie here. Have a question hope to get some help:
So I understand if you connect two 2000mAh battery in parallel, you get the same voltage but double the capacity, essentially one 4000mAh battery.
What if you connect a 1000mAh battery with a 3000mAh battery in parallel? Do you still get 4000mAh in the end? What's going to happen when you put a load on it? is the 1000mAh going to produce less power while the 3000mAh produce more so eventually they die together? Or are they going to produce same rate of power but the 1000mAh will die ealier? What happen after that?

Thanks!

Have you gone through the FAQ? It's located in the top section of the main page.

Yes, capacity is added together in parallel, regardless of the differences of the capacities. The 4000 will drain 3x faster than the 1000. They will essentially be empty at the same time. Just as if you had a 100 gallon tank and 10 gallon tank connected together, then drain from the common spout. They will empty at the same time.

Got it. Thanks for the explanation!