I recharge them the usual way, with solar panels and alternators. I usually have solar panels covering the entirety of available internal space in my vehicle. I’m honestly not sure how you’re keeping an electric car running with only 3 of them, unless it’s very small.
As for how big they are, here’s my most recent one, with six storage batteries:
It’s not enormous, but I like my vehicles like I like my PCs: Heavy as all hell for it’s size. It’s decently armed with two laser cannons, a turbolaser, and a 120mm tank cannon.
Funnily enough, the things that drain the most power consistently are the three floodlights. I swear they use more battery power than a laser cannon firing nonstop.
(Also, those reddish rams are military composite covered in gore, not spiked rams. My OCDishness would never let me mix types like that.)