Prius Auxillary Battery Size

Yes. But admittedly not much.
If you have access to power where you park, a battery tender and block heater will be a much better investment.

Oh......and you don't KNOW if anybody has damaged their car trying your "modification" because most people would be embarrassed to admit it.

 

For myself, I solved this issue. He refused a lead battery, LTO is not afraid of frost.
You have no idea what these cars are capable of, the diode is a very simple way.

 

I have been an Electronics Engineering Technician for a bit over 50 years.
I KNOW how things work. And have seen many "very simple" things go up in smoke.
Stay warm.

P.S. Who would not accept a lead battery ? And what is LTO ??

 

This battery should still be under a full replacement warranty for some time.

 

Lol, not often... That's why I have you on "ignore" so I don't see your posts, as well as posts of a bunch of others, unless I click to view the whole thread. Seriously Sam, anyone who shares something smart and clever we've not learned about yet the first thing you always do is tell the person they're wrong before you even learn more about it. It comes across as close-minded and rude... Why can't you be more friendly and open-minded / withhold judgement until you learn more?

But don't answer that question, it was rhetorical and I won't see you answer anyways because I have you on "ignore"

 

A burger joint in Greenville?
https://ltoburgerbargvl.com/

 

LTO - 12V/24V Automotive Starter battery | SCiB™ Rechargeable battery | Toshiba

 

So.....what exactly makes YOU such an expert ?
Hint: Nothing.