Wiring shifter idea

I know that dc-dc converters used as transmissions are expensive. So I thought of an idea that works like this as a mock manual transmission to gain better high end speed without a fancy gearing system.

For example, I would have four AGM 12 volt batteries and they would be linked to a shifter that would have the voltage increase as you would shift higher. I would only use one main gear for the driveshaft 1:10 ratio to have a good amount of tourqe from the get go.

So, the “shifts” would go like this:

First shift 12 volts 400 amps
Second shift 24 volts 200 amps
Third shift 48 volts 100 amps

You get the idea, the shifter would link up the batteries in each instance as such.

This is probably a kooky idea, but there may be something here…