Replacing Mazda5 car battery
 

New member here. Got some questions regarding replacing my 2006 Mazda5 car battery,
1. Is it safe to use this memory safer from amazon to connects to the car OBII port when swapping the battery? I can use the 8 AA cell battery box for the hook up. I don't have a spare 12v battery. https://cimg3.ibsrv.net/gimg/www.maz...896f00d1c8.jpg
OR
2. I have this DC power supply for radio control car. It is basically a transformer with a voltage adjust dail from 9 to 13.5 volts with 3 amps continous current. Can I connect this at 13.5 volts to the car battery positive and negative cables or connects to the above amazon memory safer to avoid losing ECU, windows and fob key data while swapping the battery?
https://cimg0.ibsrv.net/gimg/www.maz...08338d1814.jpg

Thank you for your help! Very much appreciated.