Okay iv been researching and i could find a exact answer im looking for, i have 91 johnson 88spl fixed the charging system and rpm, (Replaced the rectifier) and the battery is getting about 15V+, i have been seeing that i want a group 27 or 31 battery, the guy at the store is saying i want a Cranking battery not a deep cycle, but online i thought it said get deep cycle, so can i have some people opinions on this or who has an ungregulated charging system. thank you!