adjustable voltage, current limiting power supply is what you want
something like this.. https://www.amazon.com/Yescom-Precision-Variable-Digital-Adjustable/dp/B00SWK6M0M
set the voltage at 17 volts.. set the short circuit current at 1/3 of an amp.. hook it to you deeply or totally discharged battery and walk away for a few days.. the 17 volts at a current limited 1/3 of an amp may Dissolve the sulfate crystals.. i have pulled batteries back from totally dead after being slowly discharged over a month..
marine batteries at least at AZ are less expensive than others.. https://www.autozone.com/miscellaneous-non-automotive/marine-battery?filterByKeyWord=marine+battery&fromString=search&isIgnoreVehicle=false