What a battery!, page-56

Completely possible, completely practical. All that you need is to make sure you have appropriate battery management systems to handle the charging, energy transfers, and discharge in an appropriate way. (As well as appropriate mitigations for the risks of the various chemistries - eg, lithium fires.)

There is nothing in electricity that demands that storage be uniform. I've been told of one application where they used banks of supercapacitors to capture energy bursts and feed them into the battery in a more controlled manner. It's all down to making sure that the charge and discharge of each bank of storage is managed at an appropriate rate, and being prepared for the times when a given set of storage needs to discharge for maintenance. It's a hard problem to solve in the general case, but with a few basic assumptions that will hold in most circumstances, it's very tractable.

(I'm using the term "hard problem" in the computer science sense, meaning that solving it completely, for all edge cases, in a satisfactory way would require more computational power than we have available to us. Broadly speaking. Handwave, handwave.)