The very best marine
batteries are the AGM
batteries by "Lifeline"
...we had to replace our bank of batteries in our previous s/v 8 years ago..and I think they are still working by all reports...they were pricey...but when they were initially delivered...one was slightly bulgy ..so they "Lifeline" sent us another one...and told us to keep the suspicious looking one, no questions asked. The point of this post is that the suspicious looking and slightly bulgy battery
went to work on our ranch and is still being used on the ranch...sitting out in the weather
used to run our submersible water
pump...this same battery
is still working fine w/no special care provided...so gotta say, when it comes to batteries...price vs. serviceability and convenience.. they are all expensive and heavy to lug around so IMHO its better to buy what is gonna last awhile.