Give 'em time! The manufacturers...
Pretty soon they're gonna pour H2SO4 4.0 Baumé into a group 24 and swear up and down it has 1,000 CCA, 300-amp hours (and in small letters print a 6-month warranty).
4.0 Baumé sulfuric acid is similar to SAE-20W in appearance but is 4-times as heavy as water.
Heat the battery carefully to 50c and check the "resting" voltage. The hissing sound is the dissolved plates precipitating down to the sediment chambers.
But oh man! The "resting" voltage will be in the stratosphere.
This is pure outright chicanery. My opinion of Full River has just fallen a few notches.
Compare it to Lyle Alzado (quote from Wikipedia)
"Lyle Martin Alzado (April 3, 1949 – May 14, 1992) was a professional American football defensive end of the National Football League famous for his intense and intimidating style of play"
All it took was huge batches of ANABOLIC STEROIDS to turn him into an animal. Uh Oh, mustn't cheat! Batteries are like humans. Cheat and you get fabulous factoids and brain cancer. There ain't no shortcuts without penalties!