Dolphin changed the chargers over the years that SM's were built. We added FullRiver AGM's 105 amp GRP 31 size to BeBe #387. I spoke with Reya, who makes Dolphin, and gave them model and serial numbers...they said no problem. I spoke to Leece-Neville who told me that to get the best life out of the AGM's I should remove the built-in regulator and add a smart regulator to the 175 Amp alternator. I bought the smart regulator, but never added it. It cost about $400 with temp leads to the batteries and to the alternator. I will sell it at a discount if someone wants it. We got 4 years out of the FullRiver batteries when 2 of them became weak. We replaced the entire set in Greece with Varta Freedom batteries.