There's a Simple protection is to add a diode that is reversed to take voltage from the battery to activate the relay to connect back the power supply to the battery, if its reversed the relay will save the day but it has to be a beefy relay that withstand more than 100A as in your case. A modified 12V 1500W gaming PC power supply can do the trick as well, I've seen one that is 120A capable. Thanks for your informative video.
