Bought Battery, It Sat on Shelf 17 Months, Installed Today: Readings are 11.4 / 11.1 / 14.3 V

Jan 2024, my toddler and wife were goofing around in the 2008 Prius. They ran the 12V battery (installed 7/2020) down to nothing.

Recharged it with trickle charger. Worked great since then.

Bought a new Interstate S46B24R AGM battery from Costco produced 2/2024. Old battery was working fine, and honestly, toddler parenting is exhausting, so kept putting it off. Replaced it today with the one I bought in 2/2024.

Did the readings in the diagnostic menu, which were.
One-brake tap: 11.4 V
Two-brake taps: 11.1 V
Engine on: 14.3 V

I understand now I shouldn't have done that, but what do you all reckon is the way forward?

Per ChatGPT and other forum posts, I ought to do an AGM smart charge to fully charge it overnight, then do the diagnostic check and hope it gets back up closer to 12.9 / 12.6 volts?

If so, any recommendations for a good smart charger for Gen 2 Prius? (never bought one before)
Also, when charging, should I have the charger "bite" the metal plate thing under the hood by the fuse box, or can I connect positive terminal directly to the 12V itself?

Any other advice / tips?

Thanks everyone

-Praise Dale

 

After talking to Costco people, I'm just gonna give the battery back to them, get 50% money back and get a brand new one. Then I don't have to buy a charger and always be having the "I hope the car starts" feeling with this 18-month old battery, plus it gets cold here in the winter