You can have 16 total, more in comments

16 batteries!? i have beat the game and still only have 3!

Literally cole mcgrath

What happens after blue though

The refineries let you buy any zonai device you've already obtained after you get to full blue

So, first the math

1 crystalized charge is 3 zonaite

100 crystalized charges is one energy well, meaning you need 300 zonaite

So 900 for one full battery icon.

To upgrade from 1 to 8 you need 6,300

But I just finished doing that.

So, to upgrade further than that to get to 16 you'll need 7,200 zonaite (this is going from 8 to 16)

However to upgrade all the way to 16 from 1 battery 13,500 zonaite

So yeah, you'll need to do a lot more mining.

When you start upgrading past 8 your batteries will start turning blue